Problems of Humid Tropical Regions Problèmes des régions...

Problems ofHumid Tropical Regions

Problèmes desrégions tropicales humides

U N E S C O

Humid Tropics Research

Recherches sur la zone tropicale humide

In this series / Dans cette série :

Study of Tropical Vegetation. Proceedings of the Kandy Symposium / Méthodes d'étude de la végétation tropicale. Actes ducolloque de Kandy.

Problems of Humid Tropical Regions ¡ Problèmes des régions tropicales humides.

Published in 1958 by the United NationsEducational, Scientific and Cultural Organization

19 Avenue Kleber, Paris-16e

Printed by Firmin-Didot et C'', Paris (France)

Publié en 1958 par VOrganisation des Nations Unies pour Véducation,la science et la culture, 19, avenue Kleber, Paris-16e

Imprimé par Firmin-Didot et C'e, Paris (France).

(J5l Unesco 1958Printed in FranceNS. 56. VI. 2 A.

Foreword

THE General Conference of Unesco at its eighth sessionauthorized the Director-General to promote the co-ordination of research on scientific problems relating

inter alia to the humid tropical zone and to promoteinternational or regional measures to expand such research.

The first step taken by Unesco was to collect informa-tion about problems of the humid tropical regions in itsMember States, for presentation to a preparatory meetingof specialists in humid tropics research which was invitedto recommend subsequent measures.

Three general reports reviewing the problems of threehumid tropical regions (the Amazon, the Caribbean andthe South Asian regions) were commissioned. The authorsof these reports were asked not only to indicate the problemsof the regions, but also to review current basic researchbeing carried on of relevance to these problems and tosuggest lines along which further research might becarried out. The reports, which were to be based on avail-able published literature, were intended also to draw

attention to those principles and methods emerging fromthe work done in the region which might be of interestto other humid regions.

Three special reports were commissioned in additionto the three general reports in order to illustrate specialaspects of some of the many problems of the humid tropicalregions. These concerned: biological problems in theBelgian Congo; entomological problems in South Asia,and problems related to the Development of water resourcesin the Philippines.

It is obvious that there are other special problems similarto the three mentioned above which call for special treat-ment and it is intended that other regional and topicalreports be prepared and published.

These six reports are presented here together. In publish-ing this volume, Unesco hopes that it will serve to drawattention to the various problems of the humid tropicalregions and to stimulate research for the solution of thoseproblems.

Avant-propos

LA Conférence générale de V Unesco a, au cours de sahuitième session, autorisé le Directeur général àstimuler la coordination des recherches sur les pro-

blèmes scientifiques intéressant la zone tropicale humideet à favoriser Vadoption de mesures de caractère inter-national ou régional visant au développement de cesrecherches.

L'Unesco s'est efforcée tout d'abord de recueillir desinformations sur les problèmes des régions tropicaleshumides existant dans les États membres. Ces communi-cations ont été présentées à une réunion préparatoire despécialistes des recherches sur la zone tropicale humide,qui a été invitée à recommander les mesures à prendreultérieurement.

Trois rapports généraux distincts, analysant les pro-blèmes de trois régions tropicales humides (la régionamazonienne, la région des Caraïbes et les régions humidesde l'Asie du Sud) ont été demandés à des spécialistes.Les auteurs de ces rapports devaient non seulement pré-ciser les problèmes de ces régions, mais également dresserun compte rendu des recherches fondamentales en cours

sur ces problèmes à entreprendre. Ces rapports devaients'inspirer des ouvrages publiés sur la question et attirerl'attention sur les principes et les méthodes se dégageant del'œuvre déjà accomplie dans la région en question, et dontpourraient bénéficier les autres régions tropicales humides.

Trois rapports spéciaux ont également été demandés.Ils mettent en évidence certains aspects de quelques-unsdes problèmes des régions tropicales humides, et en parti-culier : les problèmes de biologie au Congo belge; lesproblèmes d'entomologie en Asie méridionale; les pro-blèmes du développement des ressources hydrauliques auxPhilippines.

Il existe évidemment d'autres problèmes particuliersde même nature et qui demanderaient également à êtretraités à part. A cet effet, la rédaction d'autres rapportsrégionaux et locaux est envisagée.

Ces six rapports ont été réunis dans le présent ouvrage.En le publiant V Unesco espère attirer l'attention sur lesproblèmes scientifiques des régions tropicales humides etencourager les recherches en vue de la solution de cesproblèmes.

Contents/Table des matières

I. General Reports I Rapports généraux

Report on the Amazon region, by Dr. Felisberto C. Camargo 11Rapport sur la région amazonienne, resume 23

Report on the Caribbean region, by Dr. Enrique Beltran 25Rapport sur la région des Caraïbes, résumé 35

Report on the humid regions of South Asia, by Dr. E. K. Janaki Ammal 43

Rapport sur les régions humides du sud de l'Asie, résumé 52

II. Special Reports /Rapports spéciaux

Rapport sur les problèmes biologiques de l'Afrique tropicale humide, par G. Marlier 57Report on biological problems in the humid tropical zone of Africa, résumé 62A report reviewing entomological problems in the humid tropical regions of South Asia, by Dr. A. P . Kapur . 63Rapport sur les problèmes entomologiques des régions tropicales humides de l'Asie du Sud, r é s u m é . . . 76

Problems of the humid tropical Philippines with special reference to water resources development, by Hon.Filemon C. Rodriguez 86

Les problèmes des Philippines tropicales humides, notamment en matière de mise en valeur des ressourceshydrauliques, résumé 98

Subject index/Index des matières 101

General ReportsRapports généraux

Report on the Amazon Regionby

Dr. Felisberto C. Camargo,Director, Serviço Nacional de Pesquisas Agronómicas,

Rio de Janeiro

According to Herman Wagner, the regions with a hothumid climate throughout the world have a total areaof 29,700,000 square kilometres, or 36.1 per cent ofthe total land surface.

Of this the Amazon region accounts for roughly5 million square kilometres, or one-sixth of the whole,of which 4,161,482 are in Brazil.

Other areas of humid tropical climate in the Americasare north and east of the Amazon region, in CentralAmerica and the West Indies, and east and southalong the Brazilian littoral between Pernambuco andRio de Janeiro; however, the Amazon region is stillthe largest single geographical unit of its kind, notonly in America but in the world, and contains thecontinent's largest reserve of land and water resourcesfor development by man.

The 4 million odd square kilometres of the regionlying in Brazil are served by the finest and most exten-sive fluvial system in the world, with rivers extendingfan-wise up country from the Atlantic coast. For shipsup to 10,000 metric tons navigation is unrestrictedanywhere between Amazonas and Solimôes, and theycan even penetrate as far as Iquitos 3,796 kilometresfrom the river mouth.

Between the jungle fringe along the banks of theAmazon and the "high ground" are flood plains regu-larly inundated, and lakes which expand vastly tocover thousands of square kilometres, when the riveris in spate. The lakes provide excellent conditions forthe breeding of fish of the Tilapia genus which feedon algae and water weeds, and annual yields of abouthalf a million tons of human food could be securedfrom them.

To a greater or lesser extent examples of all knowngeological formations, from the most ancient to the

most recent, are to be found in the Amazon territoryof Brazil.

The rule-of-thumb classification of the land in theterritory is into "flood plain", or land subject to inun-dation, and "high ground" out of reach of the seasonalspates.

As a general rule, land in the humid tropics notperiodically flooded is extremely poor in fertilizingelements, save for that on the flanks, or in the vicinityof, volcanoes where soil fertility is maintained by theash and other material expelled from the crater. Thereis not a single volcano in the Amazon territory andthe fertility of the "high ground" is therefore low.An additional adverse factor is that much of it, thepart immediately above the flood plain, is a Tertiarysilt formation laid down during the period when theAmazon region was a vast lake formed by the upheavalof the Andes.

As is the case everywhere else in the humid tropics,the sedimentary soils of the "high ground" in theAmazon region are unsuitable for intensive annualcropping; their fertility rapidly becomes exhaustedand its restoration is costly.

Another circumstance common to the Amazon"high ground" and other tropical regions in the worldis the vicious practice of "shifting agriculture", whichplays havoc with forest resources and is a main factorin the debasement of human living standards.

In 1948 manioc and rice cultivated on these linesaccounted respectively for 38,983 and for 20,951 hectaresof the total of 104,307 hectares under cultivation inthe State of Pará.

In the district served by the Bragança Railway,manioc growing is wreaking appalling destructionamong the finest timber resources of Pará State.

The Instituto Agronomico do Norte, a Ministry ofAgriculture agency in Belém, Pará State, sought toremedy the situation by beginning the experimentalcultivation of timbo (Derris urucu), primarily for therestoration of the soil; but the appearance on the

Problems of humid tropical regions/Problèmes des régions tropicales humides

FOREST AGRICULTURE ANNUAL CROP"VÁRZEA* AGRICULTURE

HABITATION ZONE

DAIRY AND SMALL ANIMALS

HOME CONSUMPTION

XBRAGANÇA „jíft

EXPORT PRODUCTS PARÁ STONE

OL.D QUATERNARY

TERTIARY BCD

WATER TRANSPORTATIONTO BELEM

GUAMA RI VCR

FIG. 1. A section across Guama River, its flood plain and adjoining high ground.

market of synthetic insecticides reduced the price oftimbo root to such a level that the policy could notbe made effective. Nevertheless the cultivation ofDerris urucu is a first-class means of soil restoration,as the enormous masses of foliage it produces providecomplete protection for the soil surface.

There are a few small areas of "high ground" in theAmazon territory where the soil has been formed bythe decomposition of diabase outcrops. On thesepatches, where disintegrating blocks of diabase arestill to be found on the surface, fertility is greater.

As far as the expansion of intensive annual crops isconcerned, the correct practice for the Amazon terri-tory is that of the Far East, and the very first step ofall should be to use the flood plains to grow rice as astaple food to replace manioc flour.

BRINGING THE FLOOD PLAIN INTO

CULTIVATION

Intensive annual food crops need to be transferred fromthe "high ground" to the flood plains. For develop-ment purposes, the .latter fall into two categories, namely:1. Amazon estuary group: flood plains subject to tidal,

and not seasonal fluvial, inundation—i.e. thoselying between the mouth of the River Xingu andthe open Atlantic.

2. Flood plains of the interior: flood plains above themouth of the River Xingu, where inundation iscaused by the seasonal spates, and tidal influencesare nil or insignificant.

FLOOD PLAINS OF THE AMAZON ESTUARY

The following plan for developing the flood plainsaround Belém, Pará State, was put forward by the

writer at the Denver (Colorado) Inter-American Con-ference on the Conservation of Renewable NaturalResources in 1948 1 and at the United Nations Scien-tific Conference on the Conservation and Utilizationof Resources held at Lake Success, New York, between17 August and 6 September 1949.

The plan calls for the classification of the land alongthe River Guama, Pará State, and along the Amazonestuary into two separate categories—the flood plain,now covered with açai and ucuuba, which should bedrained and used exclusively for annual food crops,and the high ground to be reserved for tree cropsproviding permanent shade for the soil.

As things now are, these flood plains remain unused,but to bring them into cultivation is an extremelyeasy matter. As inundation is caused exclusively bythe action of the tides and not by the height of theriver, the problem of rendering the land cultivable canbe solved simply by cutting drains to shift the tidalwater. Judging by the pilot scheme carried out by theInstituto Agronomico do Norte on land of its own,bordering the River Guama, all that is needed is tocut drains with a bottom width of 2 metres throughthe river bank at 200 metre intervals, and the floodplain will be cultivable.

The slope of the high ground along the line of itsjunction with the flood plain should be reserved forthe farmhouse, pens for small livestock and a byre fordairy cattle, as shown in Fig. 1.

The siting of the Escola de Agronomia da Amazonia,founded by the writer and located on land belongingto the Instituto Agronomico do Norte in Belém, ParáState, conforms to these principles. The main building

1. The paper was published by the Bulletin of l/ie Museu Goeldi, 1948,Vol. X, pages 123-147, Belém, Pará State, Brazil.

Report on the Amazon region

has been erected at the edge of the high ground, facingover the flood plain and the area set aside for experi-ments in the mechanized cultivation of annual crops.Behind and on either flank of the main building arethe livestock sections and plantations of trees.

The point of siting the school's principal buildingthus was to drive home to its students, daily and hourly,throughout the whole period of their studies, the newprinciples of rational land utilization as they applyin that part of the Amazon territory between themouth of the River Xingu and the Atlantic.

Suitable drainage, on the flood plains bordering theGuama River, has enabled the Instituto Agronomicodo Norte, without the use of fertilizer, to harvestbetween 3,000 and 3,500 kilograms of rice per hectareduring the rainy season, and the installation there ofirrigation machinery in addition will make it possibleto secure two rice harvests, or a rice harvest and aharvest of another crop, each year.

The scheme thus put forward a practical answer tothe problem of developing the lands of the Amazonestuary; and Dr. Alvaro Adolfo da Silveira, the FederalSenator for Pará State, introduced a Bill into theNational Congress for a settlement on the River Guamabased on land utilization along the lines advocatedby the writer.

Unfortunately the project has not so far been carriedthrough, as the technical staff responsible for landsettlement in Brazil has not yet grasped the principlesapplicable to humid tropics schemes, and the choiceof personnel to carry out the foundation of the newcolony was likewise unhappy.

All attempts at colonization so far made in theAmazon territory have come to nothing, throughfailure to inculcate agricultural techniques adapted tohumid tropical conditions.

However, it is hoped that, as qualified agriculturalengineers emerge from the Escola de Agronomia daAmazonia, set up under the scheme for the planneddevelopment of the tropical areas with a humid climate,the ideas developed in the Instituto Agronomico daAmazonia will spread to the other technical agenciesof the region.

In any case, public opinion is already converted tothe notion of opening up the flood plain, in view ofthe fact that the returns are immediate.

INLAND FLOOD PLAINS

The inundation of the up-country flood plains alongthe Amazon above the mouth of the River Xingu iscaused by the great spates of the rainy season, and theland is under water between five and seven monthsof the year. Thus the scheme adopted for the recla-mation of the land subject to tidal flooding is notapplicable to flood plains of the inland type, which areno more than vast lakes for the greater part of the year.

At Santarém, Pará State, the depth of water in the

river at its highest is between 6.04 and 7.39 metresand the minimum, in the low water periods, from under1 metre to 3 metres.

On the Lower Amazon, the annual spates cover theflood plain to a depth of between 4 and 6 metres fromFebruary to September; at the peak of the floods theareas of Lake Maicuru and Lake Villa Franca increaseto over 1,000 square kilometres each, and scores ofkilometres of land along either bank of the river areunder water. Thus jute growing around Santarém isat the moment confined exclusively to a few of thehigher areas along the wooded banks of the river.

At Manaus, as can be seen from the gauge readingsfor the period 1931-1952 below, there is a difference of8 to 10 metres between the flood and low water levels.

TABLE 1. Water gauge readings at Manaus and Santarém atthe periods of peak flood and extreme low water

1931193219331934193519361937193819391940194119421943194419451946194719481949195019511952

26.6027.7028.1027.6027.6026.6026.9027.9028.0026.7027.0027.6028.1028.8027.0027.9026.7027.5028.3028.2028.4027.50

Manaus

Low water

17.5018.8016.4021.1016.1014.9016.1017.9020.5019.5016.2017.3016.8018.1016.7017.6019.5015.6020.0015.7018.0517.14

6.186.366.356.736.895.945.976.406.646.046.246.346.727.026.576.826.106.867.327.396.827.08

Santarém

Low water

1.141.341.032.581.140.741.161.582.952.431.341.421.441.851.381.612.241.102.681.141.941.55

Being affected by flooding on such a scale, the floodplains, lakes and islands of the inland Amazon territoryare to all intents and purposes unexploited agricul-turally while serving no other substantial purpose,with the exception of Careiro Island which is beingfarmed extremely profitably to supply the city ofManaus, and those patches a little above the generallevel which are used for "shifting" jute cultivation,with farmers and workmen living in straw huts of alife of two years.

To bring the Lower Amazon flood plains into culti-vation, the writer is pursuing a scheme of soil buildingby siltation channels, and breeding stock—in this case

ri•I£o

Indian water buffaloes—on them, as a first step towardsmaking them productive.

With no existing advantages to be sacrificed in thecase of land serving practically no purpose, soil buildingon the low-lying flood plain can be brought about bythe simple process of diverting the silt-laden floodwaters of the River Amazon towards the riverside lakes.

To effect this, canals 5-8 metres deep are beingplanned and cut to connect the Amazon channel withLake Maicuru in Pará State. Thus when the river startsto rise, the water passes through the canals across thebanks, and flows towards the lake, leaving a layer ofsilt which advances further each year into the lake bed.

By this process of induced natural land building,the very first deposits of silt even up the surface of theflood plain and consolidate the marshy stretches, mak-ing it easily feasible to breed water buffalo on the landfrom the earliest stages; the animals spend most oftheir time in the water browsing on the water vegeta-tion, and sleep on the banks of the siltation canals.

It should here be pointed out that the Amazon dailytransports towards the Atlantic 3 million metric tonsof sediment and 50,000 tons of potassium chlorate.

Thus, despite the wealth it represents, it is also anagent of destruction, playing havoc with the soils ofa basin more than 5 million square kilometres in extent

The object of constructing siltation canals is to forcethe Amazon to deposit part of its load of eroded soiland fertilizing elements midway on its path to the seato create "made" land of high fertility by consolidatingthe surface of the bank side lakes' flood plains andraising their level.

There are, of course, a number of natural channelsin the banks of the Amazon connecting it with thelateral lakes and "hollows", and this circumstancehas been a potent factor in the formation of the presentflood plains.

There is even a channel connecting the River Orinocowith the Rio Negro, 365 kilometres in length with adrop of 21 metres, where the Orinoco has broken outinto the Amazon basin through formations of graniticorigin; though even if this had not occurred, the twobasins would by now have been connected to affordpassage for vessels of large tonnage between Venezuelaand Brazil.

From his studies of the effects produced by naturalescape channels all over the Lower Amazon region,the writer arrived at a plan for the reclamation of theflood plains; and towards its execution, he secured theexpropriation, by the Federal Government, of theformer Cacaual Grande fazenda as an experimentalstation for "land building" operations, after attemptsto purchase the property on a friendly basis had failed.

On the fazenda being paid for and handed over atthe end of 1949, an immediate start was made with thesurveying and plotting of the proposed canal system;but before this preliminary stage was completed thegreat flood of 1950 forced us to speed up the work and

to cut an initial canal at once, near the former estatehouse of the property.

The work was done by a gang of 50 men, accommo-dated in two hulks converted into floating hostels andmoored off the canal intake.

Between mid-April and mid-May water spread overthe whole property, which became to all intents andpurposes part of Lake Maicuru. The hand-dug canalprovided the first artificial inlet to the lake from theAmazon, which, from its normal width of 7 kilometresat that point, attained a width of 70 kilometres.

With the falling of the waters in September-October1950, the first "silt layer" emerged; it was over 1 kilo-metre in length, from 5 to 40 centimetres in thickness,and covered an area of 16 hectares in the Lake Maicurubasin. It was photographed in October 1950 byDr. Renato Gomes de Farias, the then Director of theNational Department of Animal Husbandry, who wasvisiting the water buffalo herds of the Lower AmazonExperimental Station.

The reopening of a former natural channel, thePiapo, had also been undertaken in 1950, but theexperiment showed that it is much cheaper to make anew canal than to clear an old channel blocked withheavy timber.

On the writer's instructions, Dr. Harald Sioli, then atechnical officer of the Instituto Agronomico do Norte,carried out a hydrological survey of the canal. Hisobservations showed that on 11 May 1950 the dischargeof water into Lake Maicuru was 18 cubic metres persecond. He also found, after drying out samples at110°C, that the amount of solids in suspension was0.1284 grams per litre with a calcined content of0.1158 grams per litre. His findings are shown in detailin Boletim técnico No. 24 of the Instituto Agronomicodo Norte.

In 1950 the first mechanical excavator was imported,and in 1951 a visit by a reporter from a well-knownAmerican magazine served as the occasion for theformal opening of the canal dug by hand the previousyear and reçut mechanically afterwards.

In view of the success of these initial operations,funds and official permission were secured for theimportation of a further six excavators with full equip-ment, which made it possible to increase the work tempoand make a start on the cutting of other canals.

The first to be dug is 30 metres across and 6 metresin depth during the flood season, and its rate of flowis 2 metres per second. Its normal discharge duringthe months of April, May, June and July is over 200 cubicmetres per second, or double that of the Rio Paraibado Sul, in Rio de Janeiro State, and other rivers famousthroughout the world.

This first canal was the only one completed in 1953and it was christened the Senador Novais Filho Canalas a tribute to a Minister of Agriculture who, in hisbrief tenure of office, withheld nothing required toexpedite the work.

Problems of humid tropical regions /Problèmes des régions tropicales humides

Later, five further canals—the Maroja Neto, Remanso,Fernando Costa, Vicente Chermont de Miranda, andDores—were opened. Three of them are named aftermen of mark, Dr. Fernando Costa having been theMinister of Agriculture who founded the InstitutoAgronomico do Norte, Dr. Maroja Neto (as servingGovernor of Pará at the relevant time) having had adecisive voice in the acquisition by the Brazilian Govern-ment of the plant of the former Companhia FordIndustrial do Brasil S.A., and the Amazon territoryowing the introduction of the buffalo on Marajó Islandto Dr. Vicente Chermont de Miranda.

A graph is given on this page (Fig. 3) of the dischargeof the Novais Filho Canal over the period January-September 1954, the maximum discharge observedhaving been in the first fortnight of June. The dischargefigures for all the canals on 1 June 1954 were as follows:Maroja Neto, 152.4 cubic metres per second; NovaisFilho, 274.9; Remanso, 75.6; Fernando Costa, 94.9;Vicente Chermont de Miranda, 38.2; Dores, 34.2;total: 670.2.

It will be noted that the discharge of the NovaisFilho Canal was 274.9 cubic metres per second and thatthe total for all six (including the most recent, theDores Canal) was 670.2 cubic metres, which representsthe transference of an amazing bulk of silt-formingmaterial to the flood plain, since the water goingthrough the canals contains a minimum of 100 gramsof sediment per cubic metre. Thus, with a dischargeof 670 cubic metres per second, the following quantitiesof suspended solids are delivered: 67 kilograms per

second, 4,020 kilograms per minute, 241 metric tonsper hour, or 5,784 metric tons per day.

In a few years' time, detailed evidence will be observ-able of the merits of an undertaking started in theface of every kind of protest, but even today whole-heartedly supported by the neighbours of the LowerAmazon Experimental Station who formerly opposedit tooth and nail.

The ultimate object of the siltation operations onthe Lower Amazon is to create cultivable areas, bya "polder" system adapted to humid tropical condi-tions. It should here be made clear that the proceduredescribed cannot be used for inhabited flood plainswhere assets have been created on a major scale; itis however the ideal system for the whole interior ofthe Amazon territory above the mouth of the RiverXingu, where the only works of man to be found lackeven the smallest value.

The Lower Amazon Experimental Station's siltationcanals will also serve to shorten communications withthe interior of Lake Maicuru, raising land values andbroadening the horizons of the backward inhabitantsof the region. The Novais Filho Canal is easily navigablein the rainy season by vessels of up to 100 tons. Forthe future, the writer is planning the cutting of a canalto connect the Tapara inlet, below the Fazenda San-tana, with the interior of Lake Maicuru, with a viewto causing the formation of a new arm of the Amazonfor the siltation of the lake, and to restoring the pri-meval through route which formerly existed on theedge of the high ground on the left bank of the Amazon

Cubicmetresper second

PIG. 3. Novais Filho Silting Canal (Discharge in 1954).

Dm'. /

5^ ^ ^ 6 4

^ » ^ 2 3 5

!. 2, \

k \1,67

U T V ; 3 0

Velocityin metres

per second3m

Jan. Fév. Mar. Jun. Jul. Aug.Apr. May _ _ .

Discharge of canal in cubic metres per secondVelocity of water in metres per second.

Sep. Oct.

Report on lhe Amazon region

by connecting Monte Alegre directly with Alenquer.A width of 50 metres will be needed, to make thistrunk canal navigable by vessels of 1,000 tons.

To conclude this section of the present paper, therefollows an estimate of the areas of flood plain in theAmazon territory, classified in five groups.

TABLE 2. Estimate of the area of the Amazon flood plains1

Area insquare kilomètres

Group A — Forest flood plains of the Ama-zon estuary 10 000

Group B — Open flood plains of the Ama-zon estuary (Arari) 10 000

Group C — Lower Amazon flood plain fromthe confluence of the Xingu to Óbidos:1. Iquiqui or "Boi Bumba" between the

rivers Xingu and Amazon, Almerim andMonte Alegre 4 000

2. Maicuru and Ituqui 1 3003. Flood plains of the Tapara Islands, adja-

cent areas and Alenquer 8004. Flood plains of Vila Franca 1 000

Group D — Flood plains of the Middle Ama-zon; flood plains between Óbidos andconfluence of the River Madeira:1. Faro, Oriximiná and Itaquatiara 2 2002. Flood plains of the Madeira and Parin-

tins 8 500

20 000

10 700

Group E — Flood plains of the Solimões;flood plains from the confluence of theMadeira to Tabatinga1. Flood plains on the left bank of the

Madeira and the right bank of the Ama-zon, flood plains of the Autaz-Mirim,Autaz-Açu and Madeirinha rivers and ofthe Careiro Islands region 1 400

2. Flood plains of the Manacapurú, Rightbank of the Solimões from Manaus to thePurus and the islands in this sector 1 400

3. Flood plains between the mouths of thePurus and Coary Rivers. Flood plains ofthe Badajos and Piorini 6 800

4. Flood plains between the mouth of theCoary and Juruá Rivers 9 000

5. Flood plains between the mouth of theJuruá and Tabatinga. Flood plains of theJapurá above the "Paraná Aranapú" 8 000

GRAND TOTAL26 60064 400

The above table was compiled for a paper, "Reclama-tion of the Flood Plains of the Amazon Territory",

prepared by the present writer for the Pan-Americanmeeting on the Conservation of Natural Resourcesheld in 1953.

DEMOGRAPHIC DENSITY

According to the 1950 census the Brazilian part ofthe Amazonian forest region, covering 4 million squarekilometres, has a population of barely 2,751,436;distribution by States is as follows: Acre, 114,755;Amapá, 37,477; Amazonas, 514,099; Goiaz, 52,608;Guaporé, 37,935; Maranhão, 741,028; Mato Groso,113,145; Pará, 1,123,273; Rio Branco, 18,116; total,2,751,436.

The population density is thus not merely low butuneven. Average density is one person per 2 squarekilometres, against the 1,000 per square kilometre ofsome areas in Java.

Outside of the State capitals, the greatest density isin the area served by the Bragança Railway, ParáState, where it ranges between 10 and 50 per squarekilometre.

Of the total population of the Amazon territory,one-sixth lives in the two State capitals of Belém andManaus, one-third practises the system of "shifting"agriculture, and half are employed in the forest extrac-tion industries.

The first forward step which has been taken in theagricultural sphere is in stock raising. The establish-ment in Fordlandia, under the Instituto Agronomicodo Norte, of a breeding herd of the Nellore strain, nownumbering over 1,300 head, is the main stepping stonetowards the development of intensive beef cattle pro-duction throughout the Brazilian Amazon territory andthe neighbouring areas.

A prime example of sound development policy forthe humid tropics is the building up, at the LowerAmazon Experimental Station of the Instituto Agrono-mico do Norte, of a herd of over 1,000 buffalo—theideal meat and milk producer for these climatic condi-tions, more particularly in South America.

Given the present circumstances of the Amazonterritory, the great need is immigration from otherareas, to increase food production; the 50 per centof the population represented by the tied labour ofthe forest extraction industries will be irrecoverableand the more rational redeployment of the manpowerin shifting agriculture will be extremely difficult, thesnag, in either case, being the powerful regional poli-tical forces not yet ready to accept desirable agrarianreforms.

This makes it necessary to promote immigration and,of the available reservoirs of human population capableof adaptation to Amazonian traditions, it seems to thewriter that Puerto Rico, in particular, could make asizeable contribution.

1. Based on the maps compiled by the Aeronautical Chart Service, Washing-ton (preliminary base), series 1:500,000.

B R A N C O

M A Z O N A S

a u A p o R e

G R O S S O

FIG. 4. Demographic density contours of Amazon forest region (1950 census).

CLIMATE

Lying as it does along the Equator and without highinternal land masses, the Amazon territory has afairly uniform humid climate.

There is a zone of less humid climate running northand south from the Valley of the Rio Trombetas tothe Tapajos-Xingú Basin where precipitations (seeSalomão Serebrenick's rainfall map No. 4) range be-tween 1,800 and 2,000 millimetres per year.

In his climatic map No. 7, Serebrenick also shows auniform region east of Manaus of more humid climate,which he designates TiU (tropico iso-super-umido),having unfortunately rejected the Koeppen systemof classification for one of his own devising.

However, for the Amazon region, the thoroughgoing

adoption of the Koeppen system will be preferable,with modifications in conformity with its basic prin-ciples to designate any new climatic types which maylater become identifiable, as fuller meteorological dataare accumulated.

Serebrenick's so-called "TiU climate" is extremelyinteresting, with similarities to the climate of the Medanregion in northern and eastern Sumatra. On the Koeppensystem it could be represented by the symbols Af, toindicate precipitations of not less than 100 millimetresin the driest month. It could therefore be designatedan "Af climate", restricting "Af climate" to theforest zones with precipitations of between 60 and99 millimetres in the driest months.

In the Amazon territory, climate Af occurs in anarea west of the mouth of the Purus River; the homo-

climatic Medan area in Sumatra is where the greatrubber plantations have established themselves.

The climate in various parts of the Brazilian Amazonterritory is analysed on the Koeppen system in a workby Professor José Carlos Junqueira Schmidt, publishedin Brazil under the title 0 clima da Amazonia; and onpages 16 and 17 he gives climatic tables for São Gabriel,the River Negro and Belém, Pará State, to which heassigns the common designation of An.

However, the figures for the months of October andNovember show that in Belém precipitations do notreach 100 millimetres, whereas in São Gabriel, in thedriest month (October), they are over 150 millimetres.Thus there is a new "Koeppen system" climatic typecorresponding to Salomão Serebrenick's TiU climate.

Having regard to the excellence of the Koeppensystem, the writer associates himself with the recom-mendations of Jorge A. Vivó, in his "foreword" tothe translation of Wilhelm Koeppen's work preparedby Pedro R. H. Pérez, 1948, that the Koeppen systembe adopted exclusively: any new local system willnever achieve world-wide currency, and will only serveto render comparison of the climates of the differentparts of the world more difficult.

THE " E X T R A C T I V I S T " MENTALITY

The wild rubber which originally made the BrazilianAmazon territory a positive Klondike, has made theextraction industries an obsession with almost all thoseresponsible for guiding the economic life of the region,despite the depression conditions from which the areahas been suffering ever since the cultivated rubber ofthe Far East became dominant in world markets.

The will o' the wisp of wealth from the forest is amuch more serious plague in the Amazon territorythan yellow fever, sleeping sickness, malaria or otherscourges to be found in humid tropical regions through-out the world.

This "extraction" mentality, is the ruin of the regionand the principal cause of its economic backwardness,for, ever since the golden age of rubber extraction, theproduction of food crops has been abandoned. Today,therefore, the Amazon territory, with everythingnecessary to grow abundant food, is still importingmilk, rice, beans, meat, fats, etc., from abroad or fromother Brazilian states.

The local leaders, instead of allowing the wild rubberindustry to die a natural death, pursue a policy ofartificial price support; and the vicious circle continues,with continuously rising production costs and cost ofliving, and an increasing shortage of labour for, andlack of interest in, the alternative policy of rationalcropping.

It is true that the sedimentary soils of the "highground" in the Amazon territory are poor farmingland; but the flood plains offer splendid land of highfertility. However, man, obsessed with the "extraction"

outlook, continues to turn his eyes towards the forestrubber of the upper rivers so that, around Belém itself,there are still about a million hectares of flood plainin a practically virgin state, the output of which couldgive the territory a balanced economy.

A particularly striking example of the ruinous"extraction" mentality is the ucuuba harvesting; itis well worth examination.

The ucuuba (Virola surinamensis), a species akin tothe nutmeg of the Far East, is an excellent source offat and is a typical denizen of the estuary flood plainperiodically inundated by the tides.

The fruits ripen at the time of the great equinoctialspring tides, which cover the flood plains daily at highwater, with fallen pods floating on the surface. As thetide falls again, quantities of the floating pods aredrawn into the rivulets which form in the under-growth.

The local inhabitant then paddles his canoe wherethe outward flow of water is greatest, and all the workhe has to do is to fish for the floating pods as theycome bobbing along like strings of beads out of theforest on the outgoing tide. At low water, after twohours' work, the collector goes home; and the nextday, when the tide changes, he lets the current itselfcarry him to the strategic point and fishes for podsagain.

These original harvesting methods ought to be usedas a model for handling commercial crops of ucuubaon' this type of flood plain to exploit the tides forcollecting and shifting the crop. It is a necessary anda promising experiment, and has already been suggestedby the writer in the Amazon Territory, however, ascarrying it out involved the labour of planting theucuuba, it was not accepted. The "extraction minded"attitude was: "If the stuff grows wild, why plant i t?"

Happily, some new ways to easy wealth are emerg-ing in the Amazon territory—exploitation of themanganese deposits in the Amapa—and the attractiveprospects implicit in the success of the first oil wellsunk in Nova Olinda.

With the discovery of oil in commercial quantities,there will be opportunities for making fortunes in theAmazon territory and then it is to be hoped that theenergies of the extraction industries, drawn into thisnew rush for easy wealth, will let sound agriculturesurvive.

In the writer's view, discovery of oil and othermineral wealth in the Amazon territory will be theonly remedy for the plundering of the soil and forests.

AGRICULTURAL RESEARCH BODIES IN THEAMAZON TERRITORY

Museu Goeldi

The Museu Goeldi was founded by the State Govern-ment of Pará in the golden age of wild rubber produc-tion, and for some years had a full and brilliant record

of basic research in ecology, botany, icthyology, ethno-logy, entomology, etc.

With the economic crisis which followed the emer-gence of cultivated rubber in the Far East, directionwas lost and the Museu Goeldi, after starting andcarrying through a considerable amount of first-classresearch and publishing 11 annual reports, graduallybecame a mere zoological garden.

Instituto Agronomico do Norte

This institute, of which the director is Dr. FernandoCosta, was founded by the Ministry of Agriculture in1940 to carry out agricultural research in the Amazonterritory under Federal Government auspices.

The institute has a network of experimental stationsthroughout the region, and at its Belém headquartersin Pará State there are departments of chemistry,botany, selective plant breeding, and entomology, andsoils and rubber technology laboratories.

The Instituto Agronomico do Norte has built up themost comprehensive agricultural library in the country,which now holds complete files of over 300 scientificreviews, some of them founded moie than a century ago.

The institute's achievements include the restorationof the Ford plantations in Belterra, determination ofthe principles for flood-plain development in theAmazon estuary, initiation of the project for the silta-tion of the Lower Amazon flood-plains, the formationin Fordlandia of the largest Brahmin cattle herd ofthe Nellore strain in America and the introductionand systematization of the breeding of Indian waterbuffaloes in the Lower Amazon. It has also made thecountry completely self-sufficient in selected jutestrains and is now carrying out genetic research onBrazilian rubber varieties, cacao, oil palm, rice andother tropical species.

The Ford Plantations on the Tapajós

At the end of 1927, legislation was passed by theLegislative Assembly of Pará State, to permit theconcession of one million hectares of land, in the muni-cipalities of Itaituba and Aveiros, for the establish-ment of the Companhia Ford Industrial do Brasil,with head offices in Belém, Pará.

Financially, the new rubber plantations of Ford-landia were a failure. Socially, however, the company'soperations were of high significance, for they pavedthe way to the coming of a Mixed Experimental Stationfor agricultural research, a source of revitalizationwhich will yet be of crucial importance in the economyof the Amazon territories.

With all its technological deficiencies and its failuresto test its theories by experiment, the company didnot labour in vain, for it was the sheer mass of over amillion ungrafted rubber trees planted which yieldedthe first individuals resistant to "leaf disease" and usedfor the phenomenal grafting operation which savedthree million rubber trees in the Belterra plantations.

It was an ill-planned but not a wasted effort, for theAmazon territory has profited greatly from it.

When the Ford Company began rubber plantingin 1928, there was no fund of experience in the region,or anywhere in America, to furnish precepts and guid-ance for the execution of a really gigantic under-taking.

Planting on the Fordlandia and Belterra scale wasunwise simply because blank ignorance of the probablebehaviour of rubber trees in their native habitat, whenassembled in large concentrations, made operations ofsuch dimensions a pure gamble.

The first attempt in Fordlandia was an utter failure.However, the authorities refused to admit defeat, andin 1934 began the attempt to start a second group ofplantations on the Tapajós tableland—taking over thepresent Belterra area of about 250,000 hectares forthe purpose, on 4 May 1934, in exchange for part ofthe Fordlandia estate, which, after the failure to estab-lish a rubber plantation there, was little by littleabandoned in favour of concentration upon the newand apparently more favourable site.

The Belterra plantation, created by grafting high-yield scions imported from the East on to native stocks,ran into serious difficulties in the period 1941-1948.The Company decided to suspend its programme ofplanting new stands, endeavouring meanwhile to turnits bitter experience in Fordlandia to advantage byusing double grafts of the resistant strains evolvedthere to save the Belterra plantations, where all thegrafted rubber trees to the number of hundreds ofthousands, were being so heavily attacked by "leafdisease" as to be considered doomed. It was doublegrafting in the shape of complete crown grafts whichsaved them.

This was yet another gamble; it was a desperateattempt to save 2 million rubber trees, with the riskof losing everything plus the cost of the work shouldthe grafts not take.

As a result, every tree now in Belterra is a combina-tion of three separate individuals—firstly the nativeAmazonian stock, secondly the trunk grown from agrafted Oriental scion, and thirdly the resistant Ford-landia crown.

To save 2 million dying trees from 3 to 5 years old,8 million crown grafts were made. Happily for theAmazon territory, the combination of the right tech-nique and the right scions proved successful. Thus theeffort put into the Fordlandia plantation was notwasted; it was the failure there which produced themeans to save the Belterra plantations, and Fordlandiais the true cradle of the technique of double graftingrubber trees.

This salvage work was continued by the InstitutoAgronomico do Norte after its acquisition of theestate—worth more than 100 million cruzeiros—forthe nominal price of 5 million cruzeiros in December1945. The efforts to save Belterra achieved one hundred

Equatorial Forests

Tropical Forest

Araucárias Thickets

Caatingas

Thickets

Plains

Flood Plains

Littoral vegetation

Marshland

FIG. 5. Distribution map of native vegetation of Brazil.

per cent success despite the fact that the work wascarried out under difficult conditions, a little late andin what, for the purposes of rubber growing, is one ofthe worst climates in the Amazon territory. Today theplantation is a reserve source of latex, a nursery forthe stocking of new plantations, a teaching centre, atraining centre in plantation management andtechnology, and above all an object lesson in appliedscience and a proof of human capacity in the face ofa demanding and ill-understood task on the largestscale.

Belterra is also a centre of civilization in the Amazonterritory: in the heart of the equatorial belt, its indexof infantile mortality is twice as good as that in thecapital of Brazil or in the capitals of any of the Brazi-lian States.

The abandoned Fordlandia plantations have becomean animal breeding centre with a fine pedigree Nelloreherd of 1,300 head. Those parts of the rubber planta-tions worst affected by "leaf disease" and part of thevirgin jungle have been converted into pasture sownto elephant grass and two varieties of Guinea grass(Panicum altissimum Le Conte and Panicum maximumJacq) ; the total area involved is 800 hectares.

International Institute of the Hylean Amazon

The life of this institute was unfortunately short. InBrazil it came under heavy fire.

By a decision of the Brazilian Government, theInstituto Agronomico do Norte offered, as its specialcontribution, to hand over its whole plant either tothe proposed International Institute of the HyleanAmazon or to the Inter-American Institute, to securethe establishment of their headquarters in Brazil;however, the offer was not accepted.

Amazon Territory Economic Development Inspectorate

This is a body recently set up by the Federal Govern-ment with 3 per cent of the total federal tax revenueby way of working funds. It is doing what it can toassist agricultural and sociological research and develop-ment, but lacks adequate freedom of action. It shouldhowever be mentioned that the Instituto Agronomicodo Norte has received funds from the Inspectorate forthe execution of certain schemes of work, and thishelp has been extremely useful.

Amazon Territory Research Institute

This is a body under the National Research Council;it started operations in 1954. It made a bad beginningby setting up overlapping agricultural research ser-vices ; and being in an easy position as regards finance,it tempted a number of specialized technologists awayfrom the Instituto Agronomico do Norte, to the detri-ment, initially, of the latter's research work.

Fortunately, the new Directorate of the NationalResearch Council has decided to put a stop to theoverlapping, and from 1956 onwards the Amazon

Territory Research Institute will be required to providefinancial assistance for the Instituto Agronomico doNorte and centralize all agricultural research under thelatter's sole control in those sectors where it is alreadyactive. Its implicit principle that it is the duty ofricher and better-equipped bodies to back up thosedoing genuinely valuable work against odds makes thenew policy of the National Council eminently praise-worthy.

U.S. Department of Agriculture

In its early days the Instituto Agronomico do Nortewas afforded invaluable scientific co-operation by theU.S. Department of Agriculture in the shape of staffto reinforce the technical personnel of the Brazilianbody.

Interlocking between seconded North Americantechnologists and their Brazilian confrères was perfect;and rubber research, the establishment of technicalsections in the Instituto Agronomico do Norte and theformation of the institute's library were set on soundlines by experts jointly selected by the U.S. Departmentof Agriculture and the institute's directorate. Currentlythe maintenance of similar co-operation has passedinto the orbit of the Brazil-U.S.A. Office of AgriculturalTechnology (ETA).

Rockefeller Foundation

Over and above its excellent biological and taxonomicresearch on the mosquito vectors of malaria, its workagainst yellow fever and its current research on theviruses of diseases affecting man, the RockefellerFoundation has given the Instituto Agronomico doNorte invaluable assistance in the shape of grants toits technologists for study abroad, and more particu-larly to the writer, as Director of the Instituta Agrono-mico do Norte, for the import into the Amazon territoryof a pedigree Red Sindhi herd from Pakistan, whichwould have been impossible but for the $2,000 grantreceived from the foundation. Today, Brazil hasthe largest pedigree herd of the breed in the NewWorld.

The import of the original stock was strongly opposedby certain ill-informed elements; nevertheless it wassuccessfully carried through, and the American con-tinent owes the introduction of the Red Sindhi breedto the aid afforded to the Instituto Agronomico doNorte by the Rockefeller Foundation.

Food and Agriculture Organization of the United Nations

Of recent years, FAO has been pursuing a number ofextremely interesting lines of research in the Amazonterritory.

Notable items are its forest surveys undertaken todiscover sources of cellulose and exploitable precioustimbers.

Its study of the utilization of tropical soft woodspecies for paper-making is of great importance to the

Rapport sur la région amazonienne

region, and more important still are the experimentsit is conducting on afforestation with species suitablefor pulping to ensure supplies for any paper-millswhich might open up in the Amazon territory.

At the request of the Amazon territory EconomicDevelopment Inspectorate, FAO appointed threeexperts to afford it scientific assistance—a zoologist,an expert in tropical agriculture, and a soil scientist.

Rapport sur la région amazoniennepar

le Dr Felisberto C. Camargo

Résumé

L'Amazonie, qui couvre à elle seule environ 5 millionsde kilomètres carrés, constitue la plus importanteréserve continentale de terres et d'eaux susceptiblesd'être exploitées par l'homme.

La sagesse populaire distingue deux sortes de terres :les plaines basses (várzeas), exposées aux inondations, etles terres fermes (terras firmes) qui sont à l'abri des crues.

Les terres basses de l'estuaire de l'Amazone qui sontinondées par la mer et non par le fleuve pourraienttrès facilement être rendues utilisables. Il suffirait depratiquer tous les deux cents mètres, perpendiculaire-ment au cours d'eau, une tranchée ayant deux mètresde largeur à la base. Ces tranchées assureraient l'écou-lement de l'eau de mer à marée haute. Cette méthodede drainage appliquée aux plaines basses en borduredu Guama, par l'Institut agronomique du Nord (Belém),a permis d'obtenir 3 000 à 3 500 kilogrammes de rizà l'hectare, pendant la saison des pluies.

Dans le cas des plaines basses de l'intérieur del'Amazonie qui sont périodiquement inondées par lefleuve, à la saison des pluies, on se propose de creuserdes canaux de colmatage capables de provoquer laformation de dépôts sédimentaires, en dérivant leseaux de l'Amazone en crue vers les lacs riverains. Ilexiste actuellement six canaux de colmatage en Ama-zonie. L'œuvre de colmatage entreprise dans le bas

Amazone vise à créer des terres qui se prêtent à l'exploi-tation agricole, grâce à un système de polders adaptéaux conditions des régions tropicales humides.

La densité moyenne démographique est d'un habi-tant pour deux kilomètres carrés. Un sixième de lapopulation de l'Amazonie est concentré à Belém et àManaus; un tiers pratique la culture itinérante, lamoitié végète dans les exploitations de caoutchouc dela forêt. Actuellement, l'Amazonie a besoin d'immi-grants pour développer sa production de denrées ali-mentaires.

L'Amazonie a un climat humide à peu près uniforme.Il existe cependant une zone moins humide qui s'étenddu nord au sud de la vallée du Trombetas au bassin duTapajós et du Xingu.

Les organismes de recherches agronomiques quis'intéressent à l'Amazonie sont les suivants : le muséeGoeldi, créé par le gouvernement de l'État du Pará;l'Institut agronomique du Nord, créé par le ministrede l'agriculture du gouvernement fédéral brésilien; laDirection du développement de l'Amazonie; et l'Ins-titut de recherches sur l'Amazonie. Ajoutons à cetteliste des organismes extérieurs tels que la FondationRockefeller, l'Organisation des Nations Unies pourl'alimentation et l'agriculture, qui ont apporté leurcollaboration à des institutions locales.

Bibliography/Bibliographie

1. CAMARGO, F. C. Sugestões para o soerguimento economicodo vale Amazónico. Belém, Estado do Pará, Brasil,Instituto Agronomico do Norte, 1948.

2. . Terra e colonização no Antigo e Novo Quatennàrioda zona da Estrada de Ferro de Bragança. Estado do Pará.

3. . Contribuição apresentada a Conferência Inter-Americana de Conservação dos Recursos Naturais Reno-váveis, Denver, Colorado, Estados Unidos. Published inthe Boletim do Museu Goeldi, no. 70, Belém, Estado doPará, Brasil, 1948, off-print.

Problems of humid tropical regions ¡Problèmes des régions tropicales humides

4. . Reclamation of the Amazonian flood-lands nearBelém. Abstract. Reprint from Proceedings of the UnitedNations Scientific Conference on the Conservation andUtilization of Resources, Lake Success, New York, 1949.

5. . "A escola e o problema das várzeas". An addressdelivered at the laying of the foundation-stone of themain building of the Escola de Agronomia da Amazonia,27 December 1952.

6. . "Dados referentes aos Ganais de Colmatagem naEstção Experimental do Baixo Amazonas". From4 November 1953 to 15 September 1955.

7. . "Colmatagem natural e conduzida", Bol. Agrie.,Departamento da Produção Vegetal da Secretaria daAgricultura do Estado de Minas Gerais, 1955.

8. CASTRO SOAKES, L. Limites meriodionais e orientais daárea de ocorrência da floresta amazónica em território brasi-

leiro. Instituto Brasileiro de Geografia e Estatistica, 1953.9. DUCKE, A.; BLACK, G. A. "Notas sobre a fitogeografia

da Amazónia Brasileira", Bol. téc. Inst, agron. N., no. 29.

10. GOUROU, P. "Observações geográficas na Amazonia",Rev. Bras. Geogr., no. 2 and 3, off-prints, Part I andPart II, 1949-1950.

11. . The tropical world. Transi, by E. D. Laborde,1953.

12. JUNQUEIRA SCHMIDT, Jose Carlos. O clima da Amazonia,Instituto Brasileiro de Geografia e Estatistica, off-printfrom Rev. Bras. Geogr. 1947, no. 3, year IV.

13. KOEPPEN, W. Climatologia. Mexican edition, transi, byPedro Hendrichs Pérez, 1948.

14. SEREBRENICK, S. "Notas sobre o clima do Brasil", Bol.Minist. Agrie. 1945, off-print.

15. SILVEIRA, A. O arroz e a juta no vale do Rio Guarna.Estado do Pará; Comissão de Finanças, 15 June 1949,Senado Federal, Brasil, Imprensa Nacional, 1949, off-print.

16. SlOLi, H. "Nota sobre a sedimentação na várzea doBaixo Amazonas", Bol. téc. Inst, agron. N., June 1951.

Report on the Caribbean Regionby

Dr. Enrique Beltran,Instituto Mexicano de Recursos Naturales Renovables,

Mexico

INTRODUCTION

DELIMITATION AND LOCALIZATION"CARIBBEAN REGION"

OF THE

By "Caribbean region" we understand in this reportthe tropical area north of the equator, enclosing thepart of the Atlantic Ocean known as "Caribbean Sea",bordered on the mainland by the shores of the south-eastern tip of Mexico, the narrow strip of CentralAmerica, the Atlantic coast of Colombia and a smallpart of Northern Venezuela. On the north and eastof this area lies the group of islands known as theAntilles, forming a loose arc.

Mexico, Colombia and Venezuela must be includedwhen talking about the Caribbean region, althoughonly a small part of those countries may be properlyconsidered as belonging to the region. Central America,though it has also a Pacific coast, may be consideredto belong to the Caribbeans, on account of the narrow-ness of the isthmus in which it is situated ; we includealso the Republic of El Salvador, even if this smallcountry is the only one in Central America with nocoastline on the Atlantic, because of its many simi-larities with other portions of the zone. And in relationto the Antilles all these regions, with no exception,are truly Caribbean in character.

For practical reasons, this account is divided intothree parts: Mexico, Antilles, and the Central andNorthern Regions of South America. But as manybasic problems are similar in all the areas surveyed,a fourth part is included to offer a panoramic view ofthe whole "Caribbean region".

At the end a selected list of references gives detailedand first-hand information in regard to the differentitems discussed in the report. No attempt has beenmade to separate such references by region; they arearranged alphabetically by author's name. Mo6t ofsuch references indicate in the title the general orrestricted area covered by them; in a few cases, where

the title offers no clues, the geographical limitation ofthe text is indicated, within brackets, at the end ofthe reference.

MEXICO

HUMID TROPICS. GEOGRAPHICAL SURVEY

More than 50 per cent of Mexican territory may beclassified as arid and semi-arid lands, and some of therest belongs properly to the temperate and cold zones;but the extreme south and south-eastern parts, as wellas a short fringe on both coasts—Atlantic and Pacific—extending more or less northward like the branches ofa "V", have a combination of high temperature andsufficient rainfall that permits their inclusion as "humidtropics". Part of this region—eastern Yucatan and allthe territory of Quintana Roo—has shores on theCaribbean Sea.

Although many of the Mexican humid tropics—thestates of Chiapas, Veracruz, Tabasco and southernCampeche—are lowlands with large rivers and exten-sive marshy areas, those bordering the Caribbean Seahave a unique feature: they almost completely lackrunning surface water. The ground is of limestone,highly porous, and the rains falling there go downquickly to accumulate in underground deposits.

Altogether the parts of Mexico with an annual meanrainfall of more than 1,500 millimetres cover about133,500 square kilometres, or 6.8 per cent of the terri-tory, and some of them are on the Caribbean, wherethe mean rainfall varies from 1,200 to 1,500 millimetres.Following Kceppen's classification, the prevalent cli-mates are Aw', Amwg, Awg and Awgi. The latter arethe more important in this report, because they arefound in those parts of Mexico on the Caribbean Sea.Of course if we use Thornthwaite's classification the

1. This report attempts to give a bird's eye view of the situation in the Carib-bean, and offers an extensive bibliography, where detailed informationmay be found by those interested.

area is considered as Cr A'a', which cannot be calledhumid tropics.

Meteorological observations have been kept for yearsin Mexico and, based on them, many schemes of climateclassification have been proposed; specially interestingare those of Contreras-Arias [60]1 and of Gomez andVivo (1946); the former uses Thornthwaite's and thelatter Kceppen's methods for the presentation of data.Special climatic studies of tropical places, exceptrestricted ones undertaken to answer practical problemsin agricultural or irrigation projects, are lacking. Nospecial research on microclimatology has been carriedout, and experimental work, for instance evapo-transpi-ration measures, as required in Thornthwaite's, isurgently needed in the Caribbean Zone.

The geology of the area has been studied by severalauthors. The peninsula of Yucatan has been the subjectof a detailed study by Sapper [237], and later byRobles Ramos [226]. Recently Guzman, Suarez andLopez Ramos [116] have published a general accountof the geology of eastern Mexico, with special referenceto oil prospecting, in which is included the area underconsideration here. The late Professor Muellerried wrotea very good geological account of the State of Chiapas,but it has not been published.

No special geographic study of the zone has yetbeen made, although the basic data are included insuch general works as that of Tamayo [278] and others.Acceptable maps are available for all the tropicalregions; and some much more detailed for smallerareas. But there is still a great deal of work to be donein this respect. Worthy of mention is Herrera's [125]study of the Rio Hondo, which separates Mexico andBritish Honduras.

The Atlantic tropical region has been handicappedin its land communications by swampy conditions inmany parts. But there are good roads connectingVeracruz with the rest of the country. And the railwaysystem, which has long been very good in Veracruz,and has several lines in Campeche and Yucatan, hasnow been extended to connect the latter state withthe nation's capital. Moreover, in addition to therivers in Veracruz, Tabasco and Campeche, severalrivers such as the Papaloapan, Grijalva, Usumacinta,Matamoros and others, offer good facilities for watertransport.

The Pacific side is well served by the Pan-Americanroad, connecting Mexico with Guatemala, as well asby a railway.

But the parts directly bordering the Caribbean—namely the territory of Quintana Roo—have poorcommunications, and several places can only be reachedby aeroplane or on horseback.

Population is very scanty in Quintana Roo, with adensity of 0.54 inhabitants per square kilometre; inYucatan—which is not really a humid tropical region—the density rises to 13.42 per square kilometre; but inCampeche, which adjoins Quintana Roo and also

records high temperatures and humidity, the figure,though higher than in Quintana Roo, amounts onlyto 2.40 per square kilometre.

Sufficiently accurate population censuses have beentaken in Mexico for a long time; the last was in 1950,and the results are already published.

In the whole of the peninsula of Yucatan—the onlytruly Caribbean region—the Indian population is ofMayan stock, fairly pure in many places, although inmost parts they have interbred extensively. In all theother regions of the Mexican humid tropics, the differ-ent Indian groups have more or less interbred withwhite people.

SOIL AND WATER

Water is the principal limiting factor in Mexican life.According to Garcia Quintero [98], 52.1 per cent of theterritory receives less than 800 millimetres annualrainfall and may be classified as arid; 30.6 per centhas between 800 and 1,200 millimetres and may beconsidered semi-arid; 10.5 per cent with 1,200 to1,500 millimetres is included under the heading of semi-humid; and only the remaining 6.8 per cent with morethan 1,500 millimetres annual rainfall, may be properlyconsidered humid.

The last two categories are included in that part ofMexico commonly called "hot land" (tierra caliente)and part of it is in the Caribbean area.

Even where a sufficient total rainfall is registeredduring the year, most places have only a heavy rainyseason and a long dry season. This creates big problemsin the exploitation of the land, especially in agricul-ture.

A larger irrigation programme has been in operationfor the last 25 years, and Mexico is doing much tobring under cultivation some of her arid and semi-aridlands.

In the small part with a really humid climate, likesome parts of southern Veracruz, Tabasco and Chiapas,the problem is just the opposite: it is necessary to drainsuch soils, in order to put them to any productiveuse.

Along the Caribbean shore proper the situation ispeculiar, for although the rainfall is considerable, thepermeable character of the limestone ground and thelack of slope do not permit the formation of rivers.The only one which empties into the Caribbean isRio Hondo, marking the boundary between Mexicoand British Honduras.

Using Thornthwaite's method of potential evapo-transpiration calculations, we see [60] that the northernpart of Yucatan peninsula shows a water deficiencyof the order of 200 to 400 millimetres; and that therest—including the part on the Caribbean coast—ison the limits of water balance.

1. The figures in bracketB refer to the bibliography on page 36.

Report on the Caribbean region

Most of the rest of the southern and south-easternportion—Veracruz, Tabasco, Chiapas—have a positivewater balance, reaching in some places more than 1,000millimetres.

The soils of the Yucatan Peninsula are classified asterra-rosa, gley and rendzina; lateritic and chernozemsoils are found in some localities of the humid tropicalregion.

According to the map produced by the ConservationFoundation and FAO [59], the soils of the tropicalhumid regions may be considered as uneroded in Quin-tana Roo and in most of Campeche as well as in Tabascoand Chiapas; slightly eroded in Yucatan and part ofCampeche, and severely eroded only in some parts ofeastern Chiapas and northern Tabasco.

Until very recently, no good scientific study of thesetropical soils—with modern techniques—had beenmade. But Aguilera (1955), working on a project ofthe Instituto Mexicano de Recursos Naturales Reno-vables, has started a very careful survey of the edapho-logy of the peninsula of Yucatan and adjoiningstates.

Most of the soils in the Mexican tropics are at presentcovered by forest vegetation. As these regions are lesspopulated, and have more water than the highlandplateau, many people look upon them as a potentialagricultural reserve of great value. Knowing the greatfragility of tropical soils when exposed to atmosphericagents without their natural vegetation cover, it isessential to study them carefully before any move ismade to alter their present conditions.

FORESTS AND FORESTRY

The great traveller Humboldt estimated at the end ofthe eighteenth century that Mexican forests covered50 per cent of the then Nueva España territory. Today,recent estimates point to a proportion of around 13 percent of the nation as covered by forest.

Garcia-Martinez [96] calculated tropical humid andsemi-humid forests at 19,203,467 hectares; 15 yearslater Dupré [81] estimated the area of forests of leaf-bearing trees as 14,877,037 hectares. The truth is thata good forest inventory employing modern aerial photo-graphy has not yet been carried out in sufficient detail,and our knowledge of the situation is by no meansaccurate.

Leopold [158] presents a map of Mexican vegetationthat shows the southern part of the Yucatan Peninsula,as well as parts of Chiapas, Tabasco and SouthernVeracruz, covered by rain forest. The north of Yucatanand most of the Veracruz coast belong to tropical ever-green forest classification.

Problems of the Mexican forests have been studiedby Gill [102, 103], Huguet and Verduzco [143] andBeltran [22], revealing their great potential wealthand, at the same time, the many problems involved ingood forest management there.

Under Spanish rule, the most important species ofMexican tropical vegetation was the dyewood (Haema-toxylum campechianum); with the advent of anilinedyes the importance of this tree almost vanished, butthe demand for chewing gum has given great impor-tance to zapotilla (Achras Zapota). Today quite animportant lumbering industry has developed in thesouth and south-east of Mexico, specially using maho-gany (Swietenia macrophyla) in the more humid regions,and Spanish cedar (Cedrela mexicana) in the less humidtropics.

Although commercial stress is now focused almostexclusively on these "precious" species, there aremany more in Mexican tropical forests with a greatfuture. The more pressing problems today are to findgood methods of artificial regeneration, and to deter-mine the possibilities of many species not at presentof commercial value.

AGRICULTURE

Although the proportion of good agricultural land inMexico, with acceptable pedological, topographicaland climatic characteristics, is not large—and wateris a severely limiting factor—the country may beconsidered as predominantly agricultural. The censusfigures of 1949 showed that 64.9 per cent of personsconsidered as economically active were engaged inagriculture.

Traditionally, Mexico has devoted most of its pro-ductive soil to subsistence crops, especially corn (Zeamays), beans (Phaseolus) and chili (Capsicum annum),which constitute the basic staple food of the popu-lation.

In modern times some cash crops have grown well,and are now an important factor in the economicbalance of the country. Among these are coffee, cotton,sugar cane, cocoa and henequén.

Coffee is mostly grown at moderate altitudes, cocoain the lowlands of Southern Mexico. Cotton, originallya tropical crop, has now spread to many other places;sugar still finds very good conditions in the humidtropics. Henequén is the principal crop of northernYucatan.

Bananas were formerly the foremost crop of suchtropical humid regions as southern Veracruz andTabasco, but the spread of severe diseases has playedsuch havoc that it is now relegated to a secondaryplace.

As corn and beans are the basic food of Mexicans,special attention has been given to them; and, althoughoriginally plants of temperate regions, many goodvarieties are now grown at low altitudes in humidtropical places.

Until quite recently, most agricultural scientificresearch was carried on in the temperate zone. Butthere are now good experimental stations located inthe humid tropics; among them, those of Rosario

Problems of humid tropical régions/Problèmes des régions tropicales humides

Izapa, at Chiapas, Cayal, at Campeche and Cotaxtla,at Veracruz, are worthy of mention.

ANIMAL BREEDING

Cattle are bred for export to the United States of Americaas young calves, or as packed or refrigerated meat,or to meet the local demand for meat, milk and otherproducts.

The northern states, with very large grazing areas,but with a semi-arid climate and severely short ofwater, have always been a region where cattle arebred and then sent across the border to fatten in UnitedStates territory. The middle states supply most ofthe demand of the big cities in the central plateau.There is also an area in the south and south-east wherecattle is raised mostly for local consumption.

Most of the cattle raising is done under primitiveconditions, without much care for stock improvementor forage crops. In some places the capacity of theland to sustain animals is very low, but lack of pro-ductivity is in some measure compensated by theextended areas used.

In 1946 foot and mouth disease invaded the countryand killed a lot of animals. It also seriously affectedthe economy of cattle raising, owing to the closure ofthe United States frontier to cattle imports. Thenorthern states of Mexico were seriously affected.

The campaign to eradicate foot and mouth diseasewas very difficult, but was carried out most success-fully. Not only quarantine measures, but also the resultsof scientific investigation to develop an active vaccine,were responsible for this success.

Besides cattle, other animals are bred in Mexico. Insome places goats are so abundant that they constitutea major threat to soil conservation.

In the humid tropics, better grasses as well as morewater may seem to favour animal breeding. Unfor-tunately, pests and diseases of different sorts militateagainst the industry. Ticks are among the worst enemiesof cows in these parts.

Hitherto, most attempts to import better animals totropical areas have met with complete failure becausethe animals are not resistant to local diseases. Theresult is that very little significant improvement hasbeen achieved here in the field of animal breeding.

FISHERIES

With a coastline of nearly 10,000 kilometres, both onthe Pacific and Atlantic oceans, Mexico would seemto offer excellent conditions for the fishing industry.Unfortunately, this has been until recently one of theless developed branches of the national economy.

Fishing has always been on quite a small scale. Mostof the big tuna fishing in the Pacific—namely in theGulf of California—is done by United States fishermen,with very little profit to the Mexican economy.

In the Gulf of Mexico, fishing was carried on, untilvery recent times, to supply the markets of the bigcities of the interior. The demand was small, for Mexi-cans are not great fish-eaters. In the last ten years,however, the discovery of very rich giant shrimp bankshas promoted an increased interest in fishing for thiscrustacean, which fetches very good prices and isalmost all exported, frozen, to the United States ofAmerica.

Recent investigations in the Gulf of Mexico show thepossibility of catching tuna in this area. If this isconfirmed, and the necessary capital raised, this newindustry would offer big possibilities.

In regard to sea fisheries, all Mexican waters are oftropical character. And the fishing industry here facesthe same basic problem as in similar places: a largenumber of species, but all of them represented bysmall numbers.

In recent times, much stress has been laid by Mexicanauthorities on promoting inland pisciculture, side byside with agriculture, as a way to improve peasantnutrition, which, in general, is not very rich in animalproteins.

NUTRITION AND DISEASES

Nutrition in the tropical part of Mexico, as in otherparts of the country, is mostly of vegetable character,obtained specially from corn and beans, the staple foods.

However, in many of these tropical regions, fruit—bananas, mangoes and others—is abundant, andsupplements the daily diet of the people.

In some of these lands, too, the ocean is near, andfish and crustaceans furnish animal proteins of highvalue. In some places, too, for example in Yucatan,hunting is practised extensively, and wild animals,such as deer and indigenous pheasant, are frequentadditions to the rural tables.

In the last 10 or 15 years, great interest in nutritionresearch has been developed through the Institute ofNutrition, which forms part of the Ministry of PublicHealth. The attention of the institute has been givenmostly to determining the real value of the commonestMexican foods; as well as to an extensive survey tofind new appropriate sources of food in natural pro-ducts, or in plants that may be easily cultivated.

In regard to diseases—and it is difficult to determinewhich are truly "tropical"—the most important ismalaria. However, this very year a big campaignaimed at eradicating this disease has been launched bythe authorities, employing contact residual insecticides,and there are good grounds for hope that malaria maysoon be extinct.

In 1939 an Institute of Public Health and TropicalDiseases was established, to deal especially with diseasesprevalent in the hot and humid part of the country. Avery good resume of the state of tropical diseases inMexico has recently been given by Martinez Baez [174].

ANTILLES

GEOGRAPHICAL SURVEY

The Antilles or West Indies constitute a chain of largeand small islands, which extends from Cuba, the largest,to Trinidad, lying near the Venezuelan coast.

A distinction is usually made between the Greaterand the Lesser Antilles. Cuba, Puerto Rico, Hispaniola(including Haiti and Santo Domingo) and Jamaicaconstitute the former. The latter comprise a chainclosing the southern end of the Caribbean Sea; themore important of the islands in this chain are: Guade-loupe, Dominica, Martinique, St. Lucia, Barbados,Grenada, Tobago and Trinidad.

Cuba, Haiti, and Santo Domingo are independentcountries. Puerto Rico (now an associate state of theUnion) and the Virgin Islands belong to the UnitedStates of America. Under the rule of Great Britain area large number of islands, the more important beingBahama, Jamaica, Grenada, Barbados, Tobago andTrinidad. Guadeloupe and Martinique are French-administered. Curaçao and Aruba belong to the Nether-lands, and Margarita and La Tortuga to Venezuela.

Geologically, and in regard to their present physicalstructure, the West Indies islands differ among them-selves to some extent. A partially submerged mountainchain seems to be the outstanding feature. In most ofthem we find rings of coral reefs around the shore, someof them quite large. The Greater Antilles, on accountof their size, have quite different physiographic struc-tures. In the Lesser Antilles, it is possible to separatethe low-lying Barbuda, Antigua, Grande-Terre, MarieGalante and Barbados from islands with moderatelyhigh mountains, such as Guadeloupe, Dominica, Marti-nique, St. Lucia, St. Vincent, Grenada and Tobago.Mt. Soufrière, 1,484 metres, on Guadeloupe, is thehighest mountain in the Lesser Antilles.

Some of these mountainous islands, of volcanic origin,have still active volcanoes; the eruption of Mt. Pelee,at Martinique, in 1902, with a total loss of 40,000 humanlives, is still remembered as one of the biggest.

The climate of most of the West Indian islands,although warm, may be considered comfortable, sincetheir small size permits them to be freshened by tradewinds. The average annual rainfall varies greatly inthe different islands: even in different parts of someof the Greater Antilles, we find great variations, forexample in Jamaica, where Kingston—the capital—receives only 625 millimetres; but the Blue Mountains,some thirty miles away, get more than 5,500 milli-metres.

Most of the Antilles have two rainy seasons in ayear; one starting in May and the other in October.But some have only one, as in Jamaica, from June toDecember, followed by a dry season of five months.

A climatic characteristic of the Antilles is the fre-quency from August to October of violent tropical

cyclones. In 1955, these hurricanes did great damagein the Antilles and along the continental shore of theCaribbean, the most destructive being the Hilda andthe Janet. These winter cyclones greatly affect agri-culture and oblige the inhabitants to take measures tocounter their effects.

Population density, which is considerable in mostof the West Indian islands, has greatly disturbed thenatural vegetation. Most of the terrain is today devotedto agriculture or cattle raising, but there are still signsof the original phyto-geographic character of the vege-tation.

SOIL AND WATER

Cuba has more than half of its level land well drained,except for swampy areas on the coast. Rainfall is ingeneral sufficient and well distributed throughout theyear, being heavier in the western part. Most of thecentral parts of the island show little or no signs oferosion, but both eastern and western extremitiescontain severely eroded places.

The island of Hispaniola has level land only alongthe south-eastern tip and in the narrow strips of Cul deSac, Plain du Nord, the Cibao and the Artibonitebasin.

Although rainfall is in many places not scarce, mostof the island suffers from humidity deficiency in termsof agricultural requirements and needs irrigation forsugar cane cultivation. The eastern end is hardlyeroded at all; moderate erosion is seen in the centralpart; and more advanced and severe erosion affectsthe western part, covering most of Haiti.

Puerto Rico is predominantly mountainous, and thelittle level land that exists lies mostly along the northand south coasts. Rainfall in the mountains amountsto 2,500 millimetres in some places, but only to 1,500near San Juan, and drops to 900 on the south-westcoast. Much of the island shows moderate erosion.

Jamaica has most of its land area occupied by ahigh limestone plateau of rugged surface, deeply cutby streams. Although places in the Blue Mountains,located at the eastern tip, have a rainfall of 5,000 milli-metres, elsewhere it is not sufficient to permit muchcultivation. Moderate erosion, a little less severe thanin Puerto Rico, is to be seen in all parts of the island.

Trinidad has high mountains in the north, low hillsto the south, and level land in the middle, with moderateerosion and a rainfall that may reach 3,750 millimetresin the eastern part, but decreases to 1,250 millimetresalong the west coast.

Guadeloupe is mostly mountainous in the west, butlow-lying in the Grande-Terre part; Martinique ismostly mountain land with plains in a pocket alongthe west coast. Both, as well as most of the LesserAntilles, show signs of moderate erosion.

Forests in the West Indies were of great extent andvalue before the white man came. But today, whetherfor commercial reasons, i.e., the exploitation of valuablespecies, or because population pressure forces moreforest to be cleared for agricultural purposes, they aremuch reduced.

Cuba was originally almost entirely covered by trees,but cattle raising first, and sugar cane cultivation later,have led to their extinction; today only 16 per centof the island's territory is under forest. Many speciesare used for domestic consumption, and mahogany(Swietenia mahogany), Spanish cedar (Cedrela mexicana)and lignum vitae (Guaiacum) are exported.

Hispaniola also has lignum vitae, mahogany andcedar, as well as Cecropia—called bois trompette inHaiti—in the more humid parts. High up in the moun-tains, Pinus occidentalis and Juniperus locayana are found.

Puerto Rico has been almost entirely cleared foragriculture, but it has a very valuable timber in Magnoliasplendens. The Tropical Forest Experiment Station, ofthe United States Forest Service, has been located inPuerto Rico since 1939, and fine tropical forestry workhas been done there.

Although Jamaica has been severely deforested, itstill has important timber, and many species are utilizedfor domestic consumption. There is some export ofmahogany (S. mahogany) and lignum vitae. Localstudies show the existence of more than one hundredtree species of potential commercial value.

Trinidad once supported heavy tropical rain forest,now very much reduced. There is still good red cedar,of which some is exported. On Trinidad, at the ImperialInstitute of Agriculture, fine experimental work onartificial regeneration of rain forest has been done formany years. It is now one of the most importantcentres in that field.

The islands of Guadeloupe and Martinique have goodforests, and have been the centre of experimentalforestry work carried out by French foresters; compa-rison of techniques there with those developed by theBritish in Trinidad, and by the USFS at Puerto Ricowould show interesting contrasts.

In recent years, use has been made of some localWest Indian plants as secondary sources of rubber,of importance in emergencies. A programme was alsolaunched to encourage cultivation of the Pará rubbertree (Hevea brasiliensis), which although originally acontinental plant, prospers well in the Antilles.

AGRICULTURE

Not one of the islands of the West Indies is of industrialcharacter; all are truly agricultural countries. But theconditions for agriculture, and the final destination ofproducts, differ.

In pre-Columbian days, most of the islands had small

indigenous populations, of low cultural level, whichpractised a very primitive agriculture.

With the advent of the Europeans, most islandswere converted to agricultural centres to produce suchcommodities as sugar and tobacco, which found readymarkets in the Old World.

Today, sugar-cane cultivation is the most importanteconomic activity of Cuba and Puerto Rico, whichexport the product to the United States of America.Some sugar-cane is also grown in other islands both ofthe Greater and the Lesser Antilles.

Wherever sugar - cane cultivation has economicimportance, serious problems arise, mainly on accountof the labour force needed for part of the year, and forwhich it is not possible to find occupation in otherseasons. That situation has promoted migration fromthe more populous areas to those where sugar-cane isextensively grown; but as most of the West Indies isalready densely populated, these countries only allowtemporary migration for the sugar harvest; afterwardsthe workers return whence they came.

Another important crop on some of these islands,for instance Jamaica, was bananas. But in recent times,diseases affecting that plant have reduced its cultiva-tion and caused it to be replaced by other crops.

All the same, bananas are an appropriate crop forsuch areas, and a great deal of research and experimen-tation is carried on to find new varieties resistant todiseases, or to develop remedial methods.

In drier parts, e.g. on the Cuban coast, henequénhas been grown with some success. Of course, all theAntilles have areas devoted to subsistence crops,mostly rice, corn, and manioc.

Agricultural problems have seriously preoccupiedthese parts, and there are centres devoted to researchand experiment. Among the more important are theAgricultural Experiment Station at Las Vegas, Cuba;the Agricultural Stations in Puerto Rico; and theImperial Institute of Agriculture, in Trinidad.

ANIMAL BREEDING

Cattle raising was among the more important occupa-tions of the West Indies, during the first years afterthe advent of the Europeans. As there were not manygold or silver mines—the principal attraction to Spa-niards in Mexico and Peru—they turned to cattleraising in the larger states. An exception was SantoDomingo, where the Spaniards were quick to find goldin the river beds.

Even in some almost unpopulated islands, the sailorsset free certain domestic animals that bred extensivelyand later constituted important sources of food. Thename boucaniers, given to certain pirates in that area,was due to their habit of landing on some of theseislands, killing the cattle, which had returned to wildconditions, and drying their meat on open grills calledboucans.

Cuba was principally a cattle-raising country in earlytimes, and only changed with the expansion of sugarcane cultivation, mostly after the Independence. Todaygreat efforts are being made to restore the earlier sourceof wealth. The principal problem is the absence ofgood leguminous plants, but a programme is on footto introduce foreign species.

At Puerto Rico, the limitation of space and of avail-able pastures has been a serious handicap to animalhusbandry. But great concentration, and the applica-tion of good scientific techniques developed in theUnited States of America, are now introducing intensiveexploitation to cover the deficiency of meat, milk andderived products, many of which are now imported.

In Jamaica, cattle raising is better, and grazing landalmost equals the area sown with crops. An extensiveprogramme of grass seeding, using mostly Guinea grass(Panicum maximum), is in operation.

Throughout the West Indies, animals are bred tomeet the needs of local populations. But the industryis nowhere of importance and lack of interest in thisbranch of land utilization has hindered the develop-ment of scientific research.

FISHERIES

Their insular character naturally furnishes the Antilleswith all the necessary conditions for the developmentof a good fishing industry.

Almost everywhere, fishing provides food for thecoastal inhabitants as well as for the mostly smalltowns of the interior.

D'Alarcao [2] gives the following figures of catchesduring 1951: Cuba, 10,000 tons; Puerto Rico, 2,500 tons;Haiti, 2,100 tons; Dominican Republic, 650. In regardto export, the only available figure is for Cuba, with1,154,000 U.S. dollars (1951).

Efforts to promote the fishing industry in this areaincluded the holding of a Fishing Conference at Trinidadin 1952.

As far as our information goes, the only fisheryresearch centre in the Antilles is in Cuba, where formany years the Fisheries Department has operated aLaboratory of Fisheries Research, and, recently, anew and larger Institute of Fisheries.

Although conditions in this respect, as in many others,vary much from one island to another, most of theWest Indies suffers from over-population. Accordingto United Nations statistics for 1951, Santo Domingowith 44 inhabitants per square kilometre, or Cubawith 48, compare very favourably with Jamaica's250 or Puerto Rico's 253.

This density of population, in industrially under-developed countries, may cause an insufficient foodsupply for the people, and that is the case here.

The basic staple foodstuffs in these parts are rice,manioc, corn, beans and tropical fruits like bananas.In some places these are supplemented by meat—beefor pork. Almost everywhere fish and shellfish arecaught by the consumer or bought at the local market.

As regards disease, it is very difficult to make a realdistinction between tropical and other diseases. Butcertain tropical diseases such as filariasis in PuertoRico, or yaws in Haiti, are prevalent among largegroups of the population. Yaws has been the subjectof a big eradication programme, using penicillin, withresults not yet fully known.

Every improvement in agriculture, fisheries andanimal breeding will greatly improve the nutritionconditions in the area, with a consequently reducedincidence of disease.

CENTRAL AND NORTHERN REGIONS OFSOUTH AMERICA

GEOGRAPHICAL SURVEY

The south and south-eastern parts of the CaribbeanSea are bounded by the isthmic part of the WesternHemisphere, including British Honduras, Guatemala,Honduras, Nicaragua, Costa Rica and Panama as wellas north-western Colombia and northern Venezuela.

British Honduras, surrounded by Mexico and Gua-temala, is a low-lying forest territory of 8,598 squarekilometres, with hills and low mountains in the south.

Central America proper is formed by the five inde-pendent countries above mentioned, as well as by theRepublic of El Salvador, lying south of Guatemala,which is the only country without a Caribbean coast-line. It faces the Pacific.

The general surface configuration shows a centralrange of rugged mountains, a continuation of the chainthat makes the continent's backbone. On the Caribbeanshore are lowlands, forming a narrow strip in Guate-mala and Honduras, becoming wider in Nicaragua andnorthern Costa Rica.

The prevalent climate along the coast is of the typeAm, Aw and Af—the last is encountered in a smallpocket on the borders of Nicaragua and Costa Rica—according to Kceppen's classification. The annual rain-fall along most of the shore line varies from 2,000 to5,000 millimetres except in the small pocket mentioned,where it rises to over 5,000 millimetres.

In Panama, the isthmus reaches its narrowest part;there is also a gap in the chain of mountains. Thesecharacteristics, together with the existence of swampsand small lakes, made possible the construction of thePanama Canal, connecting the Atlantic-Caribbean withthe Pacific Ocean.

There are several volcanoes—some of them stillactive—along the isthmic portion of the continent.Mention may also be made of several lakes, the biggest

Problems of humid tropical regions¡Problèmes des régions tropicales humides

of which is Nicaragua Lake; other big and interestinglakes are Lake Atitlan in Guatemala, and Lake Managuain Nicaragua.

The South American border of the Caribbean ismostly open plains in Colombia, with some mountainranges, like the Sierra Nevada de Santa Marta whichalmost reaches the coast. The big Magdalena Riverflows into the Caribbean. The climate is very muchinfluenced by altitude, being hot and wet in somelowland places, or semi-arid in the Goajira Peninsulaon the Venezuelan border.

The Venezuelan part is also lowland in many places,but the mountain chain runs parallel to the coast, atvery short distances away in many places, which makesthe climate quite different in places situated only afew miles apart.

Natural vegetation, although affected by humanaction, has not been so profoundly changed as in mostof the West Indies. British Honduras is wholly tropicalforest, extending southwards along the coast of Guate-mala as far as Panama. In the mountain highlands,temperate forest is found, with conifers stretching toLake Nicaragua. In Colombia and Venezuela, althoughthere are many places covered by selva or tropical wetforest, many drier parts are covered by tropical scrub.

SOIL AND WATER

Although there are remarkable differences in the soilsof Central America, according to the different usesmade of the land, it may be said generally that mostof the southern part, comprising Panama and CostaRica, as well as the shores of Nicaragua, Guatemalaand British Honduras, show little sign of erosion;erosion is more marked in the highlands of Nicaragua,Honduras and El Salvador; patches of severe erosionmay be seen on the border of Guatemala and Mexico,as well as along the coast of British Honduras.

On the Colombian coast erosion is slight or absent,except in the peninsula of Goajira, where it is severe.In the Venezuelan part the situation is worse than inColombia.

Most of the territory of Central America is made upof mountains or hills with only small valleys of economicimportance.

In many countries, as in El Salvador, the smallamount of level land, as well as the population density,have forced the peasants to cultivate the soil on thehills, and this is greatly accelerating erosion.

Owing to the rugged structure of the land, the soilsdiffer widely, and in many places we lack detailedknowledge of their characteristics.

The rain pattern in many places, with heavy showersduring the wet season, is calculated to cause erosionand, if agriculture expands, without proper conserva-tion measures, great damage to the soil may be expected.

Good soil surveys have been carried out by bigconcerns like the United Fruit Company, others by

local agencies. But there is still much to be done inthis respect.

Originally, Central America was covered by heavyforest of different types, from tropical rain ones toconifers, which extend from the Mexican border tothe edge of Lake Nicaragua.

Although forest destruction has been heavy, andwhat remains of forest land is only a small fraction ofthe original coverage, very little lumbering has beendone. Most of the destruction has been caused by theshifting system of agriculture, which burns great areasof forest every year.

Some virgin forests still remain, like those extendinginto Costa Rica from the Nicaraguan border.

Several valuable species are found in Central Amer-ican forests, for instance mahogany (Swietenia macro-phyla), red cedar (Cedrela mexicana), cordia wood(Cordia spp.), rosewood (Tabebuia Donneili), cocobolo(Dalbergia retusa and other species), lignum vitae(Guaiacum officinale). Some of these are now the subjectof lumbering operations, mostly on a small scale. Butthere are many other valuable woods in Central Amer-ican forests that are not used now, but may be ofeconomic interest in the future.

Conifer forests, mostly Pinus oocarpa and P. caribaea,extend from British Honduras to Southern Nicaragua;these species are in great demand for building in thosecountries.

The Castilloa rubber tree is fairly abundant, andimportant as a source of rubber; and many attemptsare made to grow Pará rubber (Hevea brasiliensis)on big-scale plantations, some of which seem now tobe in very good shape.

Several palms—coconut (Cocos nucífera), corozo(Coroza) and others—are also abundant in many places,and promise a good future yield.

As most of the Central American forests have notyet been exploited on a large scale and the economicpossibilities are important, the time is ripe for suchexploitation under sound silvicultural practices.

At the Interamerican Institute of AgriculturalSciences, Turrialba, Costa Rica, under the able leader-ship of Dr. L. R. Hooldridge, a well-oriented movein that direction is in progress.

AGRICULTURE

In Central America subsistence crops, namely corn,beans, rice, manioc, are cultivated everywhere andgenerally consumed locally, although a surplus isfrequently sent to towns up country.

Besides these crops, other cash crops play an impor-tant role in the national economy of several of thesecountries. Specially important is coffee (Coffea arábiga),which is grown in many places and fetches high prices

for its excellent quality. Costa Rica, El Salvador andColombia export large quantities of coffee.

Bananas have frequently figured among the mostimportant exports of Central America, but diseasehas in the past almost wiped out the crop in manyplaces. The situation today points to a renewed interestin that culture, but its future is hard to prophesy.

Sugar-cane has some importance too, hoth for localconsumption and for export but this culture nowhereattains the place it holds in the West Indies.

Agricultural research has been carried out for manyyears by corporations like the United Fruit Company,and in more recent times almost every country hasestablished its own research and development centres.

A very important step in this direction was thecreation of the Interamerican Institute of AgriculturalScience, located at Turrialha, Costa Rica, which hascarried out an active and fruitful research and extensionprogramme, focused mainly on problems of the Carib-bean zone.

ANIMAL BREEDING

Although the humid tropics are theoretically favourablefor cattle-raising, because the climate provides food foranimals all the year round, there are important han-dicaps. To get good pastures, it is generally necessaryto clear the original forest, to seed grass and maintainit at great expense. Besides that, many parasites anddiseases peculiar to the humid tropics interfere withthe raising of local breeds, and in some places makeit almost impossible to introduce new and better ones.

None of the Central American or northern SouthAmerican countries bordering the Caribbean can beconsidered places of importance in animal breeding. Allof them raise numbers of animals, but mostly for locaiconsumption, and generally by very primitive methods.

In this context, it is interesting to note that, at theInteramerican Institute of Agricultural Sciences,Dr. Jorge de Alba has been working for several years,in an attempt to develop a cattle breed—starting fromlocally selected animals—of acceptable productionqualities, resistant to disease and adapted to conditionsfound in the Caribbean tropics.

FISHERIES

Favourable conditions for fishing are found in mostof Central America, but none of the countries therehas real importance in that field. D'Alarcao gives thefollowing figures of fishing products landed at differentplaces in 1951: Costa Rica, 2,500 tons; El Salvador,400 tons; Guatemala, 250 tons; Honduras, 100 tons;British Honduras, 100 tons; Nicaragua, 200 tons; andPanama, 900 tons.

The quantities reported are small and not all ofthem are taken from Caribbean waters. This, of course,is the case in El Salvador; and Costa Rica, which

occupies first place, obtains most of its catch withtuna from the Pacific.

Quite different is the situation in Colombia, whichhas started to develop its fisheries and reports a totalcatch of 16,000 tons in 1951; this figure is still low,but promises well for the future.

In regard to Venezuela, the situation is better, witha reported catch of 75,000 tons, and a well equippedindustry for freezing and packing fish, especially bonitoand tuna.

The fishing industry of Central America offers agreat field for development, but very little fundamentaland continuous research has been carried out. In 1952an Interamerican Fisheries Conference attended bymost of the Central American governments, as well asother American countries, was held at Lima, Peru,to discuss how to improve and promote the fisheriesof Central and South America. Unfortunately, littlehas come out of that gathering. Even the proposedtreaty signed there by the delegates has not yet beenratified by enough governments to bring it into force.

The situation in regard to nutrition in Central Americais in many respects similar to that in the West Indies.However, population density is not so great. OnlyEl Salvador, with 56 inhabitants per square kilometre,is experiencing some trouble in this respect.

It cannot of course, be said that nutrition in thearea is really good, and much is needed to improve it.A very promising step in that direction was the creationin Panama of the Institute of Nutrition of CentralAmerica, under the administration of the Pan AmericanSanitary Bureau. This research centre has been work-ing to evaluate and solve the nutrition problems of thearea and much may be hoped from it.

In regard to prevalent diseases, the situation issimilar to that mentioned in the case of the Antilles.In some places, like Costa Rica for instance, efficientcampaigns have been waged against parasitic problemsoí local importance, such as hook worm disease.

The Gorgas Institute for Medical Research, locatedat Panama, is a very interesting research centre ontropical diseases, and it ha6 accomplished very usefulwork. The Medical Department of the United FruitCompany, has also carried out good research in thearea, especially in regard to such important diseasesas malaria.

PANORAMIC VIEW OF THE CARIBBEANREGION

THE SITUATION

As may be seen from the list of references that follows—which is not intended to be a complete bibliography

but only a short list of important papers—the situationin the Caribbean zone in regard to basic research hasvery special characteristics. There is of course abundantand important material on almost every count, butmost of it is preliminary or fragmentary.

AH the countries included in this report have manycommon characteristics, arising from their geogra-phical situation in the Caribbean zone. But three ofthem—Mexico, Colombia and Venezuela—must beplaced in a special position, since only a small part oftheir territory may be included in the region underconsideration here. That is particularly true of Mexico,where the great bulk of the population, as well as themore important cities, are situated not only far fromthe Caribbean, but in the temperate zone.

AH of them are included under the general denomi-nation of "Latin America", which gives them certainuniform characteristics.

The common background is, of course, the racialmixture of native Indians and Spanish conquerors.They have the same official language and the sameprevalent religion. But there are interesting exceptions.For instance, Haiti, which occupies half Hispaniola,has a Negro population and talks a more or less modifiedFrench. Guadaloupe and Martinique have similarFrench influences. British Honduras, Jamaica, Trinidadand Tobago, also with a great proportion of Negroesin their territory, speak English and are under Britishrule. Puerto Rico, although keeping its Latin physiog-nomy and talking Spanish, is now one of the UnitedStates of America.

Most of these countries have a predominantly agricul-tural economy, that provides the basic foods consumedby their inhabitants. Some have also an importantcash crop for export of basic importance in the nation'seconomy; for example, sugar in Cuba and Puerto Rico;bananas in Guatemala and Honduras; coffee in ElSalvador and Costa Rica.

Economically, all may be grouped under the nowgenerally accepted term of "underdeveloped countries".But the meaning of such a denomination varies greatlyfrom one to the other, and so does the rhythm observedin each of them in developing the national economy.

None of them is an industrial country, of a significancein the international market. But there are all kinds ofdifferences in their industrial rank. Some are wholly non-industrial; others have quite significant light industries,and a few of them are now starting heavy industries.

Population problems vary in the area. In someplaces density is still low; in others population pressure,especially in view of an unfavourable environment, is amatter of urgency.

PROBLEMS

The basic problem in the Caribbean region is to obtaina good day-to-day outlook of the state of knowledgereached in the different fields of research.

Because of the "underdeveloped" stage of most ofthese countries, it is generally supposed that almost noresearch has been done. Nothing is farther from thetruth. In almost every country included in this surveymuch interesting research has been done in severalfields.

The difficulties of evaluating these accomplishmentsare twofold. Some of this research work, carried outby nationals of the countries, has been published inlocal journals—many of them with a very small circu-lation—and mostly in Spanish, which is not generallyconsidered a basic scientific language. Other work hasbeen carried out by foreign scientists, and publishedin their own languages—English, French or German—injournals abroad, which are not always easily available,or are overlooked, because references to Caribbeanproblems in such journals are only incidental.

Hence, the most important task, at the moment, isto assemble work already done. Then will follow theother more serious and complicated affair: to evaluatethe importance and reliability of each contribution.

With such information to hand, it should be possibleto pinpoint existing gaps and to plan ahead the researchnecessary in order to fill them.

The last—and perhaps the most difficult—step willbe to co-ordinate all this fragmentary research work,and to correlate each piece into a well integrated pano-ramic picture, as the final goal of any attempt tounderstand the basic research problems of a country

THE OUTLOOK

In the past, most of this basic research was carriedout in the temperate zone, and its aim was to knowand solve the problems peculiar to such areas.

Since the middle of last century various factors havecompelled attention to the tropics. First, the specta-cular development of some wholly or partly tropicalcountries, for instance India, Indonesia, Mexico orBrazil. Second, the new economic structure of the world,which attaches special importance, for industry every-where, to certain raw materials of the tropics—rubber,to mention only one. And, third, population pressurein the temperate zone, and the low density still preva-lent in many tropical regions, point to the potentialitiesof the latter for the world's future.

This situation has lent added emphasis to tropicalresearch in all its aspects. There are many scientificinstitutions in the temperate zone devoted to tropicalresearch; those in Europe are mostly concerned withproblems of the Old World, principally Asia and Africa;those in the United States of America focus ratherupon aspects related to the Western Hemisphere. Someof those institutions have done very fine work; andtheir publications are rich sources of information. But,although many special problems of the Caribbean havebeen investigated in such places, we are not referring

Rapport sur la région des Caraïbes

to them here. We prefer to centre our attention onthose which are located in the Caribbean countriesthemselves.

Recently the Pan-American Institute of Geographyand History conducted a wide survey of the state ofknowledge of natural resources in Latin America. Thereport, in five volumes (1953-54), offers interestinginformation about existing research centres—in suchfields—located in the Caribbean countries, as well assome of the basic work done in geography, geology,meteorology, climatology and both renewable and non-renewable resources. This report is an indispensablesource of information. It constitutes a very importantand overdue effort, but it was poorly carried out andis consequently of limited usefulness.

The Interamerican Institute of Agricultural Sciences,supported by the Organization of American States,and located at Turrialba, Costa Rica, is a very impor-tant research centre where Caribbean problems receivespecial attention. In addition, the Imperial Instituteof Tropical Agriculture in Trinidad has for many yearsdone very important work in the agricultural field.

The Institute of Nutrition of Central America, inPanama, administered by the Pan-American SanitaryBureau, is an interesting centre for the study of oneof the most pressing problems in all tropical America,namely nutrition.

The United Fruit Company, both in the medicaland agricultural field, has published many papers ofgreat interest. The School of Tropical Medicine in PuertoRico and the Institute of Public Health and TropicalDiseases in Mexico, are also important research centres.

Of course, there are in many of the Caribbean coun-tries local centres of general scope that tackle allkinds of problems, among them some of tropical nature.

In October 1955, the Mexican Institute of Natural

Renewable Resources sponsored a very interestingseries of round table discussions under the generalheading of "Problems of the Mexican Humid Tropics",in which were discussed—in relation to Mexico—thefollowing subjects: "Tropical Soils", "Tropical Forests","Tropical Agriculture", "Tropical Diseases" and "Eco-nomic Aspects in the Tropics." The volume publishedby the institute (1955) is now one of the best sourcesof information in the field.

The Mexican Institute of Natural Renewable Re-sources started a wide survey on "Natural Resourcesof South Eastern Mexico and their Utilization" in 1954.This survey covered the peninsula of Yucatan—mostly humid tropics—from all possible angles: place,resources and population. The survey was publishedin 1956 and is an important contribution to theknowledge of an extensive Mexican tropical region.Besides that, the work has a more fundamentalvalue, being one of the few attempts to treat in anintegrated fashion all the problems of a humid tropicalzone in the Western Hemisphere. While the particularresults and conclusions of this survey will be of localinterest, the organization of the work and the tech-niques developed, may, it is hoped, serve a more generalpurpose, with applications to other countries as well.

In conclusion, we may say that the general outlookfor the future of basic research in the humid tropicsof the Caribbean region is quite encouraging. Newcentres are being established or planned everywhere, andmore and more information is pouring out from them.

In our opinion the most important task ahead—andone of an international character—is to point clearlyand precisely to the more important problems yet tobe solved, and to plan a practical way to interchangeand co-ordinate results between the different countriesconcerned.

Rapport sur la région des Caraïbespar

le Dr Enrique Beltran

Résumé

Tous les pays dont il est question dans le présentrapport ont de nombreux traits communs, qu'ils doi-vent à leur situation géographique dans la zone desCaraïbes. Toutefois, trois de ces pays (le Mexique, laColombie et le Venezuela) doivent être mis à part,

étant donné qu'une petite portion seulement de leurterritoire appartient à la région considérée.

Ils ont évidemment un fonds commun, venant dumélange racial des Indiens autochtones et des conqué-rants espagnols; ils ont la même langue officielle et

la même religion prédominante. Il y a cependant desexceptions, d'un grand intérêt.

La plupart de ces pays ont une économie surtoutagricole, et c'est de l'agriculture qu'ils tirent les pro-duits alimentaires de base consommés par leurs habi-tants. Certains ont également des cultures de rapportorientées vers l'exportation, qui sont d'une importancecapitale pour l'économie nationale: par exemple,la canneà sucre à Cuba et à Porto Rico, la banane au Guatemalaet au Honduras, le café au Salvador et au Costa Rica.

Parce que la plupart de ces pays sont « sous-déve-loppés » on suppose généralement que rien, ou presquerien, n'a été fait en matière de recherche. Rien n'estplus loin de la réalité. Dans presque chacun des payssur lesquels porte cette enquête, de nombreuses recher-ches pleines d'intérêt ont été faites en divers domaines.Mais quelques-uns de ces travaux de recherche ontété publiés dans des revues locales — dont beaucoupn'ont qu'un tirage très restreint — et le plus souventen langue espagnole. Le reste, œuvre de savants étran-gers, a été publié dans leur propre langue (anglais,français ou allemand) dans des revues étrangèresqui ne sont pas toujours facilement accessibles.

A l'heure actuelle, la tâche la plus importante consistedonc à rassembler toutes les études qui ont déjà étéfaites. Une fois terminé ce travail préliminaire, on setrouvera devant un autre problème plus difficile et pluscomplexe, consistant à évaluer l'importance et l'exacti-tude de chacune de ces études.

Ayant en main ces renseignements, on pourra releverles lacunes qui subsistent et dresser le plan des recher-ches à faire pour les combler au mieux.

L'Institut panaméricain de géographie et d'histoirede Colombie, l'Institut interaméricain des sciencesagricoles du Costa Rica, l'Impérial Institute of TropicalAgriculture de la Trinité, l'Institut de nutrologie del'Amérique centrale au Panama, l'École de médecinetropicale du Porto Rico, l'Institut de la santé publiqueet des maladies tropicales du Mexique, ainsi que l'Insti-tuto Mexicano de Recursos Naturales Renovables deMexico sont des centres de recherche très importants.

Pour conclure, on peut dire que les perspectivesgénérales d'avenir qui s'offrent aux recherches fonda-mentales dans la zone tropicale humide de la régiondes Caraïbes sont très encourageantes. Partout descentres nouveaux s'installent ou sont en projet.

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295. WOODWORTH, R. H. "Economic plants of St. John U.S.Virgin Islands", Bot. Mus. Leafl. Harvard Univ. 1943,no. 11, p. 29-56.

296. YUNCKER, T. G. "A contribution to the flora of Hon-duras", Field Mus. Nat. Hist, pubi, Bot. Ser.-1938,no. 17, p. 287.

297. . "The vegetation of Honduras", Plants and PlantsScience in Latin America. 1945, p. 55-56, ed. F. Veerdorn.

Report on the Humid Regionsof South Asia

byDr. E. K. Janaki Ammal,

Central Botanical Laboratory, Botanical Survey of India

INTRODUCTION

The "humid tropics" represent the highest stage ofnatural vegetation in the world. They are remnants ofa vegetation that extended over a great part of theearth during earlier geological periods prior to therise of the Himalayas.

Three separate rain forest types are today found inthree different areas of the world: the rain forests ofCentral and South America, the African rain forests,and the Indo-Malayan rain forests. The study of theseforests is important, so as to ascertain what part theyplay in the general climate and other aspects of thecountry and how they may best be utilized and aunified policy for all humid regions of the world under-taken. We are chiefly concerned with the forests ofSouth Asia, which include India, Pakistan, Burma andCeylon and form part of the Great Indo-Malayan RainForest.

The emphasis on family values in Asia producesmore people than the natural resources can providefor. The continent has thus become denuded of herforests and the rich top soil of her earth has been washedinto the seas. The problem of feeding Asian countriesis becoming increasingly difficult. On an average,40,000 children are being born in India every hour ofthe day. The death rate is also high but, none the less,11 million are added annually to a population of360 million, the population according to 1951 census.This is a modest estimate and any change in the deathrate will increase the population, though floods andfamines may swing the pendulum the other way.

Millions upon millions of Asia's trees have beendestroyed never to be replaced. Prolific breeding andwant of sufficient food have resulted in once woodedlands being turned into barren lands.

The impact of this terrific rate of increase in popu-lation on the humid forests has been tremendous asmore and more land comes under the plough andmore and more forests are being cut down for timber

and firewood. The Grow-More-Food Campaign of 1948in India has done incalculable damage to forests,especially those on the Nilgiris and in Assam. This isreflected in the almost yearly floods experienced in theplains.

Apart from producing the food necessary to keepthe population in a healthy state, food has to be pro-vided for India's large bovine population, the principalfunction of which seems to be the production of dungto be used as fuel. Space is also required for increasein the production of raw materials needed for export.

A just balance between land utilized for cash cropsand internal consumption has to be arrived at. In thepast, this problem was not studied and land utilizationwas controlled by the needs of industry and the whimsof the foreign market. The lack of planned researchon problems relating to tropical ecology was pointedout by Bor in 1947.

CLASSIFICATION OF TROPICAL VEGETATION

Moisture and temperature are the two great factorsthat determine the type of forests in the tropics.Schimper [21]1 classified vegetation types of the tropicsin a series with decreasingly favourable moisture condi-tions as follows: (1) rain forest; (2) monsoon forest;(3) savannah; (4) thorn; (5) tropical grass; (6) tropicaldesert.

India, Pakistan, Burma and Ceylon have an extre-mely wide range of moisture conditions from virtuallyrainless tracts in West Pakistan to nearly 500 inchesin Assam. A rainfall exceeding 80 inches usually resultsin rain forest. Precipitation over 100 inches is metin the following parts of the country:1. Western Ghats—from Bombay along the whole

length of the Western Ghats, Coorg, Wynaad,Mysore, Nilambur, Cochin, Palghat to Travancoreand Tinnevelly.

1. The figures in brackets refer to the bibliography on page 53.

66* 68' 72" 76° 8o° 64' 92* 96°

68» 92"

Tropical wet evergreen

Tropical semi-evergreen

Tropical moist deciduous

Tropical moist deciduous (sal)

Tropical dry deciduous

Tropical thorn forest

Tropical dry evergreen

Sud tropical wet forest

I Sud tropical pine

I.L+++++J Sud tropical

FIG. 6. Burma, India, Pakistan. Distribution of climatic types.

. A A/J Moist temp

r ^ Q 0 ^ Ottemperate

^ ^ Alpine

Report on the humid regions of South Asia

2. Burma, South Tennassarim.3. Hill slopes of the Andamans.4. South-west Ceylon.5. Assam and North Bengal.The whole rainfall occurs during the monsoon. Therainy season varies in duration, with a general increasefrom north-west to east and south-east. Upper Assamand Lower Tennassarim experience the shortest dryperiod and the north-west the longest. During themonsoon, the south-east of the peninsula of India,i.e., the Carnatic, gets little rain from the south-westmonsoon which blows from June to September. Mostof the rain here falls from the retreating or north-east monsoon in October and November. This hasresulted in the differentiation of a special type of vege-tation not met anywhere else in the country and charac-teristic also of north and east Ceylon. The lengtheningof the moist season where the effect of both rainy periodsis felt also influences the vegetation as in Nilgiris andparts of Travancore and Ceylon.

One factor brought out by the examination of Indianflora is that it is the result of a changing factor, i.e.,of increasing periods of dryness in a once universallyhumid forest type. Given the full force of the monsoonand a short dry period, all forests in India are capableof rising to the climax, the rain forests. This musthave happened repeatedly in the course of the lastglacial periods in Europe when peninsular India wasundergoing a pluvial age.

Latitude exerts very little difference on forest florain South Asia. Tropical forests are also found alongthe coast especially in the deltaic regions of the greatrivers, Irrawaddy, Ganges, Mahanadi, and the beachesin the Andamans, Tennassarim and Arakan, andTravancore-Cochin backwaters.

According to Stebbing [22], India may be dividedinto four climatic zones, which have a marked influenceon her vegetation:1. The dry zone—average rainfall 15-30 inches: this

zone comprises the large oval plateau-like tract inwhich the Godavari, Krishna, and Cauvery havetheir sources and extends from Nasik in BombayPresidency to Bangalore with an average widthof 200-250 miles.

2. Intermediate zone—average rainfall 30-50 inches:a narrow belt to the west of the dry zones.

3. Moist zone—average 50-75 inches: seaboard of theS. Peninsula.

4. Wet zone—average rainfall 75 inches: the remainingpart of West Ghats and Assam.

Stebbing [22] classifies the forests of India as follows:(1) evergreen forest zone, and (2) deciduous forest zone(dependent on or due to rainfall); (3) dry (paucity ofrain); (4) alpine (due to elevation); (5) riparian (over-flow of rivers); (6) tidal (subject to tidal influence);(7) zone without forests (due to absence of rain).

Kceppen [10] makes an advance in the classificationof forests by combining temperature, rainfall and the

season when the rain falls. He recognizes 11 climaticregions:

Chief Easternexamples

1. Af, tropical rain forest ¡ „ . . - , . _/ Tropical rainy Malaya, Cen-

climates trai Indiaclimate

2. Aw, savannah climate3. BS, steppe climate4. BW, desert climate5. Cw, warm winter—dry

climate6. Cs, warm summer—-

dry climate7. Cf, moist-temperate

climate8. Dw, winter—dry cold

climate9. Df, winter—damp cold

climate10. ET, tundra climate11. EF, eternal forest cli-

f Dry climatesEast Punjab,Sind

Upper IndiaWarm temperate (Mediterra-rainy climates nean)

Nilgiris

Boral or snow-forest climates

Snow climate

Western Sibe-riaEastern Sibe-riaNorthern Si-beria(Greenland)

According to Champion, the tropical forests are classi-fied as: (1) wet evergreen forest (rain forests entirelyevergreen); (2) semi-evergreen (evergreen predominantbut also deciduous); (3) moist deciduous (dominantdeciduous—lower storeys evergreen); (4) dry deciduous(entirely deciduous, top canopy rarely 80 per cent);(5) thorn forests (deciduous with low thorny trees);(6) dry evergreen (hard-leaved evergreen trees butusually low).

Champion's classification has provided a good work-ing plan for initiating more detailed analysis. It isbased on the relative proportion of two factors, ever-greenness and deciduousness, which are dependent ontemperature, moisture and period of dryness.

A far more complete classification of tropical forestswill be arrived at when forests are also examined fromclimatic, ecological, botanical and genetical aspects.

THE COMPOSITION OF THE FLORA OF INDIA

(SOUTH ASIA), CEYLON

The total number of species of the flora of the worldis something like 200,000 species distributed in about12,500 to 15,000 genera, about one-fifth of these plantsbeing monocotyledons. The Indian sub-continent has21,000 species, which is more than one-tenth of thetotal number of species in the world. Brazil is the onlyother country with a larger number of species thanIndia. Yet, with all this diversity, India is, comparedwith China, Australia and South Africa, very poor inendemic genera. There is hardly one natural order ofplants that is peculiar to India.

This can be explained when we analyse the flora ofIndia and its constituents and trace back its originsand examine it as part of the flora of the wholeworld.

The flora of the sub-continent and Ceylon is composed

FIG. 7. Burma, India, Pakistan. Average annual rainfall.

A R A B I A N

mainly of what is termed the Indo-Malayan type.This forms part of the perennial humid regions of Indiain the Upper Assam Valley, Khasia Mountains, Brah-maputra Valley, Malabar Coast and Ceylon.

Apart from this, there is an African element confinedto western peninsular India. A Chinese and Japaneseelement occurs in the Temperate Himalayas up toNepal, and a European element, which mixes with aSiberian type, chiefly confined to the Western Hima-layas.

The flora of Ceylon is similar to that of South India,but Ceylon has also many species which are endemicto the Island.

GENERAL CHARACTERISTICS OF TROPICAL RAINFORESTS

A tropical rain forest is composed of a large numberof dominants and presents a physiognomy which isvery characteristic. Rain forest trees have straight tall

trunks with few branches; they are buttressed at theirbases and have smooth bark, leathery green leaves,with entire margin and drip points. Flowers are generallyinconspicuous, being greenish or yellowish, a charac-teristic of primitive families. Thus the rain forest,which was the dominant flora of the Tertiary, may beconsidered as the starting point in the evolution offlowering plant floras.

The forest is composed of a number of tiers, three orfour or five, of which the highest is often over 150 feetor more. Generally, different species represent differenttiers, each of which is a unit composed of a set ofgenera. One way of studying such a flora is to accepteach terrace pattern as a biological unit and study itin terms of its environment, i.e., the other terraces andthe soil on which it grows.

Woody lianes and climbing palms form a networkbetween the tiers, while shrubs form the undergrowthbelow them. Herbs, which may include seedlings oftrees, compose the lowest strata. Epiphytes are verynumerous.

One of the peculiarities of seedlings on the groundis that they can remain stunted for many years, butwhen given a chance—as by the death of a tree—theycan shoot up very rapidly. This peculiarity is probablylinked with the great competition in the root systems;the same principle applies to the artificial productionof "nana" varieties in Japanese horticulture by cuttingaway roots of pot plants.

More experimental work on the living flora of tropicalrain forests is urgent for the understanding of thebehaviour of plants on the face of the earth. As humidforests are fast changing their original character atthe hands of man, their study should command toppriority from the botanists of the world.

FLORISTIC COMPOSITION OF HUMID FORESTS OFSOUTH ASIA

As a rule, tropical evergreen forests found on meta-morphic rocks are richest in species while those onsandstone and other sedimentary rocks are poorestin species.

The following is an analysis of the floristic compo-sition of humid forests of India, Pakistan, Burma andCeylon after Stebbing [22].

Humid Forests Distribution

West Coast Region of India. Konkan, Cañara, Malabar,and Travancore extending over to western scarps ofthe mountains, Coorg, the Nilgiris, Anaimalais, Cochinand the Travancore Hills. Trees of this region belongto the following families: anacardiaceae, anonaceae,dipterocarpeae, guttiferae, myrtaceae, rubiaceae, lauraceae,euphorbiaceae.

In parts, dry areas exist with growth like the deci-duous forests of Central India and with a good dealof teak. The greater part consists of hill forests; the

lower hill slopes abound in species of the followinggenera: dalbergia, xylia, artocarpus, pterocarpus, larger-stroemia, terminalia, vateria, canarium, cullenia, poly-althia, mesua.

Higher up and especially in the hill regions of theNilgiris, Anaimalais, Pulneys and Travancore moun-tains, these evergreen forests merge into what areknown as the "sholas"; the principal vegetation regionis Eugenia: michelia, ilex, hydnocarpus, elaeocarpus,ternstroemia, gordonia, symplocos, rhododendrons, laurels,with undergrowth of strobilanthes and tree ferns.

In this region teak is the chief export tree, followedby blackwood (dalbergia latifolia). In the coastal tractthe talipot palm is conspicuous and in the Ghat regionare found bentinchia and arenga wightii with manycanes and bamboos, such as teinostachyum wightii,oxytenanthera thwaitesii, and species of ochlandra andarundinaria wightiana.

The Burmese Region. The Burmese region of evergreenscomprises the coast and western mountain slopes ofthe Mergui, Tavoy, Amherst, Kyaukpyu and Arakandistricts, broadening and contracting according to theformation of the mountain chains.

The variety of these forests is very great and theheight of the trees forming the upper canopy rangesfrom 150 to 200 feet, the tallest being: dipterocarpusturbinatus and D. alatus, sterculia spingerà, S. faetida,and S. campanulata, tetrameles mudiflora, parkia leio-phylla, acrocarpus fraxinifolius, albissia lebbek, A. stipu-lata, xylia dolabriformis.

The above are leaf-shedding trees which tower abovethe mass of less lofty evergreens, namely: mesua ferrea,mitrephora vandaeflora, bursera serrata, kurrimia robusta,stereospermum fimbriatum, vitex peduncularis, adenan-thera pavonina, cedrela toona, lagerstroemia calyculata,largerstroemia villosa, and L. tomentosa, mangìfera indica,treivia nudiflora. A still lower storey is formed by :pterospermum, garcinia, xanthochymus, cinnamomum:tetranthera and others. Climbing palms and bamboosare also numerous like: calamus latifolius and C. longi-setus. Palms and screw-pines are found dispersed.

The Carnatic Region of India. Here there is a differentclass of forests in good condition, presenting densethickets of close-growing trees, though few of any greatsize. Most of them are valuable hardwoods. Carelesscutting reduces them to a condition of thorny scrub.The area begins with the Mahanadi and goes downthe whole of the eastern coast. The best forests are inNellore, Cuddapah, and North Arcot. Chief amongstthe trees are species of: mimusops, diospyros, pteros-permum, eugenia, memecylon, pleurostylia. In badcondition, there are thorny shrubs such as randia,canthium, dichrostachys. Zizyphus are in good order.

Sub-Himalayan Region. The belt of country borderingon the spurs of the eastern Sub-Himalayas. The number

80°"3 io1

AVERAGE RAINFALLIN INC M CS

H IÎS-IMfá¡2 100-123^ 3 7S- «0

, l j 9O- 75. .1 a» - »

80° 82°

FIG. 8. Ceylon. Distribution of annual average precipitation.

of species is very great: schima wallichii, terminaliatomentosa and T. myriocarpa, artocarpus chaplasha,dnnamomum glanduliferum, echinocarpus sterculiaceus,bombax malabaricum. dillenia indica, eugenia formosa,pterospermum acerifolium. On the low hills occur:magnolia, michelia champaca, duabanga champaca,duabanga sonneratioides. On still higher elevationsoccur: castanopsis indica, alnus nepalensis, bucklandiapopulnea.

Ground with ferns, climbers and inferior shrubs,partly on the hills, and a dense growth of bamboo(dendrocalamus), and also wallichia disticha and caryotawens, are conspicuous.

The Deciduous Forest Zone of Peninsular India. Dividedinto Central India deciduous zone,and Burma deciduous.

The Central India deciduous zone is the forest typeof India. It extends from the southern slope of PunjabHimalaya, eastwards up the valley of Assam and southto Cape Comorin. It varies in character and species indifferent parts but its general character and growthremain the same. Some species are found universally,

such as: terminalia tomentosa, T. arjuna, T. belerica,T. chebula. Others more local are: lagerstroemia parvi-flora, butea frondosa, bombax.

Anogeissus does not extend to North Bengal, ptero-carpus marsupium and bassia latifolia do not cross theGanges. Dillenia and careya are rare in Kistna.

This deciduous forest covers the plain country ofthe North-Western Provinces, the Terai, the Duarsand Chota Nagpur, the hill tracts of Orissa and theCircars, the Central Provinces, Bihar, Guzerat, andCentral India, Hyderabad and the East Mahratta coun-try, the Bellary, Cuddapah and Mysore Hills, the hillsof Coimbatore and Salem, the eastern slopes of theNilgiris, Palnis and parts of Tinnevelly. It consists ofseveral sub-regions of: (a) sal (shorea robusta) whichfollows the foot of the Himalayas from the Sulleg tothe Borelli and extends to the Godavari in the Circarsand to Nagpur in the Central Provinces ; (b) the regionof ironwood (xylia dolabriformis) in the forests of theCircars from the Mahanadi to the Kistna extendingwestwards and the Chanda district and Hyderabad;(c) the region of teak (tectona grandis) ; (d) the regionof red sanders (pterocarpus santalinus) on the hills ofCuddapah and North Arcot; (e) the region of sandal-wood (santalum album) on the hills of Bellary, Coim-batore and Salem and the N. Nilgiris.

Other trees of the forest are terminalias, lagerstroemiaparviflora, anogeissus latifolia, dillenia indica, eugeniajambolana, ougeinia dalbergioides, soymida fabrifuga,chloroxylon swietenia, pterocarpus marsupium, diospyrosmelanoxylon, bassia latifolia, dalbergias, albizzias, bom-bax, wrightia, caruga, bursera, holarrhena, bamboo(dendrocalamus strictus), dalbergia sissoo, acacia catechu,aeucophloea on sandy soil.

Forming part of the region is the black cotton soilwith acacia arabica, albizzia lebbek, melia indica, poin-ciana elata, balanites roxburghii.

Ceylon. Three types of evergreen forests are met within Ceylon, which correspond to the type seen in SouthIndia: (a) tropical wet evergreen or southern tropicalwet forests; (b) tropical dry evergreen or monsoonforest in the north which gets its rain from the recedingnorth-east monsoon; (c) the sub-tropical wet ever-green montane forest which is similar to that of theNilgiris. The distribution of these forests is dependenton altitude and rainfall.

The following species are found in the southern rainforests which in many respects are similar to those ofthe west coast of India. The canopy is composed ofspecies of depterocarpaceae, D. zeylanicus, D. lispidus,also palaquuim, pygeum and mangifera. Messua ferrea,durio zeylanica and species of myristica and calophyllummake up the main dominant layer, while dillenia,wormia, semecarpus and othe- smaller evergreen treesmake up the sub-canopy. Memecylon and polyaltheaacuminata form the shrub layer below. For more detailedstudies, consult de Rosayro [16-18].

THE RELATION BETWEEN SOIL AND VEGETATION

IN TROPICAL FORESTS

According to Schimper [21] the most important aspectof soil is the efficiency with which it acts as an inter-mediary in retaining and transferring the rainfall orsubsoil water to the tree growth. Thus, effective depthand texture are most important.

However, the interaction between soils and vegeta-tion is a very close one. Soils undergo a process ofdevelopment similar to that of the vegetation theysupport. The geological materials forming the bedrockare more passive than active in soil formation. Fromthe growth of vegetation and the accumulation anddisorganization of organic substance helped by micro-organisms, new chemical substances are found. Intemperate climates, when the rainfall is greater thanevaporation, an acid soil results. Soils of tropical rainforests have certain common characteristics. They aregenerally loamy or clayey red or yellow, rich in aluminaand poor in silica.

In North Bengal, the semi-evergreen forests of newriver alluvium are first colonized by acacia catechu,a typical tree of thorn forest ; this thorn forest progressesthrough a dry mixed deciduous stage to a moist deci-duous and finally to a more or less evergreen climaxas a result of changes in the soil brought about byvegetation.

Absence of sal on the west side of the Indian penin-sula is connected with its liking for siliceous soil. Thereis a changeover from sal to teak in Central India; teaklikes alluvium. Sal grows best on metamorphic rocks.

Topography is important chiefly in the carrying awayof soil when vegetation is not dense; hence the dangerof too much felling of trees on mountain slopes.

Mapping of soils is an urgent need in the study ofthe forests of South Asia. The action of leaching byrain on different types of rocks is little understood.Latérite is formed from both igneous and metamor-phic—and even sedimentary—rocks and more detailedstudy of latérite from different parts of the humidforests is urgently needed.

THE ETHNOLOGY OK HUMID FORESTS

It appears that the emergence of man took place ina West-East Himalayan belt ranging from equatorialAfrica to Malaya; that is, in the humid forests of theOld World, in which happened to be concentrated, atthe closing of the Tertiary period, the most advancedrepresentatives of the Tertiary primates, the pongideae.As with plants, this mutation belt was ruptured inthe middle by the severance of India from Africa andwe have now evidence of two centres of origin of man,one in Africa and one in Indo-Malaya.

Ever since this mutation took place, the humidforests have been under the hand of an animal, Homosapiens, who has been steadily increasing his power

to change his environment. But this power came toman when he himself ventured to move out of theenvironment of trees to that of open spaces which hehimself had created, by the burning of forests. Thisenabled him to live in groups whereby he was able toward off the attacks of wild animals and develop pri-mitive community life. Later developments of manare connected with his life outside the forests, alongthe banks of rivers or in open spaces where he herdedand domesticated animals. Here he probably dependedon caves for his dwelling.

Today the humid forests in all parts of the worldare still inhabited by the most primitive of aborigines,some of whom are still in the Neolithic age. Amongstthese tribes may be included the Nigritos of the Anda-mans, the Kadars of the Anaimalais, the PannyarKuruchiars of Wynaad and the Veddhas of Ceylon wholive by food gathering aad use wooden digging sticksto gather roots. In general, these people do not upsetthe biological ecology of the forests they occupy. Asa food gatherer, man is here part of the biotic commu-nity of forests. It is true that he digs for roots, but thedamage done in humid luxurious forests is not great.It is true he hunts, but he hunts for his living and notfor export. His family is small because he does notreproduce as prolifically as urban dwellers, the timeof nursing being prolonged until children are able todigest roots and meat.

It is only when tribes take to cultivation or pastorallife that the biological balance is upset. "Jhumming"or shifting cultivation as followed by primitive tribesin Assam and the Irulas of Western Ghats, is responsiblefor the changeover from the climax. Selective destruc-tion of certain trees needed in tribal economy, ascaryota urens for starch and digging stick and artocarpushirsutus for dugouts and canoes, may cause somechange in the flora. There is probably a unity or asimilarity in the tribes that inhabit tropical humidforests which has escaped the notice of anthropologists.It is to be hoped that studies on a world scale of primi-tive man in humid tropical forests and his relationshipswith the fauna and flora of tropical forests will be oneof the items undertaken in future as part of the ecolo-gical studies of humid forests.

THE MODIFICATION

CIVILIZED MAN

OF HUMID FORESTS BY

Man's role in modifying the biotic composition of humidforests may be considered in two groups of processes.First, there are the effects induced by pioneer culturein areas peripheral to the main population. This iscaused by destruction of trees for timber, firewood orcharcoal. It is peripheral because man has not hadtime to penetrate into the entire region of the forests.Pioneer exploitation is not concerned with whether asecond crop would be forthcoming. All cuttable treesfall victims to the axe of firewood or charcoal gatherers

from surrounding urban areas. The second is the effecton land of its intensive use for cultivation by man.This follows the pioneer effect.

Selective felling is practised by civilized man forthe utilization of only a few species for special uses,as for veneers.

The intensive utilization of trees in sub-peripheralareas is generally accompanied by the introduction ofgrazing animals. Driving cattle into forests is quite acustom in Malabar. Many may be killed by leopards,panthers or tigers. Elephants in captivity are alsoallowed to graze in forests adjoining their camps. Thusa pressure is exerted from without to within. The sameapplies to plantation, rubber, tea and coffee in sholas.These bring about a shift in species composition bothin number and quality. The component species change.Regeneration is dependent on the rate of movementof distribution of seeds.

More important is the breaking up of the canopywhich changes the microflora of the inner forest. Themicroclimate changes the intensity in evaporation andthe balance or stability of the forests changes. Theinvasion of open space in forests by such plants as Ian-tana can completely alter the physiognomy of a forest.

AGRICULTURE IN HUMID FORESTS

The whole of India, Pakistan and Ceylon is part of themonsoon region of the world and the vegetation isvery much influenced by the amount of rainfall received.This again reflects on the agricultural economy of thepeople occupying these regions, the highest vegetationclimax being tropical evergreen forest. The evergreenforests consist of a bewildering number of species oftall trees and the vegetation forms three storeys witha large number of woody climbers in between whichmake the forests practically impenetrable to man.Semi-evergreen forests adjacent to the evergreen onesare of lesser density, and man has a better chance ofconquest over the vegetation here, and food gatherersare found living in little groups in open places. Pri-mitive agriculture in the tropics must have evolvedin these regions. "Jhumming" or shifting cultivationby burning and scattering of seeds in the ash is theonly type of agriculture practised.

The most highly evolved type of "jhumming" isseen in Assam where a regular rotation of clearance offorests takes place, once every eight years, so thatsufficient time is given for regeneration of the forest,which is quick. However, owing to pressure of popula-tion, this rotation has not been adhered to in recentyears. The effects of shifting cultivation are mostconspicuous on the hills in the north-east of India,between Bengal, Assam and Burma. The Forest Depart-ment of India is at present making use of tribal peoplefor growing and protecting young trees together withtheir crops, so that when the land is set free fromshifting cultivation, a plantation of trees is in the mak-

ing. It is apparent that this continual cutting willproduce considerable change in the flora of these parts,for the flora that comes up after clearance is never thesame as the one that has been destroyed. According toChampion (1935) shifting cultivation prevents thedevelopment of the climatic climax.

The practice of declaring part of forests as sacredhas done a great deal to keep the vegetation unchangedin Assam. These sacred forests belong to local chiefsor tribal village communities and represent what maybe called nature's primeval forests. Aboriginals didnot dare to cut the trees for fear of disturbing sylvanspirits. Hence, we have here rich stores of botanicalcollections which have become extinct in other partsof Assam. Sacred forests are also a feature of Malabar,where they are known as kavus. They serve as sanc-tuary for snakes and wild life and often become thenucleus of sylvan temples at a later stage.

T H E 'PARAMBA CULTIVATION

Shifting cultivation is generally practised in hilly tractswhere the rainfall is fairly high. As a more settled lifedevelops, an equilibrium is reached between man andhis environment. This is best seen in Malabar where amixed cultivation follows "jhumming". Clearance isonly partial and useful trees are preserved either fortimber or firewood or for growing of pepper and othervines. Amongst trees kept uncut are species of arto-carous and the wild mango, nutmeg, strychnos andcycas. Ginger, turmeric, yams, banana, and tapiocaare grown between trees which are pruned annually.Garden vegetables are also grown round the houses.Low lands are set aside for rice cultivation.

The paramba form of cultivation, characteristic ofthe west coast of India and Ceylon, does not upsetthe ecological balance of the natural vegetation and avariety of useful plants are grown simultaneously allthe year round. Thus each paramba is a self-supportingeconomic unit. This type of plantation comes nearestto nature and has been practised by man in humidregions of the world from time immemorial. The demandof cash crops for export, such as rubber, pepper, tea,coffee, bananas, which are grown in homogeneousblocks by both foreign and indigenous planters, hasresulted in changing cultivation from the parambatype to the plantation type. It has resulted in thecutting down of valuable trees and in changing thewhole physiognomy of the landscape. The growing oftapioca, almost on a plantation basis in the slopes ofthe Anaimalais, and of potatoes on the Nilgiris, hasresulted in erosion on a scale never before seen in thehistory of these parts of South India.

ECONOMIC PRODUCTS OF HUMID FORESTS

Besides the valuable timber that tropical forests yield,if properly managed, humid forests can be a rich source

of revenue to the State from the utilization of minorproducts found in the forest—bamboos, fibres, distilla-tion products, honey, lac, grasses, tannin barks anddrug plants.

Owing to the difficulty of gathering these products,the custom is to auction out forests to contractors whoemploy local aboriginals for labour to collect the pro-duce. This contact with civilization has already upsetthe life of the primitive, who has given up his old habitsof food gathering and taken to a more "civilized"way of life. The forests are ruthlessly cut down by thecontractor, who takes all he wants. This should bestopped by the Forest Department.

The minor natural resources of forests need as muchprotection as the trees and the number of officersengaged in this phase of forestry should be greatlyincreased. This would give employment to many youngbotanists who would thus become familiar with tro-pical forests and their ecology. Each type of "minor"forest produce needs special handling and study; forexample, there should be a special officer in chargeof the rattans of Indian forests. India is importingmany lakhs' worth of canes from Malaya. It is possiblethat the same or better varieties may be gatheredfrom the west Coast and Andaman forests.

The humid forests are also rich in medicinal plants,such as rauwolfia, and they should be explored fornew drug plants. In particular, we need to know moreabout the uses of plants by aboriginal tribes. We maythus be able to discover new economic plants whichcould be introduced into cultivation for large-scaleproduction and export—civilization is indebted toprimitive man for the cinchona, rubber, cocaine, cocoathat he is cultivating today. These are all productsof humid forests.

THE FAUNA OF HUMID FORESTS OF SOUTHASIA

The humid forest is the true home of big game. Theelephant (elephas indicus) once roamed throughout theforests of India, Pakistan, Burma, and Ceylon, evenin places like Agra in the Gangetic plain. Today itis chiefly found in the Terai from Bhutan to DehraDun, the forests of the west coast and the Anaimalaisand Shevorays of South India, in Ceylon and in Burma.The elephant of Ceylon is more closely related to theSumatran species and by some zoologists is placedunder it as elephas sumatranus. It differs from the Indianone in not having tusks. The elephants of India varyin size, those of hilly regions being slimmer and withlong legs to enable them to move faster.

The rhinoceros is found in Assam and the Sunderbansin India. The smaller, one-horned rhinoceros, R. son-daicus, inhabits the Sunderbans and parts of Pakistanwhile the great one-horned rhino is found only in theAssam Valley. The rhinoceros of Malaysia, R. suma-trensisis, the Asiatic two-horned rhino, is rarely met

in Assam. From Assam it ranges through the Malayapeninsula, Sumatra to Borneo. The rhinoceros has beenkilled ruthlessly for its horn which is considered medi-cinal, and its hide, which was once used for shields andsword handles in India.

The bison (garaeus gauras) which once roamed theforests of India has been ruthlessly slaughtered, sothat the herds have greatly dwindled in number.

The great cats of the humid forests are the tiger(felis tigris),felis bengalensis, the leopard cat, the leopardand the panther (felis pardus) and F. nebulosa, theclouded leopard of Assam. The lynx and the junglecat are also found in Ceylon and Burma besides India.These are all destructive to game, in which the jungleused to abound.

Among the deer family, the sambar rusa aristotetitis,the spotted deer axis maculata are the most common.

The wild pig sus indicus is found in all forests.Many species and genera of monkeys are found in

India, Burma and Ceylon. Owing to the semi-religiousattitude, the monkeys of India have increased innumbers and are now found in cities and have becomeveritable pests.

Some of the states of India like Assam, Travancoreand Mysore have wild life sanctuaries. These have tobe increased in number in regions where wild life isdwindling.

Large wild animals are absent from the Andamansowing to the island's long separation from the main-land. The only mammal there is a small pig which iskilled by the aboriginals for food. Even the monkey,which is so common in India, is not found in the Anda-mans. Rodents are quite common, the chief being ratsand bats.

THE FUTURE PROGRAMME FOR THE STUDY OF

HUMID FORESTS OF SOUTH ASIA

The future of the humid forests of South Asia willdepend on the interest taken not only by the botanistsof these regions but also by world organizations ofbotanists.

One of the first duties of every botanist is to seethat not a single species occurring in his part of theworld becomes extinct, as a result of careless treat-ment by man or animals.

The idea of sacred forests which kept rare speciesof plants alive in Asia for centuries should be takenup now in a more scientific way and protected areasdeclared as plant sanctuaries in different parts o£South Asia.

A uniform method of studying humid forests shouldbe evolved for South Asia as part of a world programmeso that forests in different parts may be examinedfrom the same angle.

Cytological studies leading to an understanding of thegenetical evolution of the floras of humid forests shouldbe made side by side with ecological and systematic

studies. An international bureau for chromosomestudies and exchange of slides and materials should becreated.

Ecological studies should include the study of theinterrelationships of fauna and flora in humid forests.

Ethno-botanical studies of aboriginals inhabitinghumid forests should be encouraged.

Vegetation maps of 1 : 10,000,000 scale showing theprincipal types of plant associations met with in SouthAsia should be prepared. Details of the uniform methodsof mapping will have to be taken up by an internationalcommittee.

As a complement to vegetation maps, aerial photo-graphs of the forests of South Asia should be made.

Rapport sur les régions humides du sud de l'Asiepar

le DT E. K. Janaki Ammal

Résumé

Les tropiques humides présentent le plus completdéveloppement de la végétation naturelle du monde.Il s'agit des restes d'une flore qui couvrait une grandepartie du globe au cours de périodes géologiques reculées,antérieures à la surrection de la chaîne himalayenne.

Aujourd'hui, on rencontre trois types distincts deforêts ombrophiles, correspondant à trois zones diffé-rentes du globe : Io les forêts ombrophiles de l'Amériquecentrale et de l'Amérique du Sud; 2° les forêts onxbro-philes africaines; 3° celles de l'Inde et de la Malaisie.

Le continent indien possède 21 000 espèces, soit plusdu dixième du nombre total d'espèces du globe. LeBrésil est le seul pays qui possède d'avantage d'espècesque l'Inde. Et cependant, malgré cette diversité, l'Inde,comparée à la Chine, à l'Australie, à l'Afrique du Sud,est très pauvre en genres indigènes. La flore de Ceylanest semblable à celle du sud de l'Inde, mais elle com-prend aussi beaucoup d'espèces qui sont indigènes.

Il est urgent que l'on procède à la cartographie dessols pour l'étude des forêts du sud de l'Asie. On saitpeu de choses sur le lessivage provoqué par la pluiesur divers types de roches mères. La latérite se forme

sur des roches volcaniques aussi bien que métamor-phiques, voire même sédimentaires. Il est urgent quel'on étudie plus en détail la latérite dans les différenteszones des forêts humides.

Aujourd'hui les forêts humides, dans toutes les partiesdu monde, sont encore habitées par les aborigènes lesplus primitifs. Certains en sont encore au stade néoli-thique. Parmi ces tribus, on peut ranger les Negritosdes Andamans, les Kadars des Anamalais, les PannyarsKuruchiars de Wynaad. et les Veddhas de Ceylan, quivivent de cueillette et utilisent des bâtons pour fouillerle sol et en extraire les racines. En général ces popula-tions ne bouleversent pas le milieu biologique des forêtsqu'elles occupent. C'est seulement lorsque les tribuss'adonnent à la culture ou à la vie pastorale que l'équi-libre biologique est bouleversé.

Des études, à l'échelle mondiale, sur l'homme pri-mitif dans les forêts tropicales humides, ainsi que surses relations avec la faune et la flore des forêts tropi-cales, devront être entreprises, à l'avenir, du pointde vue écologique, sur les forêts humides.

1. BHARUCHA, F. R. "Vegetation cartography*', Indian For. 3.1952, vol. 78, p. 305-309.

2. BOB, N. L. "A sketch of the vegetation of the Aka Hills 4.Assam; a syn-ecological study", Indian For. Ree., 1938(N.S.) Bot., vol. I, no. 4.

BOR, N. L. "Tropical ecology and research", British Emp.For. Conf. 1947.BURTT-DAVY, J. "The classification of tropical woodyvegetation types", Imp. Forestry Inst., Inst. Paper no. 13,1938.

Bibliography I Bibliographie

10.11.

CHAMPION, H. G. "A preliminary survey of the forest 16.type of India and Burma", Indian For. Ree. 1936 (N.S.),vol. I, p. 1-286.CHAPMAN, V. J. "The application of aerial photography 17.to ecology as exemplified by the natural vegetation ofCeylon", Indian For. 1947, vol. 73, no. 7, p. 287-314.GAUSSEN, H. "Projets pour diverses cartes du monde 18.à 1 /I 000 000. La carte écologique du tapis végétal",Ann. agron. t. XIX, Paris, 1949.KAIKINI, N. S. "The forests of Bombay State", Indian 19.For. 1954, vol. 80, no. 12, p. 783-786.KHAN, A. A. "The Andhra forest'", Indian For. 1954,vol. 80, no. 12, p. 742-745. 20.KCEPPEN, W. Grundriss der Klima Kunder. 2nd ed., 1931.NAGDEV, D. P. "The forests of Ajmere State", Indian 21.For. 1954, vol. 80, no. 12, p. 742-745.PAL, N. "Forestry in West Bengal", Indian For. 1954 22.vol. 80, no. 12, p. 759-767.RAI, L. "Forestry in Orissa", Indian For. 1955, vol. 81, 23.no. 1, p. 3-6.RICHARDS, P. W. The tropical rain forest. Cambridge 24.Univ. Press, 1952.RoSAYBO, R. S. DE. "Soils of the west zone forests of theMatara, Galle and Kalutara Districts", Trop, agriculturist 25.Ceylon, 1939, vol. 42, no. S, p. 264-278.

ROSAYBO, R. S. DE. "The soils and ecology of the wetevergreen forestsof Ceylon", Trop, agriculturist 1943,vol. 98, no. 2, p. 4-14; no. 3, p. 13-55.

. "Ecological considerations in the management ofwet evergreen forest in Ceylon", Ceylon For. 1950 (N.S.),vol. 1, no. 2, p. 80-90.

. "Ecological research in Ceylon and its applicationto practice of forestry", Proc. Ceylon Ass. Adv. Sci.(8th annual sess.) Sec. B, 1953, 26 p.

. "The silviculture and management of tropical rainforest with special reference to Ceylon", Ceylon For. 1955(N.S.), vol. II, no. 1, p. 5-26.SAHNI, K. C. "Botanical exploration in the Great NicobarIsland", Indian For. 1953, vol. 79, no. 1, p. 3-7.SCHIMPEB. Plant geography upon a physiological basis.Oxford Univ. Press, 1903.STEBBING, E. P. The forest of India. The Bodley Head,1923.STBACEY, P. D. "Forestry in Assam", Indian For. 1954,vol. 80, no. 12, p. 759-767.TEILHABD DE CHABDIN, P. "Man's rôle in changing theface of the earth", Background paper for the Wenner-Gren Foundation International Symposium. 1955.TRIMUBTI, N. "The forests of Coorg State", Indian For.1955, vol. 81, no. 1, p. 3-6.

Special ReportsRapports spéciaux

Rapport sur les problèmes biologiquesde l'Afrique tropicale humide

parG. Marlier,

Institut pour la recherche scientifique en Afrique centrale, Congo belge

Depuis quelques années, les institutions scientifiquesde divers pays de l'Afrique tropicale se sont préoccupéesde résoudre un certain nombre de problèmes biolo-giques posés par l'environnement particulier des régionstropicales humides.

L'ordre dans lequel ces questions ont été abordéesn'a pas été, en général, celui de leur importance théori-que, mais plus souvent, comme il est logique, prioritéfut donnée à l'urgence.

C'est ainsi que le problème de la nutrition des peuplesafricains fut à l'ordre du jour bien longtemps avantl'étude de la structure sociale et politique de leurssociétés.

Cette priorité se justifiait par le nombre et l'étenduedes maladies de carences nutritionnelles chez les indi-gènes de l'Afrique.

Une autre priorité fut donnée par les instances gou-vernementales à la création d'un certain nombre deréserves naturelles intégrales dont le but est de bloqueren certains endroits choisis la destruction inquiétantedes biotopes naturels par l'action humaine directe etindirecte.

Mais il est évident qu'au cours des années cette situa-tion s'est transformée par la création d'institutions derecherche pure dont le rôle est de coordonner les recher-ches entreprises par ailleurs en fonction de leur urgence.C'est ainsi que sont apparues dans les dernières annéesun certain nombre d'institutions destinées à une tellecentr alisation.

Les problèmes de la biologie des régions tropicaleshumides peuvent être répartis sous six rubriques, quine représentent pas des disciplines indépendantes maisse rejoignent en de nombreux points.

Les problèmes biologiques de la zone tropicalehumide sont, par définition, liés au milieu particulierde cette région : ce sont des problèmes liés à l'habitatet qui relèvent donc de l'écologie au sens large du terme.

Comme tous les problèmes d'écologie, leur solutionrepose sur un inventaire systématique.

Il convient donc, dans ce résumé, de commencer parles problèmes de systématique.

INVENTAIRE SYSTÉMATIQUE DES ESPÈCES ET

DES RESSOURCES NATURELLES

Nous ne parlerons ici que des travaux qualitatifs, enréservant pour un autre chapitre les problèmes quan-titatifs.

Les ressources naturelles et, en général, la flore etla faune de l'Afrique tropicale humide sont beaucoupmieux connues que celles des autres régions tropicalesdu globe malgré un départ beaucoup plus tardif. Il enest peut-être ainsi à cause de l'influence prépondérantedes nations européennes due au régime colonial.

Cette connaissance n'est cependant, et de loin, pasencore assez avancée pour que l'on puisse dire que lesrichesses naturelles de ces régions ont été inventoriées.

Mais, dans de nombreux grands groupes animaux etvégétaux, la science systématique a réalisé des mono-graphies importantes et à peu près complètes.

La flore a fait l'objet de nombreux livres et publica-tions couvrant au moins le domaine des végétauxsupérieurs, et notamment les arbres de la forêt et dela savane. Naturellement, d'autres groupes végétaux,considérés comme moins directement importants, ontété davantage négligés : les champignons supérieurset inférieurs, les algues, les bryophytes sont encorerelativement mal connus.

Parmi les animaux, les vertébrés peuvent être consi-dérés comme bien étudiés et plusieurs monographiescomplètes leur ont été consacrées récemment.

Il n'en est pas de même de nombreuses catégoriesd'invertébrés qui attendent encore leurs spécialistes.Seuls les insectes vecteurs de maladies de l'homme oudu bétail, les insectes parasites, les insectes prédateursdes cultures, les mollusques et les acariens transmet-teurs de diverses épidémies ou d'un intérêt immédiatanalogue ont réussi à éveiller l'intérêt des zoologistes.

Très peu de monographies utilisables sont à la dispo-sition des écologistes.

Cependant, il est à remarquer combien, même parmiles groupes de peu d'intérêt pratique, il est importantque des ouvrages généraux de ce genre soient écrits,vu notre connaissance fragmentaire des cycles, deséquilibres qui président à l'organisation des commu-nautés biologiques.

En outre, bien des plantes et des animaux, décrétéssans intérêt à notre époque, se trouveront promus aurang d'espèces utiles et précieuses dans quelques années.C'est à ce moment-là qu'un catalogue purement scien-tifique et systématique deviendra un inventaire desressources naturelles de la zone tropicale.

Dans cet ordre d'idées, il n'est pas inutile d'indiquerdans quels groupes on peut dès à présent prévoir undéveloppement intéressant.1. Arbres des forêts, dont peu d'espèces sont actuelle-

ment utilisées pour leurs qualités spécifiques et dontune grande quantité est gaspillée dans les exploita-tions industrielles.

2. Plantes médicinales indigènes, encore trop peu con-nues par suite principalement d'un manque decentralisation dans les études et par suite de l'absencede livres de botanique accessibles aux enquêteurs.

3. Plantes alimentaires encore inutilisées, dont la culturesystématique pourrait combler des carences nutri-tionnelles ou seulement réussir là où d'autres végé-taux non indigènes, plus classiques, donnent defaibles rendements.

4. Champignons inférieurs ou autres, dont les propriétés,comme sources d'antibiotiques, ne doivent plus êtresoulignées ici. Il ne faut d'ailleurs pas négliger leurnature éventuelle de mycorrhizes, dans le maintiendes arbres de la forêt, ni leur action nuisible commeparasites de plantes cultivées ou leur rôle éminem-ment utile dans la destruction de la cellulose desvégétaux morts. Dans ce domaine, presque toutreste à faire.

5. Animaux sauvages, dont la destruction est à peuprès assurée avec le développement actuel de lacivilisation et dont cependant la domestication oula semi-domestication pourraient se révéler fortprofitables.

Il convient, en effet, de remarquer que presque tous lesanimaux domestiques utilisés dans les pays tropicauxsont originaires des régions tempérées et sont donc,a priori, moins aptes à résister aux conditions de l'envi-ronnement tropical humide : sensibilité aux maladies,rendement plus faible, etc.

En Afrique, particulièrement, les races autochtonesne se sont pas révélées fort douées pour la domesti-cation des animaux, qui, en général, sont exploitéssans techniques rationnelles. De nombreux animauxsauvages pourraient sans doute être utilisés commesources certaines de nourriture ou comme auxiliairesà la place des espèces d'origine tempérée. Citons lesbovidés et les antilopes, les zèbres, les hippopotames,

certains grands oiseaux, de nombreuses espèces depoissons. Dans ce domaine, uniquement dans le groupedes poissons, de sérieuses tentatives, dont certainescouronnées de brillants succès, ont été faites pourdomestiquer des espèces sauvages autochtones. De là,les résultats magnifiques de l'élevage du tilapia, dugourami, etc. Il faut d'ailleurs espérer que les essaisde ce genre se poursuivront. Ils sont subordonnés,cependant, à l'existence d'études systématiques pous-sées.

Enfin, plusieurs espèces sauvages (crocodiles, élé-phants, divers reptiles, certains insectes), sources dematières premières utiles, pourraient être exploitéesplus rationnellement. Nous en sommes, dans ces cas,au simple stade de la « cueillette ».

Enfin à cet inventaire qualitatif des espèces doit sejoindre, et ce travail est déjà commencé dans certainscas, une étude des groupements (synécologique).

Ce travail, qui a pour but de déterminer les relationsentre les espèces et leur milieu (climat, sol, etc.), ainsique leurs relations réciproques, permet de définir dansquels habitats se rencontrent les espèces animales etvégétales qui nous intéressent et, au point de vue dela science pure, met en évidence les raisons de leurdispersion actuelle.

Cette étude des communautés est à peine entaméeen zoologie terrestre et en botanique, pour les régionsde savanes et de steppes. Pour la forêt dense, climaxtrès général des régions tropicales humides, seuls degrands aperçus très généraux sont à la disposition dupublic cultivé, mais tout reste à faire dans le détail.

Une connaissance complète des communautés est àla base d'une compréhension suffisante des équilibresnaturels, condition du maintien ou du développementde certaines espèces animales et végétales. Par exemple :les antilopes et bovidés de savanes sont liés à l'existencede ces groupements qui ont tendance à s'étendre et àremplacer la forêt, mais aussi à être à leur tour rem-placés par la steppe. Le maintien à l'état naturel decertaines espèces d'arbres est lié à l'existence d'animaux(éléphants, calaos, etc.) qui en digèrent les fruits etcorrodent suffisamment leurs graines pour leur faciliterla germination.

Cette étude des équilibres biologiques naturels estévidemment fondamentale pour la connaissance préa-lable du résultat de l'introduction d'une espèce végétaleou animale dans un nouveau milieu : de grosses erreursont été commises dans ce domaine dans de nombreuxpays tempérés, mais les régions tropicales humides ontjusqu'ici échappé presque entièrement à ce danger.Cependant l'élevage des tilapia par exemple pourraitdonner lieu à des introductions intempestives dans desendroits où leur multiplication ne serait pas souhai-table.

L'invasion récente des eaux congolaises par lajacinthe d'eau (Eichornia) aurait pu être évitée parl'étude des conditions de vie de cette plante indési-rable. Peut-être son eradication pourrait-elle se réaliser

Rapport sur les problèmes biologiques de l'Afrique tropicale humide

par la lutte biologique si l'on s'adressait à des bactériesou des virus vivant dans son pays d'origine.

Enfin, il importe de noter le danger que l'usage trèsrépandu actuellement des substances chimiques trèsactives comme les herbicides et les insecticides, notam-ment en aérosols, peuvent faire courir à l'existencedes communautés biologiques telles que les forêts, leplancton des eaux douces, etc.

Les forêts sont, en effet, en équilibre étroit avec lamicrofaune et la microflore du sol et de l'humus. Sices deux associations disparaissaient ou s'appauvris-saient exagérément, il est probable que les forêts nepourraient se maintenir. La connaissance approfondiedes associations animales et végétales permet de sefaire une idée de l'utilité ou de la novicité des espècessauvages d'animaux et de végétaux (insectes, moisis-sures, etc.) qui est plus complète que la conceptionclassique que s'en font les techniciens des cultures.

Enfin, des monocultures étendues ou des élevagesmassifs d'une seule espè ced'animal peuvent entraînerle développement intensif de parasites et de pré-dateurs existant déjà dans le milieu original et quitrouvent dans les nouvelles conditions un champ idéalde multiplication. Cet état de choses peut être évitépar une étude approfondie du biotope avant son exploi-tation. Ce n'est que dans de très rares cas que cetteétude a été faite en zone tropicale humide. Très souventles conditions favorables à une culture tropicale sontprécisément dues à l'existence de la forêt et pourrontdonc s'altérer si l'on fait disparaître celle-ci.

PROBLÈMES DE LA PRODUCTIVITÉ DES SOIS

ET DES EAUX

La productivité d'un milieu est le taux de productionde matière vivante qu'une association biologique déter-minée est capable de maintenir en partant des élémentsminéraux existant dans ce milieu.

Elle dépend donc non seulement de la richesse dumilieu avant sa colonisation par les êtres vivants, maisencore de 1' « efficience » de la communauté qui s'yétablit.

Son estimation est donc en somme l'aspect quan-titatif des études de groupements vivants dont il étaitquestion dans la section ci-dessus.

L'intérêt particulier de ces études dans les régionstropicales provient de la nécessité où nous sommes detrouver de nouvelles sources de production de matièrespremières et surtout de substances alimentaires pourles populations autochtones en accroissement numé-rique constant.

Or, il a régné sur ces questions des opinions diversesmais qui n'ont toujours pas été infirmées ou confirméespar des recherches suffisantes.

En effet, une opinion classique est celle de la richesseillimitée des sols des grandes forêts équatoriales, quisemble corroborée par la luxuriance et la pérennitéde ces formations végétales.

En fait, les essais de mise en valeur des étenduesarrachées à la forêt ont conduit à des déceptions quiont fait naître l'opinion opposée.

Suivant celle-ci, les sols de la grande forêt seraientpauvres et capables seulement de porter certainesassociations de végétaux sauvages, mais non uneculture à « exploitation » régulière.

Des études de bilans des différents sols nutritifs del'eau, de l'azote et du carbone organiques montrerontquelle est la capacité biogénique réelle de la forêt. Eneffet, il est possible que le sol, après abattage des arbres,soit pauvre mais que l'ensemble sol plus associationsforestières soit éminemment efficient et conduise àl'élaboration régulière de grandes quantités de matièrevivante se traduisant d'abord par la population totaleactuelle (standing crop), puis par la formation rapided'humus et de nourriture pour les populations animalesqui habitent la forêt. La confirmation de ces vuespourrait modifier grandement les conceptions actuellesen matière d'agriculture en zone tropicale humide.

Un autre domaine où ces études sont souhaitablesest l'ensemble des eaux « noires » de la forêt equatoriale.Ces eaux extrêmement riches en matières organiquessupportent une population de poissons en général trèsflorissante. Cependant, elles montrent des caractèresphysiques et chimiques qui les feraient considérer dansles pays tempérés comme très défavorables à la pisci-culture. Là encore, les investigations scientifiques sontéparses et les problèmes sont loin d'être résolus.

Ce domaine des eaux noires n'est pas particulier àl'Afrique, mais se rencontre aussi bien en Amériquedu Sud.

La productivité biologique des autres types d'eauxdouces tropicales n'a, elle non plus, pas été suffisam-ment étudiée. Notons particulièrement les fleuves etautres cours d'eau dont l'étude est à peine commencée.

Vu la remarquable réussite des cultures de poissonsen étangs, la tendance se fait jour de plus en plus dedévelopper ces cultures mêmes au voisinage des grandscours d'eau, habitats d'une faune ichthyologique indis-cutablement riche. L'étude de ces biotopes et de leurproductivité ne devrait pas négliger celle de leurszones d'inondation si remarquable pour les grandsfleuves d'Afrique, où des travaux récents ont montréqu'une importante partie du cycle biologique des pois-sons se poursuit.

Enfin, il est impossible de quitter ce chapitre de laproduction sans signaler les recherches qu'il convientde faire dans le domaine de la culture des algues alimen-taires. L'accroissement considérable de la populationhumaine dans les régions tropicales, dû particulière-ment aux progrès de la médecine européenne et améri-caine, se traduira dans les années à venir par unedéficience alimentaire dans ces régions.

Il sera alors nécessaire de se tourner vers de nouvellessources de protéines et il sera logique de s'adresser aucycle biologique le plus court et le plus efficient. Lesprogrès récents des études sur les cultures d'algues

alimentaires dans les pays tempérés montrent que lasolution de ce problème n'est pas impossible, mais ilreste à appliquer ces mêmes recherches aux pays tropi-caux; étude des algues de valeur alimentaire élevée, àefficience aussi grande que possible, de culture indus-trielle aisée.

PROBLÈMES BIOLOGIQUES LIÉS A L'ÉROSIONET AU CYCLE DE L'EAU

La question de l'érosion des sols et le cycle de l'eauproprement dit n'ont pas leur place dans ce chapitre.

Cependant, certains aspects de ces questions sontnettement biologiques et doivent être soulignés briève-ment ici.

Indépendamment des causes physiques de l'érosion,l'influence du déboisement sur les sols, de certainescultures exigeantes ou à couverture insuffisante, ladestruction de la microfaune du sol par les insecticidessont des problèmes à traiter par des méthodes biolo-giques. Le dernier particulièrement, encore très malélucidé, semble avoir une importance considérable.

En effet, la disparition de la microfaune du sol pour-rait abaisser nettement la productivité d'un sol parralentissement de la mise en circulation des matièresnutritives contenues dans les déchets du métabolismed'une association végétale. La dégénérescence du cou-vert végétal qui en résulterait pourrait être l'impulsionnécessaire au déclenchement de phénomènes d'érosionsans qu'un déboisement volontaire ait été pratiqué.

D'autre part, l'étude des phénomènes d'érosion, par-ticulièrement de la vitesse de leur déroulement, pourraitapporter des renseignements extrêmement précieux dansun domaine particulier de la recherche pure.

Il s'agit de la paléoclimatologie et de la détermina-tion de l'âge des grandes formations végétales quenous rencontrons actuellement.

La discussion est toujours ouverte au sujet de l'âgerelatif de la grande forêt equatoriale en Afrique et dessavanes incluses dans la forêt ou extérieures à celle-ci.A ce problème s'ajoute celui de l'âge comparé desforêts de l'Afrique, de l'Amérique et de l'Asie tropi-cales. S'y rattachent aussi la paléogéographie desrivières et fleuves tropicaux et l'origine de leur faune,notamment par l'étude des sédiments des lacs, celledes cycles d'érosion et les analyses polliniques desvases de marais.

PROTECTION DE LA NATURE

La protection de la nature est loin d'être une préoccu-pation nouvelle, mais ses principales organisations setrouvent dans les régions tempérées et s'appliquent auxfaunes et aux flores de pays tempérés.

Cependant, de façon assez paradoxale, ce sont lesrégions tropicales, moins industrialisées pourtant, oùles milieux naturels sont les plus menacés de la des-truction.

Les phénomènes de la régression de la forêt devantl'action de l'homme et son remplacement par la savaneet la steppe sont bien connus, mais d'importantesétudes restent à faire sur la disparition progressive desespèces d'animaux vivant en savanes, même dans lesréserves naturelles. En forêt, la faune est moins menacéede disparition sauf par la destruction du biotope oùelle vit.

De nombreuses réserves naturelles ont déjà été cons-tituées en Afrique, notamment au Congo belge, maisl'inventaire de leurs richesses n'est pas terminé, nil'étude de la densité optimale de chacune des espècesà protéger et des conditions écologiques de leur sub-sistance.

Ces réserves sont d'ailleurs pratiquement les seulsendroits où il soit possible à l'heure actuelle d'observerle comportement normal des animaux sauvages.

LE CLIMAT ET SON INFLUENCE SUR L'HOMMEET LES ANIMAUX

II n'est pas question ici de décrire le climat des régionstropicales humides ni les réactions de l'homme primitifdans ces régions.

Il m'appartient seulement de signaler brièvement lesproblèmes biologiques nés de l'existence d'êtres humainsdans un climat aussi particulier.

Ces problèmes sont de deux types : problèmes physio-logiques de l'action directe du climat sur l'autochtoneet sur l'homme blanc, et problèmes de la résistancepassive ou active aux maladies tropicales.

Le premier de ces problèmes est abordé par l'étudede l'habitation tropicale : il s'agit de l'habitation quese construisent les indigènes des régions tropicales etoù ils ressentent le confort le plus complet, compatibleavec les ressources en matériaux dont ils disposent.Dans ce domaine, puisqu'il semble souhaitable deconstruire des habitations permanentes convenant àun genre de vie sédentaire, il faudra se conformer àla notion que se fait l'aborigène du confort et non àlui appliquer les normes de l'homme blanc.

Il n'est d'ailleurs pas prouvé que, pour celui-ci éga-lement, le climat de l'habitation indigène ne sera passupérieur à celui des habitations qu'il se construitactuellement et qui sont calquées sur celles des paystempérés.

Le problème génétique de la résistance plus grandede l'Africain aux rigueurs du climat tropical n'est pasencore résolu lui non plus. Il est cependant fondamentalde savoir si certaines zones tropicales doivent êtreprohibées à la colonisation de peuplement ou si seule-ment interviennent des questions d'hygiène et destanding économique.

A côté de l'action du climat proprement dit, vientl'ensemble des problèmes des maladies.

Évidemment, il s'agit ici d'un champ de recherchesdéjà extrêmement bien prospecté par les services médi-caux de tous les pays de la zone tropicale. Il comprend

Rapport sur les problèmes biologiques de l'Afrique tropicale humide

l'étude des cycles des agents des grandes maladiestropicales (malaria, trypanosomiase, fièvre jaune,schistosomiase et autres helminthiases, mycoses diverseset de leurs vecteurs. Il comprend aussi l'étude de cesdiverses maladies chez les animaux sauvages et domes-tiques ou des maladies que l'on peut considérer commeà l'origine de celles de l'homme.

Dans ce domaine, il convient de rappeler l'étude dela fièvre jaune de forêt, qui s'attaque particulièrementà diverses espèces de singes et qui repose sur un cyclede vecteurs qui n'est pas encore entièrement élucidé.De même les divers plasmodiums que l'on peut ren-contrer chez des mammifères sauvages où ils suiventun cycle assez comparable à celui des parasites del'homme. De là, l'intérêt de la découverte du plasmo-dium berghei qui peut s'élever aisément sur mammi-fères de laboratoire.

Les diverses trypanosomiases, elles aussi, sont étu-diées en fonction de la susceptibilité de certains animauxsauvages à l'infection : ces recherches permettent d'espé-rer une solution à la controverse sur le rôle réel dugibier comme « réservoir à virus ».

Enfin, il convient de ne pas oublier que le cas de laschistosomiase humaine n'est pas encore résolu. Ils'agit ici d'un des plus grands obstacles à la mise envaleur de régions entières par les cultures irriguées etinondées. Cette maladie est causée par un ver qui esttransporté par des mollusques pulmones. Le problèmede l'éradication de la maladie repose donc sur l'étudede l'écologie du transmetteur autant que sur l'exter-mination des parasites dans l'organisme des malades.

La suppression des mollusques autant que la cure desmalades présente, semble-t-il, de grosses difficultés.

Les mycoses diverses, maladies fort peu répanduesdans les pays tempérés, sont au contraire florissantesen régions tropicales humides. Bien qu'il soit relative-ment rare de leur voir prendre une importance égale àcelle des maladies précédentes, elles sont souvent assezcommunes pour revêtir au moins une certaine signifi-cation sociale.

Bien que l'on puisse supposer que beaucoup d'entreelles disparaîtront avec le développement de l'hygiène

chez les indigènes, on peut être sûr que certaines semaintiendront comme elles le font en régions tem-pérées. Il convient donc d'en faire l'étude systématiquetant au point de vue étiologique qu'au point de vuethérapeutique.

Les maladies du bétail sont également nombreuseset peuvent, tels le nagana ou les helminthiases, repré-senter un obstacle sérieux à l'élevage dans des régionsdéfavorisées. Ces dernières sont également, dans beau-coup d'endroits, des causes de dépréciation de la viandeprovenant d'élevages indigènes.

PROBLÈMES DE LA NUTRITION HUMAINE

Dans les régions tropicales, particulièrement en Afrique,il est reconnu que l'homme a une nutrition carencéeen plusieurs éléments.

Les problèmes de maladies de carence sont étudiésdepuis de nombreuses années et la création de labora-toires modernes sous les tropiques permet actuellementde les aborder plus intimement.

Aux questions médicales proprement dites doiventse joindre des études sociales sur la qualité et la quan-tité d'aliments absorbés par les indigènes dans lesdiverses circonstances de la vie. Il faut en outre exa-miner la composition chimique des différents alimentsutilisés dont la carence en certains éléments pourraitcauser les maladies observées.

Ces trois types de recherche sont en cours actuelle-ment au Congo belge, sous les auspices de l'Institutpour la recherche scientifique en Afrique centrale,notamment dans le domaine du kwashiorkor, maladiede carence protéinique, que l'on a pu récemment pro-voquer expérimentalement chez le porc et dont, d'autrepart, on a pu obtenir la guérison chez l'homme.

Des enquêtes alimentaires, dans différents milieuxindigènes, se poursuivent au Ruanda-Urundi depuisplusieurs années.

Enfin, la composition chimique des principaux élé-ments de l'alimentation indigène est étudiée systéma-tiquement au Congo belge depuis 1948 par la Missionde la nutrition.

Report on Biological Problemsin the Humid Tropical Zone of Africa

byG. Marlier

Résumé

For some years past, scientific institutes of various 2. Problems of the productivity of soil and watercountries in tropical Africa have been attempting to courses.solve a number of biological problems particular to 3. Biological problems connected with erosion and thehumid tropical areas. Biological problems in humid rain water cycle.tropical areas can be classified under the following 4. Protection of Nature.six headings: 5. Climate and its influence on man and animals.1. Methodical inventory of natural species andresources. 6. Problems of human nutrition.

A Report Reviewing EntomologicalProblems in the Humid Tropical

Regions of South Asiaby

Dr. A. P. KapurZoological Survey of India, Calcutta

INTRODUCTION

The present report, written at the instance of Unesco,is intended to review entomological problems in thehumid tropical regions of South Asia, with specialreference to India. It was also desired by Unesco thatthe report should review fundamental entomologicalresearch so far carried out for the solution of thoseproblems and suggest lines along which further basicresearch should be undertaken.

Many who have lived in the tropics will appreciatethe importance and magnitude of entomological prob-lems in these parts. Insects surpass all other classesof animals in respect of numbers and variety. Onaccount of the great richness of vegetation and variedphysiographic features in the humid tropical regionsof South Ásia, the insect life is both more varied andmore abundant than in other parts of Asia. Manyinsects damage crops and stored products while othersare vectors of a formidable list of human and cattlediseases. In South Asia, moreover, entomologicalproblems assume even greater significance than inmost other tropical regions because of the high densityof human population whose economic ameliorationlargely depends on improved agriculture and betterhealth.

Although one could trace the association of insectsand man to times before the dawn of civilization andin the early scriptures of the ancient Indians, it wasnot until the last quarter of the nineteenth centurythat sustained entomological work began to be actuallydone in India and the neighbouring countries. Rossin 1898 made history in medical entomology by discover-ing in India the role of mosquitoes in the transmissionof malaria and official recognition was soon afterwardsgiven to the entomological needs of the country notonly in the medical but also in other fields. The follow-ing 50 years have seen considerable progress in entomo-logical research and its application in India, Burma,Ceylon and lately in East Pakistan. In view of the

importance of the subject and the considerable amountof work done for over half a century, it is very difficultto write an adequate report. There has been no dearthof material; the main difficulty has been in decidingas to what should be discarded in view of the limitedspace and time at the writer's disposal. Inevitablythere will be omissions both in subject and in namesof workers and it is hoped that these shortcomingswill be overlooked.

The writing of the report would have been far moredifficult had it not been for the fact that several valuablereviews on the progress of entomology in India hadappeared already in various publications. Specialmention may be made of those by Mr. M. Afzal Hussain[191],1 Dr. H. S. Rao [321], Dr. B. C. Basu [36] andDr. M. L. Roonwal [332]. The present writer is greatlyindebted to these writers and also to the followingwho have generously helped him by sending notes orreferences: Mr. Ananda Rau, entomologist, UnitedPlanters' Association of Southern India; Dr. K. K.Nirula, entomologist, Indian Central Coconut CommitteeMr. V. Tirumalarao, entomologist, Andhra State;Mr. W. J. Ellis, head, Unesco Science Co-operationOffice for South Asia, New Delhi; Dr. S. N. Banerji,entomologist, West Bengal; the President, ForestResearch Institute, Dehra Dun; the Plant ProtectionAdviser to the Government of India, New Delhi;the Director, Jute Agricultural Research Station,Barrackpur, Calcutta ; the Director, Indian Lac ResearchInstitute, Namkum; the Director, Tea Research Insti-tute of Ceylon; the Director, Coconut Research Insti-tute of Ceylon ; the Director, Rubber Research Instituteof Ceylon. To Dr. W. J. Hall, C.M.G., M.C, Director,Commonwealth Institute of Entomology, London, andto Dr. S. L. Hora, F.N.I., late Director, ZoologicalSurvey of India, grateful thanks are due for theirvaluable suggestions on the writing up of the report.

1. The figures in brackets refer to the bibliography on page 77.

INSECT PESTS OF AGRICULTURAL IMPORTANCE

Although there is a great variety of cultivated cropsand plantations in the humid tropical parts of SouthAsia, the present chapter deals with the main entomo-logical problems of paddy, sugar-cane, jute, coconutpalm, tea and coffee only. Rubber, fortunately, doesnot suffer much from insect depredations and is there-fore excluded from consideration. Certain other cropswhich are not so important economically have also beenleft out. A section has however been devoted, at theend of the chapter, to insect vectors of plant virusesbecause the problems presented by them are differentfrom those of other insect pests and therefore requirespecial consideration.

Paddy is far and away the most important crop grownin humid tropical parts of South Asia.

It is attacked by some forty different kinds of insects ;about seven of these with fairly wide distribution maybe classified as pests of major importance. Six moreappear sporadically and cause considerable losses incertain years. The seven major pests are: Schnoebiusincertellus (the rice stem borer), Spodoptera mauritia(the rice swarming caterpillar), Cirphis unipunctata(the paddy cutworm), Hispa armigera (the rice hispa),Leptocorixa varicornis (the paddy bug or gundhi bug),Pachydiplosis oryzae (the paddy gall fly), and Hiero-glyphus banian (the rice grasshopper).

Information on the distribution, life history andalternative host plants of these insects is available inseveral publications, by Lefroy [237], Fletcher [116,117], Sheroff [349], Ayyar [26, 28], Ghosh [154] andothers. An important feature of the pests of paddy isthat large populations appear in the fields, as ifsuddenly, and cause intensive damage. Besides theproblem of rapid multiplication in the paddy fieldsthemselves, the question of migration of these insectsfrom neighbouring wild, alternative, host plants isalso involved and therefore clean cultivation has beenrecommended as a measure of control for almost allthese pests. Climate obviously plays a significant rolein the increase of their population. The rice stemborer, for instance, appears as a more serious pest incertain rain-fed areas than in others. The variousclimatological factors that are involved have not,however, been critically studied in the case of paddypests.

The larvae of rice hispa mine into leaves, and thoseof the rice stem borer and the paddy gall fly bore intothe stem, with the result that chemical means of controlare rendered ineffective unless taken as a prophylacticmeasure or completed during the short period of theinsect's life, prior to its boring into the plant tissue.The farmer, who is generally reluctant to invest inprophylactic measures and is often confronted with

the practical difficulty of completing spraying opera-tions in the brief period of the insect's life before itbores into the plants, suffers great losses from thesepests. The paddy bug presents similar problems. Ithas a number of host plants but whereas its youngones feed on plant sap, the adult bug shows preferencefor the milky juice of the ripening grain, and as soonas the ears are formed and grain set, large populationsof the bug render the crop useless in a very shorttime.

An important problem relates to the large-scale useof chemical insecticides as a plant protection measure—there are already indications of the change in statusof certain pests which were hitherto considered to beminor pests. Either because their insect parasites andpredators are killed by powerful insecticides or for someother little-understood reason, the population of thesepests increases. Such a situation seems to have arisenin Ceylon in respect of the bug Scutinophora lurida.Similar situations may also come to light in India ifinvestigated carefully. Informally, the reviewer gath-ered from the Entomologist, West Bengal, that about athousand acres in Malda district were recently infestedby So gata sp., in fields which were previously beingtreated with BHC against the rice swarming cater-pillar and the rice hispa. The local farmers are reportedto have said that they had never before seen theirfields being damaged by these bugs. Apart from arecord by Fletcher [117] of three species of Sogatahaving been "found in some numbers on paddy whenNephotettix was being investigated" at Pusa, Bihar,there is perhaps no other information available on thisinsect's association with paddy.

A detailed study of the insects as well as of theirenvironments, especially of the factors which lead tothe rapid increase of their populations, needs to bemade with a view to more effective control measures.

Sugar-cane

Since 1931, when the Government of India grantedprotection to this industry, the acreage under sugar-cane has increased considerably. Sugar-cane is attackedby over fifty species of insects and mites of which thefollowing are important—moth borers: Chilotraea infu-scatellus, C. auridlia, Chilo tumidicostalis, Procerasindiens, Bissetia steniellus, Sesamia inferens (stemborers), Scirpophaga nivella (top-shoot borer), Emma-locera depressella (root borer); sucking insects: Pyrillaperpusilla (the sugar-cane hopper), Aleurolobus baro-densis (the cane white fly), Trionymus sacchari (thecane mealy bug); termites: Odontotermes spp. (whiteants).

Useful work has been done during the last twentyyears or so by many workers on the moth borers ofsugar-cane in India. The life history and seasonaloccurrence, alternative host plants and geographicaldistribution of the species in various parts of Indiaare generally known. Systematic studies on Crambine

Entomological problems in the humid tropical regions of South Asia

stem borers have been recently monographed by Kapur[214]. Statistical studies of losses caused by borersand termites and studies in sampling techniques weremade by Pruthi et al [315] and Khanna et al [220]respectively. Interesting work has also been done onthe resistance of different varieties of cane to certainborers [179, 314] and their relation to the spindlelength of leaves, the hardness of midrib and of rindof different varieties [221, 223, 322].

The influence of climate, season, soil conditions, etc.,on the incidence of certain borers has also receivedsome attention. In Uttar Pradesh the attack of E.depressella is heavy in non-irrigated areas and at placeswhere the soil is sandy loam [174], while soil moistureis an important factor for the propagation of B. steniellus[170]. In Hyderabad the population of C. infuscatellusincreased under high temperature and low humidityconditions [364].

Cultural and mechanical measures of control evolvedby various workers included the collection and removalof egg masses and dead hearts, deep harvesting incertain cases, earthing up of sugar-cane at an earlystage of growth in fertile soil and shifting of plantingtime in certain localities. Owing to the nature of theattack by borers, applications of BHC or DDT havenot given universally satisfactory results. However,BHC dust applied in furrows at the time of plantingof cane, tried as a control measure against termites,showed comparatively low attack of A. infuscatellus.The reports hitherto received from the Punjab, UttarPradesh and Madras are favourable, although theexact manner in which this treatment acts is littleunderstood [171, 356]. The position regarding the biolo-gical control of sugar-cane pests has been summarizedby Gupta [169, 172] thus: "The biological control ofsugar-cane pests, barring trials with the egg parasiteTrichogramma evanescens minutum Riley, has not beenseriously attempted anywhere in India." Considerableknowledge has, however, been gained on the life history,distribution, extent oí parasitism, etc., of many indi-genous parasites.

Next in importance only to sugar-cane borers, thesugar-cane hopper, Pyrilla perpusilla, has gained noto-riety in almost all the sugar-cane growing tracts ofthe country. Previously referred to under three species,its systematic position has been cleared up by Pruthi[310]. Its population increases suddenly during certainseasons and results in epidemics which cause severelosses, especially to the quality of the cane. The lifehistory of the pest is known and it is believed that inUttar Pradesh easterly winds and high atmospherichumidity during May and June help the pest to thriveduring hot weather and increase a great deal with thebreak of the monsoon. Intermittent periods of droughtin subsequent months further help the increase of thePyrilla population. Heavy manuring and frequentirrigation are also conducive to the multiplication ofthis species. Studies in sampling techniques for estimat-

ing Pyrilla incidence, varietal resistance, and the'effectof BHC and DDT on the pest and the quality of crop,have been made by Khanna, [219] and others. Differentstages of Pyrilla are attacked by a variety of predatorsand parasites. The collection of egg masses in earlyseason and the trapping of nymphs in wire nets toallow the exit of parasites have been recommended forreducing the incidence of Pyrilla. Intensive cultivationall through the year has given opportunity to theseinsects to become perennial pests in certain parts ofSouth India [28]. Excess of nitrogenous manures alsoincreases its incidence [262].

The cane mealy bug, and the cane white fly aregenerally more serious in humid tracts and have; likePyrilla, a number of important insect predators andparasites, which deserve to be protected against theindiscriminate use of insecticides.

The termites presented a serious problem at thetime of planting sugar-cane setts, but in recent yearshave been satisfactorily controlled by use of BHC,DDT, aldrin and dieldrin. It is interesting to observethat chlordane, perhaps because of its stimulatingfertilizer effect, enhanced the germination of the setts[350] while methyl bromide (used as a soil fumigant)against rats and white ants had an adverse effect onthe crop or germination of setts [320].

Jute is the most important cash crop of East Pakistanand India. The entomological problems here mainlycentre round some half a dozen species of insects andmite which constitute major pests, though there areseveral other species which are associated with the jutecrop and require investigation from time to time. Themajor insect pests are: Diacrisia obliqua (the hairycaterpillar), Anomis sabulifera (the jute semilooper),Laphygma exigua (the cutworm), Apion corchori (thejute apion), and Hemitarsonemus latus (the yellowmite).

Experiments conducted at Dacca (East Pakistan)showed that about 20 per cent of the crop may be lostowing to the attack of three species of caterpillars andof the mite mentioned above [92].

Diacrisia obliqua, the hairy caterpillar (also calledthe Bihar hairy caterpillar), is widely distributed inNorth India and destroys a variety of crops. It appearson jute when the plants are about 3 feet high. Theyoung caterpillars remain gregarious for about a week,but later on disperse in the field and, in years of heavyattack, the plants may be completely defoliated. Theyare controlled by the application of the usual stomachand contact insecticides.

The jute semilooper is, as the name implies, a specificpest of jute. It appears on 2-foot-high plants, feedsmostly on tender leaves and sometimes on youngshoots at the top. Not only is the growth of the plantthus affected, but as damage to the top induces growthof side shoots, the quality of the fibre is also impaired.

Years with late rains, and consequently late sowing,appear to be conducive to the multiplication of thepest [110]. On the other hand, the cutworm, Laphygmaexigua, which is a destructive pest of jute seedlings,appears in large numbers in early sown crop in yearsof early rains. This species is widely distributed andis polyphagous, probably feeding on almost any low-growing plant.

The jute apion was until recently considered to beonly of occasional importance. However, as a resultof recent investigations [90]. it was shown to be animportant pest which affected the quality of fibre.It is widely distributed in all jute-growing areas; ofthe two cultivated species of Corchorus, C. capsularisis more susceptible. The mucilage which is secreted,as a result of injury to the stem by the weevil grubwhich bores into it, firmly binds the fibre bundles withits adjoining tissue and results in what is known inthe trade as the "knotty fibre". The life history ofthe pest, location of the attacked parts in relation toearly or late sowing, and the effect of certain manureson the incidence have been investigated. Superphos-pates and potash are stated to decrease the incidencewhile the reverse is true of nitrogenous manures.Spraying with organic insecticides is stated to behelpful.

The yellow mite, Hemitarsonemus latus, is moreserious than the red mite, Tetranychus bioculatus,which is also found on jute, tea, etc. According to Das[92] the yellow mite, owing to its minute size, escapesnotice and is more prevalent in highland areas thanin lowlands. Fletcher [117] considered jute mites tobe unimportant as a rule in the wetter districts wherejute is grown. Dutt [110], however, observed thatearly rains, high humidity and early sowing werecorrelated with its incidence.

The literature on jute insects shows that the realstatus of many of the insects is inadequately known.About a dozen species have been recorded as "pests"for the first time during the last decade or so. Severalother insects which were considered as minor pestshave come to be regarded recently as pests of majorimportance. A thorough survey of jute insects andtheir natural enemies, and an assessment of the lossescaused by them in the quantity and quality of thefibre, are needed. Ecological studies of the pests andtheir relation to cultural practices and insecticidesare also necessary, especially for the purposes of makingtimely forecasts and working out suitable methods ofcontrol.

Coconut Palm

The humid tropical region of South Asia constitutesone of the most important coconut producing areasin the world. Although there are some twenty speciesthat have been recorded as pests of coconut palm,only three of these are regular pests while a few othersassume status of a pest in certain years only. The

three major pests are: Oryctes rhinoceros (the rhino-ceros beetle), Rhynchophorus ferrugineus (the red palmweevil), and Nephantis serinopa (the black-headedcaterpillar).

The rhinoceros beetle is a serious pest in India,Burma, Ceylon and East Pakistan and occurs also inJava, Sumatra, Malaya and the Philippines. Theincidence of attack is greater near populated areas andforests, where breeding spots are plentiful. The beetlesbore into unopened fronds and when the damageextends to the growing point the tree begins to die,the loss being greater in young plants. Since the youngerstages of beetles are passed in decaying vegetablematter such as manure heaps, leaf stalks, and decayingpalm logs, etc., the control measures have thereforebeen directed towards the destruction of eggs, larvaeand pupae in such breeding places. Organic insecticideslike BHG and DDT have recently been employed forthe purpose, especially by Nirula and his colleagues atKayangulam Research Station. Investigations onnatural enemies have also been made, though attemptsto import the Scoliid wasp, Scolia ruficornis, fromZanzibar have so far not been successful.

The red palm weevil is also very destructive and ishelped in its depradation by toddy drawers who inflictcuts on the palm and also by the rhinoceros beetlesthat bore into the palm—since the weevil lays eggsin cuts and injured parts of the palm. Unlike therhinoceros beetle its immature stages develop onthe palm tree. Palms of all ages are destroyed butyoung palms are the worst sufferers. Apart from keep-ing the plantation clean and dressing cuts and woundswith repellents, there is hardly any measure that hasbeen usefully recommended for its control. Investiga-tion of the ecological, biological and chemical meansof its control is required. Of the various organic insecti-cides, pyrethrins-piperonyl butoxide did not showphytotoxic effect on tender palm tissues in field trialsmade at Kayangulam.

The black-headed caterpillar is a serious pest in thecoastal plains of South India, in Orisan and Bengaland in Burma, Ceylon and East Pakistan. It causesextensive damage to coconut fronds and althoughpresent throughout the year, it generally appears inepidemic form from March to June. A serious attackbrings about a steep fall in the production of nuts,but the tree is seldom if ever killed as a result of it.Fortunately the attack is also localized. Ecologicalstudies on the pest have been in progress to study thefactors responsible for the fluctuation of population.The pest has a number of natural enemies in a varietyof insect parasites and predators arid offers prospectsfor a successful control by biological means. In themeanwhile, experiments with organic insecticides haveshown that 0.2 per cent DDT spray gives satisfactoryresults in the field. Since great caution has to be exer-cised in undertaking such measures of control, lest bene-ficial insects are seriously affected, trials on the toxicity

of new chemicals to parasites and predators are alsobeing made.

Recently the cockchafer, Leucopholis coneophora, hasbeen recorded as damaging roots of coconut palms incertain parts of South India. Among other insects ofcoconut palm may be mentioned two or three speciesof slug caterpillars which appear as sporadic pests indifferent areas. The castor slug, Parasa lepida, is oneof them and is also an occasional pest in Ceylon. Anotherslug caterpillar, Contheyla rotunda, has appeared inepidemic form in Malabar and Travancore-Cochin Statefrom time to time. Certain coccids like Aspidiotusdestructor become sporadically abundant on leaves,while a mealy bug is transported to inflorescence bythe ant Oecophylla smaragdina, which if controlled isexpected to stop the infestation.

Although a great deal is known of the pests of coconutpalms, further investigations on their ecology andnatural enemies should be undertaken with a view toevolving such suitable means of control as wouldreduce the need for chemical control to the minimum.Great scope exists for co-ordination of work on certainmore widely distributed pests between South Asianregions and other parts of the world where similarproblems on coconut palms are being tackled.

The importance of tea cultivation in humid tropicalregions of South Asia cannot be over-emphasized. Thereare several kinds of insects and mites which poseproblems in tea cultivation and have received consider-able attention during the last 50 years or so. Some ofthese create problems of a more chronic nature thanothers. A few, such as the mites, are coming to thefore since the application of powerful organic insecti-cides. The following insects and mites may be speciallyconsidered, out of a long list of arthropods associatedwith tea in South Asia: Helopeltis spp. (the tea mosquito)the tea mites (the red spider and the crimson, purple,pink and yellow mites), Xyleborus fornicatus (theshothole borer of tea), Homona coffearia (the tea tortrix),Bistort suppressaria (the common looper caterpillar),Heterusia virescens (the red slug and other Limacodidae),Andraca bipunctata (the bunch caterpillar), and thetermites or white ants.

The so-called tea mosquito in North-East Indiabelongs to Helopeltis theivora, whereas in South Indiaand Ceylon H. anioni appears to be the chief species.Helopeltis has perhaps received greater attention inIndia than any other species associated with tea. Itslife history, habits, nature of damage to tea and alter-nate host plants are well known. Valuable informationon its incidence as related to climatological factors andsoil composition, acting directly or indirectly throughthe agency of the plant, has also been gathered aftermany years of work. Helopeltis is at its worst duringthe rainy season. Centres of infection remain wherethere is a local warm and humid patch of tea, sheltered

from air currents and shaded. The infection spreadsthrough an area of tea when the atmosphere is warmand moist and the attack remains severe as long assuch conditions last. When the atmosphere becomeseither colder or drier, the epidemic dies away. Forthis reason many gardens make it a practice of clearinga belt of jungle round the edge of their tea, but as thejungle grows up again by the end of July such a practicemerely delays the advent of the epidemic or at best,reduces the epidemic outbreak to a normal one. Catch-ing the bugs by hand is practised quite often and hasled to interesting observations being made on thehabits of the bug, the nature of attack and signs offresh and old injuries on leaves and shoots. Recognitionof fresh injury helps in spotting bugs, which are notstrong fliers and remain concealed in the daytime.

Since the advent of organic insecticides like DDT,it has been found possible to kill Helopeltis and bringback tea to full plucking. The outstanding advantageof DDT is its residual efficiency—it keeps bushesimmune to Helopeltis attack for about a month afterapplication. Rau [326], giving the example of CentralTravancore which suffered from Helopeltis attack inthe past, compares the tea production figures of thisdistrict for 1949-54 with those of the previous fiveyears (1944-48) and records an increase of nearly 42 percent in tea production compared to only 13 per centover the same period for the total production of SouthIndia.

In North-East India the red spider (Paratetranychusbioculatus), the pink mite (Acophylla steinwedeni) andpurple mite (Calacarus carinatus) are known to occuron tea, while in the south, in addition to the red spiderand purple mite, the scarlet mite (Brevipalpus obovatus)is also present. The latter and the yellow mites (Tarso-nemus translucens) are of great importance in Ceylon.

Depending upon the species, various measures ofcontrol are advised. In the case of the red spider, forinstance, the control centres round cold weather defo-liation, spraying or dusting with acaricides (usuallydone twice each season, for want of a suitable acaricidethat will kill the eggs). The work has so far been con-fined to the testing of various available acaricides fromthe points of view of taint, phytotoxicity and acaricidalefficiency, but a vast field remains to be covered byfurther research on mite problems in tea cultivation.There is also a great need for further taxonomic studiesof the mites of South Asia.

The shothole borer of tea, Xyleborus fornicatus,occurs throughout the Indo-Malayan region. It boresinto small branches and twigs of a number of plants,including tea and several trees used for shade in teagardens. In living tea bushes, the shoots are killed orbreak off. The castor oil plant is perhaps the principalhost ; the damage that it causes to tea bushes in Ceylonis the chief reason for the amount of attention thathas been paid to it. In South and North-East India,tea is rarely attacked by it. In Ceylon it has been

found that application of manure containing nitrogen,phosphoric acid and potash increases vigour of growthof tea bushes, promotes quicker healing of exit holesof the borer and thus reduces the population of theborer. An annual application of the manure will main-tain these advantages. Cultivation of castor plant astraps showed little advantage. Chemical control byapplication of poisonous paints after pruning appearsto be uneconomical and the scorching of bushes unsatis-factory. Proper disposal of the prunings of bushes isessential to ensure the death of the borers in the bran-ches attacked. Various methods of doing this have beentried but none has been found entirely satisfactory. Acompromise is to strip off the leaves and twigs ofpencil thickness and bury them, while the thickerbranches are burned and the ashes broadcast.

Homona coffearia, the tea tortrix, is another majortea pest in Ceylon. The caterpillars feed on youngleaves and shoots and cause serious damage to theflush of tea and coffee, and to a number of other plantsincluding certain shade, trees. A considerable amountof work has been done on it, including biologicalcontrol, especially by the introduction of exotic para-sites [134].

Of about eight different species of looper caterpillarsoccurring on tea, the common looper caterpillar Bistonsuppressaria is regarded as a sporadic pest of majorimportance in North-East India. So serious is thedamage it causes that even a dozen caterpillars cancompletely strip off the leaves of a bush in a few days.Das [93] states that in 1947 over 50 Assam tea estateswere visited by epidemic outbreaks of it and thatduring the epidemic more than 7,000 maunds(574,000 pounds) of caterpillars were collected by handlabour. Andrews (1931) believed that the looper cater-pillar has become important since the introduction ofshade trees, a large variety of which are also attacked.Planting of Bor medeloa, which is a favourite host,as a shade tree is not advised. Control measures includedestruction, especially early in the season, of moths,eggs and caterpillars. It has been found that one appli-cation of 0.25 per cent DDT spray gives satisfactorycontrol of the looper and does not affect the foliageor taint the made tea. In places with a scarcity of"water, 10 per cent DDT dust, though less effectivethan spray, may be used, but experiments reveal thatBHC taints the made tea. To give correct treatmentto tea bushes after the attack of the looper is as impor-tant as controlling the pest itself. Such treatment maymean throwing out of plucking for a certain timebushes that have been defoliated. There is, however,very little information available on the climatologicaland other factors which lead to such sporadic outbreaks,nor have other biological (in a broad sense) means ofcontrol received due attention.

There is practically the same position with regardto the nettle grubs or "slugs" (Limacodidae), of whichHeterusia virescens, the red slug, in South India, if.

magnifica in North-East India and H. cingala in Ceylonmay be mentioned. Another lepidopterous insect ofimportance is Andraca bipunctata which occurs inAssam, Cachar and Sylhet. The larvae occur in conspi-cuous clusters and are called the "bunch caterpillars".These can eventually eat away all the leaves.

Termites are a serious menace to tea cultivators fora variety of reasons, such as direct damage to livingbushes, to dead branches, stem and roots, and toshade trees; the fertility of soil is also affected in thecase of mound-building species. Termite problems areuniversal in almost all tea-growing areas and variousspecies are involved. Control measures with the aidof organic insecticides of different kinds and brandsare proving effective. Research on the ecological andbiological aspects of termites of humid tropical regionswill result in a better knowledge of the various problemsand help in their solution. Work on the systematicsand biology is in progress at the Indian Forest andAgricultural Research Institutes respectively.

It will be observed that the entomological problemsof tea are as important as they are interesting. Consi-derable research has been done on them during thelast fifty years and remarkable progress made at thethree chief research centres, at Tocklai and Nilgirisin North-East and South India respectively, and atTalawakelle in Ceylon. Some of the results of researchare of fundamental value and are capable of widerapplication in other fields of agriculture, but are unfor-tunately not as widely known as they deserve. Investi-gations on means which would enable an accurateforecast to be made of the outbreaks of pest epidemicswould appear to be a fruitful line of work, enablingplanters to combat the pest in time.

Coffee

Coffee, which is an important crop grown in the hillplantations of South India, is subjected to attack byseveral insects of which Xylotrechus quadripes, thecoffee white borer, is the most destructive. The arabicacoffee bushes are regularly attacked; robusta andliberia coffee are less liable to attack unless weakenedby other causes. The larvae bore into the stem ofyoung plants, which are killed outright, but the oldertrees may survive the attack of several larvae. Thelife history and alternative hosts are known. Controlcomprises cutting out attacked bushes, collection byhand and destruction of adult beetles and eggs, white-washing of bushes or the application, especially bybrushing, of insecticides with residual effects just beforeeggs are to be laid in crevices of the bark.

Next in importance are the green bug (Lecaniumviridi), the mealy bug (Pseudococcus spp.) and the redbug (Saissetia hemisphaerica), although the formeris the more destructive of the two; in certain estatesin Ceylon, the green bug causes very serious damage.The factors which are responsible for its sporadicsevere attacks are not fully understood. Spraying with

certain organic contact insecticides is recommended asa measure of control. The mealy bug has come intoprominence more recently in some parts of Coorg andits decrease and dispersal are stated to be influencedby the south-west monsoon and by ants. The coffeeplant bug Antestia cruciata, though not serious inSouth India, is reported to be a very bad pest in Africa.Another exotic pest of importance is Chryphalus hampei,against whose introduction and establishment greatvigilance is being exercised in India.

A thorough survey of the pests of coffee and a detailedstudy of the ecology of some of the known as well asthe potentially important pests needs to be made witha view to evolving suitable ecological means of control.

Insect Vectors of Plant Viruses

Although virus diseases of plants were recognized bythe end of the last century, they have come to the foreonly during the last two or three decades. In Indiathe spike disease of sandal, which is a virus diseasebelieved to be transmitted by insects, is estimatedto cause an annual loss of 1 million rupees in Coorg,Mysore and Madras [39]. An intensive survey of thefauna of sandalwood was undertaken to find out thepossible insect vectors. Virus disease causing tobaccoleaf curl over wide areas was studied by Pruthi andSamual [313] and the tobacco white fly, Bemisia tubaci,found to be the vector involved. It caused similardisease in certain wild solanaceous plants which wereits alternative hosts and which served as reservoirs forthe virus. Sugar-cane mosaic in India has likewisebeen known to be transmitted by aphids, which thoughnot serious pests by themselves on that crop, deserveto be controlled in order to check the mosaic.

In recent years considerable attention has been paidto a study of virus diseases in India and has resultedin the discovery of several insect vectors. The leaf curlof tomato and of papaya, the yellow-vein mosaic ofbhindi or lady's finger and of pumpkin are transmittedby white flies, while for the mosaic of chillies, Aphisgossypii acts as a vector. The latter species of aphid,as also Aphis maidis and Myzus persicae, act as vectorsof mosaic disease of maize. Another aphid, Pentalonianigronervosa, acts as a vector for the virus causing"Katte" disease of cardamom [370].

It has also been found that the yellow-vein mosaicviruses of pumpkin and bhindi could be carried simulta-neously by the white fly wherein the incubation periodof yellow-vein mosaic of pumpkin was nine hours. Thewhite fly also retained virus for the rest of its life. Inthe case of the "little-leaf" disease of bTÌnjal, the incu-bation period of the virus in its vector, the leaf hopperEutettix phycitis, was reported to be between 10 and12 days. There is no doubt that, as further investiga-tion into virus diseases in India and neighbouringcountries are made, more will be known of the roleplayed by insects. Recent researches in other countrieshave shown that some at least of the leaf-hopper-

transmitted viruses actually multiplied inside theirinsect vectors, and that in certain cases the viruliferousfemales would transmit virus to their progeny throughthe egg and that the virus was capable of being main-tained through a number of generations over longperiods [361], Certain biting insects have also beenincriminated as virus vectors.

The control of insect vectors of virus diseases ofplants presents special problems as compared to thecontrol of insect pests. In the latter case the chiefobject is to keep the infestation below a number atwhich the damage is done. In the case of insect vectorsthe objective is a more thorough elimination of theactive stages, such as the winged form of viruliferousaphid ox white fly that move about spreading the virus,rather than to bring about the reduction in numbersof wingless forms of aphids or of white fly nymphswhich remain on the same plant. Use of certain moderninsecticides has no doubt helped in checking the spreadof certain viruses. However, wrongly applied insecti-cides could do more harm than good. For example, ifthe viruliferous wingless forms of aphids are not killedimmediately after spraying, they will spread to theother healthier plants and they too will become infected.The manner in which the viruses are acquired and trans-mitted by the insect would also determine the choiceof the insecticide. If an insect is able to acquire thevirus quickly and is able to infect the other plantimmediately, only a persistent insect repellent or aquick-action insecticide could be effective. In the othercases a persistent type of newer insecticide wouldperhaps serve the purpose. Extermination of alterna-tive host plants of the vectors is another of the severalmeasures recommended for control of virus disease.Intensive field surveys and ecological studies of theinsects concerned would be essential prerequisites formaking this control measure effective.

INSECT PESTS OF FORESTS

The rich and valuable forests of the humid tropicalparts of South Asia are subjected to attack by a varietyof insect pests. The problems posed are too numerousto deal with here, but some of the more importantones that have been engaging attention, may be statedas illustrations. As would be expected, the researchwork adopted for their solution has been centred chieflyround the ecological, sylvicultural and biological meansof control and some of the results achieved offer valuableexamples of how some of the entomological problemscould be satisfactorily solved by these means. Thefollowing pests may be considered: Hoplocerambyxspinicornis (the sal borer), Hypsipyla robusta (theborer of toon and mahogany shoots), Hyblaea pueraand Hapalia machaeralis (the teak defoliators), andXyleutes ceramics (the beehole borer of teak).

The losses caused to sal (Shorea robusta), a veryvaluable timber in India, by the Cerambycid beetle,

Hoplocerambyx spinicomis, the larvae of which tunnelinto stem and branches, have been estimated to beabout 250,000 rupees annually from State forests alone.During epidemic years, it was estimated that in fiveforest divisions of Madhya Pradesh, the loss rose to13,700,000 rupees (or £1,044,000). A more recentepidemic in Himachal Pradesh has been described byRoonwal [331]. Ecological and physiological studiesof the borer on which the control measures are basedhave been investigated in detail. The emergence ofbeetles is influenced by preliminary monsoon showersand by the quantity of rainfall in June and July; theearlier and more abundant the rain the earlier andquicker the emergence. As the emergence of beetlescan be forecast with a fair degree of accuracy and asthe beetles are attracted to fresh sap from considerabledistances, an ingenious device of using trap-trees forthe destruction of adults has been found successful,among other means of control. Details of the successfulexecution of this device have been fully worked out.Preventive and remedial measures designed to keepthe damage below a tolerable degree include certainsylvicultural practices that do not allow the foreststo become dangerously dense.

Hypsipyla robusta, the toon and mahogany shootborer, is a serious pest of shoot6 and fruits of Cedrelatoona in North India and Upper Burma while in SouthIndia, where it bores into shoots mostly, it is foundfrom low levels to 3,000 feet. In Ceylon it is commonin plantations of Cedrela and Swietenia except at higheraltitudes, above 5,000 feet. The control of this pest hasbeen a baffling problem. It has been found that sitesfor new plantations should be free from alternativefood plants and that this factor is more importantthan climate, elevation and soil, because in the absenceof any sources of external infection, the population ofborers in young stands is rigorously limited to a fewindividuals per plant. Close spacing and an overheadcanopy of evergreens, or lateral shade given by inter-mixed plants, have been found to be useful. Biologicalcontrol by parasites has not been considered likely tobe successful, but an appreciable degree of help isobtained through predators coming from weeds andshade crops.

Hyblaea puera and Hapalia machaeralis, the teakdefoliators, are very important pests of teak (Tertonagrandis) in Burma and India. According to pre-warestimates the total annual loss due to defoliators forthe teak plantations in Burma and India were 500,000and 400,000 rupees respectively. The distribution,alternative hosts and life history of these two principaldefoliators are known, and the effect of climate factorson the length of the life cycle has been worked out invarious parts of India and Burma. Further investiga-tions have shown that crop age has a strong influenceon the incidence of defoliators in pure teak crops,although under epidemic conditions stands of all agesare equally clean stripped. The frequency of light

defoliation is at its maximum in stands of age-class21-30 years, and in the last half of the 80 years' rota-tion, light defoliation is less frequent than in the firsthalf.

Sylvicultural control may be undertaken for largeregeneration areas of teak by dividing these into partswhich are isolated by land carrying mixed tree forests.Fractions of regeneration areas are left to serve asreserves for the animal life desired in biological controlof the defoliators. These reserves may be improvedby eliminating alternative food plants and encouragingthe desirable species of plants which are attacked bysuch other caterpillars as form alternative hosts ofthe parasites of the teak defoliators. Considerableresearch has been made on the subject of the desirableplants and the insect fauna they sustain with the resultthat a list of plants is now available for use in reservesmentioned above.

Xyleutes ceramica, the beehole borer of teak, is themost important pest of teak in Burma. Its distributionranges from New Guinea to Java and the North ofBurma but it does not occur in India or Ceylon. Studies,made chiefly by Atkinson [24], Beeson [39] and Garth-waite [152], have revealed considerable details of itseconomics and nature of damage, life history andcontrol. It is estimated that as a result of the borerattack the output of teak in Burma is probably lessenedby 10-15 per cent, resulting in an annual loss of about100,000 rupees. The severity of attack of X. ceramicahas been used as an argument against further plantingof teak, but entomological researches reveal that freshplantations could be justified except in those districtswhere the incidence is high in natural forests.

Direct measures of control are impractical, but bysuitable sylvicultural practices reduction of its potentialdamage can be obtained. The incidence is correlatedwith annual rainfall: below 55 inches and at 150 inchesand above, the damage by beehole is likely to be slightto negligible. In Burma there are 12 forest divisionsin which regeneration should be permissible on thisscore. Felling in cold weather kills more borers thanif the trees are felled just before the period of emergenceof the moths. Sylvicultural practices aim at a rapidgrowth of the trees because it is believed that, whateverthe incidence of beehole, the faster the timber can begrown the less will be the material effect of any degreeof beeholing. There is also a strong possibility of improv-ing control by biological means, as has been achievedfor the teak defoliators.

The examples mentioned above are only a few ofthe many problems that exist in regard to the forestsof India, Burma and East Pakistan. In India consider-able work has been done on the basic and applied sidefor many of the pests of forests, and is being continued.In Burma, owing to the dominant claims of teak insects,the pests of other trees have received little attention,notable exceptions being the defoliators of Gmelinaand borers of Xylia and bamboos. In Ceylon the insect

pests of shade trees have been studied in considerabledetail.

INSECT PESTS OF STORED PRODUCTS

A large variety of insects infest stored products suchas grains, pulses, oil-seeds, dried fruits, timber, wool,hides and skins. The major pests are beetles and moths,and have a more cosmopolitan distribution as a resultof increased world commerce. They are too numerousto be mentioned in this short report. In tropical coun-tries, where conditions are more conducive to insectlife than in temperate countries, the losses may begreater but exact data are lacking. The problem ofassessment is a complicated one. Besides the loss inquantity due to insect attack there is also the questionof deterioration in quality resulting in taint, increasedbreakage of grains at the time of milling, or increasedacidity in certain infested oil-seeds. A detailed assess-ment of losses is, therefore, an essential prerequisitefor the proper understanding and solution of the prob-lems.

Bulk storage, which is a more economical and effectivemeans of storage than bag storage, is done in khattisor underground pits in localities where subsoil wateris low, in mud and pucka bins or bins made of strawor bamboo. Elevators, so common in America andseveral other countries, have not been tested properlyor used in India. Bag storage has the advantage ofbeing conveniently handled, quickly transported andeasily segregated from infested stock. However, gunnieseasily pick up infestation and the inter-bag air spacespermit rapid multiplication of pests and easy accessfor rats, etc.

The effects of airtight storage on grains and pestshave not been investigated thoroughly under tropicalconditions and conflicting views continue to be heldon the efficacy of this method of storage. Cotes [83]was the first among entomologists in India to advocateairtight storage of grain. The subject is now beingpursued elsewhere [180, 300] and large-scale trials arebeing conducted in tropical Africa on the auto-sterili-zation of insect-infested grain in specially constructedpits in the soil. The investigations require knowledgeof the movement of heat and moisture through grainand of the physical condition of the grain when putinto store, with special reference to the influence oflocal climate. Similarly, knowledge of the respirationrates of grain and insects would also be required torecord the rate of build-up of carbon dioxide, whichis lethal to insects. Plywood silos, besides being cheaper,are stated to overcome the problem of condensationthat arises in the case of metal, concrete and bricksilos; if, as suggested by Hall [180] under tropicalconditions damp grain (i.e., about 14 per cent moisturecontent) could be stored safely in hermetically sealedstructures, a great problem in grain storage will havebeen solved.

The importance of the storage of rice is being graduallyrealized. Burma, with its usually surplus rice production,is likely to benefit most from investigations on thissubject. Specific investigations are also required tobe made into storage of pulses, oil-seeds, copra, driedfruits, wool and woollen materials, furs, leather, hornsand bones, etc. ; these have received much less attentionthan the problem of stored grains.

Very little is known about the distribution andecology of the pests of wool in the various hilly tractsof the countries of South Asia. Their study deservesspecial attention. Research on insect damage to timberafter it has been sold and put to commercial use hasbeen carried out at the Forest Research Institute andalthough the broad principles of control are known,the new problems arising from the increasing industria-lization of India need special attention [39]. In spiteof their importance, basic research on the pests ofdifferent stored products and storage problems inhumid tropical parts of South Asia has hardly beenundertaken as yet.

MEDICAL ENTOMOLOGY

There is a brilliant record of research made in Indiaon insects of medical importance. Following the epoch-making discovery of Ross in 1898 on the role of mos-quitoes in the transmission of malaria, and also becauseof the importance of the disease in India, a great dealof valuable work was carried out on mosquitoes parti-cularly by Stephens, Christophers, James and Liston.Further discoveries on insect transmission of plague,relapsing fever, Kala-azar and guinea worm were alsomade. Other well-known diseases involving the agencyof insects, ticks and mites are filaria, oriental sore,sandfly fever, typhoid fever, cholera, summer andinfantile diarrhoea, dysentry, myiasis, endemic typhus,scrub typhus, etc.

It would not be possible in a brief report like thisto review all the numerous problems of medical ento-mology in South Asia. The United Nations WorldHealth Organization has been active in these andneighbouring regions in executing anti-malarial mea-sures with considerable success, and in many partsmalaria has been brought under control: use has beenmade of the accumulated knowledge of the life history,ecology, habits and behaviour of the various speciesof mosquitoes, as also of the modern insecticides, likeDDT and BHC.

A few basic aspects of medical entomology may bementioned.

Survey, classification and ecological studies. Studies ofinsects and other arthropods of medical importanceneed to be intensively pursued and the gaps in ourknowledge of the ecology, etc., of the known andpotential carriers of diseases filled up. As the well-known entomologist Howard [190] rightly pointed out,

Problems of humid tropical régions/Problèmes des régions tropicales humide

there is need for a study of all insects of medical impor-tance without an eye for immediate results, so thatwe may discover all about them and then apply ourknowledge for their control. Work on mosquitoesprovides a model. Reports on mosquito surveys inIndia, most of them lying in office files of the publichealth departments of various provinces, were cata-logued by Sinton [360]. Covell [84, 86] published me-moirs on the distribution of Anophilines in India andCeylon. Anophiline and Culicine mosquitoes have alsobeen mapped. Some work on these lines has also beenproduced on certain fleas, flies, sandflies and humanlice. However, much more remains to be done on thesegroups as also on ticks and mites, for the taxonomicstudies of which there are hardly any specialists work-ing in South Asia. Moreover, with the advance of ourknowledge of the principles of systematics some of theolder classifications would need revision. Differentsubspecies and biological races may bear differentrelationships to a disease. Rao, Sweet et al [321] have,for example, distinguished Anopheles stephensi intotwo races on the evidence of size of egg, wing lengthsand character of offspring and have suggested thatthere may be a difference in their malaria-carryingpotentiality. Others, like Roy [335], have not beenable to support this suggestion. This and similar prob-lems that have or are likely to crop up as a resultof further systematic studies would require furtherinvestigation.

Resistant strains. Related closely with the studies ofspecies, subspecies and races found in nature is thequestion of the evolution of varieties or strains resistantto insecticides. The DDT-resistant houseflies werefirst observed in 1946 in certain parts of Italy whereDDT had been applied since 1944. In subsequent yearsthe same phenomenon was observed in several differentparts of the world. Resistance to BHC was likewisediscovered both in the New and Old World and thereis a real apprehension of the same being observed inSouth Asia in due course. The genetics and physiologyof resistance have been studied intensively in America.DDT-resistant strains have been produced experiment-ally in the laboratory and it has been found that stockswhich are in process of developing resistance to DDTare also generally becoming resistant to other insecti-cides like methoxychlor and DDD. At further stagesof development they become resistant to lindane,chlordane, dieldrin and toxaphane, etc. Moreover, theresistance is stated to be maintained for several gene-rations in the progeny bred free of an insecticide.Researches into the genetical behaviour have yieldeduseful results for a proper understanding of the pheno-menon. Resistance may also result in change of beha-viour, as has been noted for several species in Amer-ica—for example resistant flies may rest more on thefloor than on walls and ceilings which are usuallysprayed. They may have a longer larval period than in

the case of susceptible flies. Investigations have alsobeen made into the factors responsible for this beha-viour. It is desirable to make similar studies on thelocal species under tropical conditions of SouthAsia.

Quarantine. Fear of yellow fever is real in India. Ifby any chance the disease enters this country thedanger will be all the greater on account of the widedistribution of Aedes eagypti, the Indian strain of whichis as infective to yellow fever as the African strain. Thetwo common monkeys of India, Silenus rhesus andS. sinicus, are susceptible to the virus of yellow feverand would serve as reservoirs for the disease. Man-sonioides uniformis, which is widely distributed inIndia and bites man freely as also certain other speciesof Aedes, are capable of transmitting the disease.Climatic conditions also increase the danger. Severalquarantine measures are taken by the Government,of which one of the important ones is sanitary or"anti-amaryl" aerodromes. Powerful organic spraysare used to disinfect aeroplanes. All sorts of insects,including those of medical importance, may be foundin the aircraft and it is usually the staff of the airport'shealth officer who collect them. As far as is known,there is no special organization in Calcutta or otherports of India with an entomologist for identifying,preserving and recording the collections thus made.Besides being of practical value from the point ofapplied entomology, such records could throw light onthe dispersal of insects, especially on the role of upper-air currents.

VETERINARY ENTOMOLOGY

A good proportion of mortality and disease amongcattle in the tropics is attributed to arthropodal inva-sions. On account of the large numbers of cattle andother livestock in South Asia and the important rolethey play in the agricultural economy, the subject ofveterinary entomology assumes a special significance.However, until very recently (1933) no specializedagency for research on veterinary entomology existedin India and the work—of an exploratory nature—hadbeen largely incidental to other activities of the vete-rinary, medical and agricultural departments. Anentomologist was first appointed at the Indian Veteri-nary Research Institute in 1933.

The more important of the veterinary pests belongto arthropods—insects, ticks and mites—which arespecially adapted for life as parasites on warm bloodedanimals. The gadflies of the female sex only feed onthe blood of cattle, the commonest form in tropicalIndia being Tabanus striatus and Chrysops dispar. Inthe forests and hilly tracts, forms like Haematopotaand Pangonia are also encountered. P. taprobane hasa very long and peircing type of proboscis with whichit is said to attack the skins of wild elephants and

bisous. The horse flies of the species Hippobosca maculataand H. capensis cling to and attack cattle, horses, dogs,etc., while a wingless form, Melophagus ovanus, isknown to attack sheep in different parts of India. Thebot flies cause damage as internal or subcutaneousparasites of hosts, the important types beings (a) thehorse bot fly (Gastrophilus equii) found mostly inNorth India; (b) the sheep bot fly (Oestrus ovis); and(c) the ox bot flies or warble flies (the chief Indian formbeing Hypoderma lineatura). Though widely distributedin North India, the latter are not very common in theSouth. The warbles on the body make the ox, cow orgoat lose condition and become unhealthy and inmilch cattle milk production is greatly reduced. Thehides and skins of infected cattle show warble spots,a serious defect in the trade, causing an annual lossof several lakhs of rupees.

The larvae of the bluebottle, Lucilia serenissima,are generally found on exposed flesh or in wounds andsores on cattle and may cause other cutaneous diseases.The flesh flies, chiefly Sarcophaga lineaticollis, areassociated with bluebottle flies and cause similardamage. The biting flies include the stable fly, Stomoxyscalcitrans, which has a cosmopolitan distribution andfrequents cowsheds and stables.

The bird lice (Mallophaga) of poultry belongs to thecosmopolitan species Menopon pallidum. The commonestspecies of blood-sucking lice is the buffalo louse, Haema -topinus tuberculatus, found in protected parts of buffaloesand oxen.

Ticks and mites (Acarina) are of special importancein veterinary entomology, as most of these creaturesare ectoparasites of higher animals and some also actas vectors of several serious diseases. Some of thecommon ticks occurring in India are Boophilus australis,Rhipirephalus sanguineus, R. haemaphysaloides, Hya-lomma aegyptium and Haemaphysalis bispinosa. Thecommon mite, Psoroptes commuais, is responsible formange in horses, cattle, sheep and rabbits.

Transmission of animal diseases. Surra, being a chronicdisease of cattle and fatal to the horse, mule, etc.,received early attention, when Rogers tested thepossibility of Tabanus flies being involved as vectors.Several workers subsequently investigated the sameproblems, Basu [35] being the most recent among themto confirm earlier results. The canine tick fever wasstudied by Christophers [79] and Shortt (1937) whoincriminated the ticks R. Sanguineus and Haemaphy-selis bispinosa as the vectors. Similarly, work has beendone on the transmission of chicken cholera and onfowl spirochaetosis through the tick Argas periscus.

The possibility of arthropod transmission of rinder-pest has been investigated by a number of workersincluding Bhatia [43] and Kapur [216], who succeededin transmitting it through Tabanus orientalis. Senand Minett likewise succeeded in transmitting anthraxthrough Musca domestica, while Basu [35] obtained

similar results with M. nebulo, and H. aegypticum.

Survey of insects and acarids of veterinary importance.There is not enough information on the occurrence anddistribution of arthropod vectors of several importantdiseases and of other insects, ticks and mites of veteri-nary importance in India, Burma, etc., which is basedon detailed surveys and accurate identifications. Ina few cases, where recent surveys have been carriedout by the staff of the Veterinary Research Instituteand other officers of veterinary departments, it hasbeen observed that the pests are distributed over muchwider areas in India than had been previously thought.Hypoderma lineatum and H. crossi (ox and goat warbleflies), which have been specially investigated under ascheme sanctioned by the Indian Council of Agricul-tural Research, are examples. Systematic and zoo-geographical studies of ticks and mites and of certaingroups of diptera of veterinary importance are required.

SYSTEMATIC ENTOMOLOGY

One of the foremost fundamental entomological prob-lems in the countries of South Asia relates to thestudy of insect taxonomy or systematics. The namesof the different insects must be known in order thatfull use is made of the literature on them. A recentestimate puts the number of known species of insectsin India, Burma and Ceylon at over 40,000 and statesthat an equal number had probably not been described(Gardner in [49]). A great deal therefore remains tobe accomplished in this branch of entomology. Onaccount of the vastness of the subject the progress sofar made cannot be adequately reviewed in a shortreport like this. However, a few important works oncertain major orders of insects may be mentioned.

Lepidoptera. There is an extensive literature on butter-flies especially by earlier workers like Wood-Mason [374,375], Moore [268, 270], Swinhoe [362, 363], Watson [371],de Niceville [282-7] and Marshall [260], Bingham [45,46] published two volumes on butterflies in the Faunaof British India including Burma and Ceylon series. In1939 and 1947, Talbot published two volumes in thesame series (lately called Fauna of India), revisingBingham's work. Moore [269] and Ormiston [297]published an account of the butterflies of Ceylon.In 1927 Evans [113] wrote a book on the identificationof butterflies of India, Burma and Ceylon. In 1942,Woodhouse monographed the butterfly fauna of Ceylonof which a second edition has appeared [372, 373].

Hampson [181-4] contributed four volumes on Indianmoths in the Fauna series. Bell and Scott [42] contributedthe fifth volume on hawk moths in the same series.Other notable contributions were made by Moore [269],Moore Swinhoe (loc. cit.), Dudgeon [103-8], Meyrick[267] and Fletcher [117-26], the last two being speciallydevoted to Microlepidoptera. Kapur [214] has mono-

graphed] Crambine moths associated with sugar canein India.

Coleóptera. There are some 18 volumes devoted toColeóptera in the Fauna series. Gahan [144] producedone on Cerambycidae, Jacoby [201] a volume on thefirst nine subfamilies of Chrysomelidae, and Maulik[264-6] a further three volumes on the latter family.Arrow [14, 15, 17] also wrote three volumes on Lamelli-cornia and one [16] on Erotylidae, Languridae andEndomychidae. Fowler [127] wrote a volume as anintroduction to Coleóptera, and Marshall [257] publisheda volume on Curculionidae in the same series. Twovolumes on Carabidae were written by Andrewes[4, 6] and four on Staphylinidae by Cameron [59-62].The same authors as well as several others includingBalfour-Browne, Blair, Bryant, Corporaal, Dover,Gardner, Gilmour and Dibb, Hinton, Kapur, Ochs, etc.,have made further contributions in scientific periodi-cals. Special mention may be made of Gravely's [160-2]contributions on Tenebrionidae, Cucujidae and Lycidaeof India and Burma and on the Passalidae of the world.

Hymenoptera. Wood-Mason [374, 375] and Forel (1885-1902) were early workers on Indian Hymenoptera.Bingham [45, 46] produced two volumes in the Faunaseries, the first on wasps and bees and the second onants and cuckoo-wasps. Morley [271] contributed thethird volume on Ichneumonids in the sames series.Among other important contributions, those by Rohwer(1915), Malaise [244], Muesebeck [277], Mani [245, 255]may be mentioned. Donisthorpe [101, 102] studied theants of Southern India.

Diptera. By 1900 mosquitoes as vectors of malariahad been conclusively implicated and in the same yearGiles produced a paper on mosquitoes. Christophers[80] and Barraud [34] produced two volumes on Culi-cidae in the Fauna series. In 1905 Christophers wrotea memoir using larval character in the classification ofmosquitoes, and later Strickland and Choudhury (1927)and Puri (1932, 1933, 1941) wrote on the same subject.Further systematic studies on the mosquitoes of Ceylonwere made by Edward (1914-29) and Carter (1925).Brunetti [52-4] contributed three volumes in the Faunaseries, on Nematocera, Brachycera and the familiesPipuculidae, Conopidae and Osteridae. Senior-White,Aubertin and Smart [344] contributed another volumeon Calliphoridae. Sandflies or Psychodidae have beenfurther studied by Sinton [358-60], Tonnoir (1933)and Theodor [366]. Awati (1914), Patton and Senior-White [302] have studied muscoid flies, while Puri(1932) studied the Simulidae. Bezzi (1913) and Munro[274, 275] monographed fruit flies (Trypetidae). The gallmidges or Itonididae have been studied by Mani[245, 248] and Tipulidae by Alexander [1, 2].

Hemiptera. Aitken (1884-89) and Kirkcaldy and Ker-

shaw (1909) are among the earlier workers on Hemip-tera. Distant [94-100] contributed six volumes in theFauna series while Green's (1899-1919) valuable contri-butions, The Coccidae of Ceylon, is a landmark in thestudies of this order. Das [89] has worked on Aphididae,Pruthi [307-9] on Jassidae and Singh [357] on Aleuro-didae.

Orthoptera. Wood-Mason [374,375] worked on Phasmidae(leaf and stick insects) and Mantidae (praying insects),while Kirby [229] wrote a volume in the Fauna series,on the Acrididae. Contributions on the latter familyhave also been made by Uvarov (1927-42).

Miscellaneous orders. Siphonaptera or fleas of India,Burma and Ceylon have been studied chiefly by Crag(1923), Sharif [346], Sinton (1925), Hirst (1914, 1923-33), Jordon and N. C. Rothschild (1920) and M. Roths-child (1940). Anoplur and Mallophaga (lice) have beenstudied by Kellog and Paine (1914), Cadri (1933, 1936),Clay (1940), Ansari (1944, 1947, 1951) and Roonwaland Natraj [334].

Burr [57] contributed a volume on Dermaptera inthe Fauna series. Thysanoptera have been studied byBagnai (1912), Ayyar and Margabandhu [29, 30],Moulton (1929), Shamsher Singh (1942-46) and others.Isoptera were studied by Wasmann in 1889, and laterby Asmuth (1913), Holmgren (1917), Silvestri [352, 353],Jepson [205, 206], Kemner [217], Snyder (1949), andRoonwal (1953).

Odoneta or dragonflies have been studied by Laidlaw[232, 233], Needham[281] and Fraser [129-31], who hascontributed three volumes in the Fauna series. Lieft-nick (1940) has dealt with the dragonflies of Ceylon.Ephemeroptera (mayflies) have been studied by Gra-vely (1920), Chopra [78], Hafiz [176], Traver (1939)and Kimmins (1947) while Trichoptera (caddis flies)have received the attention of Martynov (1935, 1936)and Moseley [272]. A certain amount of work has alsobeen done on smaller orders like Collembolla, Thy-sanura, Embioptera, Psocoptera and Neuroptera.

Important though these contributions by earlyworkers on the systematics of Indian insects have been,much remains to be done in this branch of entomology,especially in the light of modern conceptions andknowledge of the subject.

CONCLUSIONS

Even a brief perusal of the history of entomologicalresearch in South Asia and in other parts of the worldwill show how constant and how arduous has been thestruggle between insects and man. Entomologicalproblems are mostly dynamic. Unfortunately, in solvingcertain problems man, through his ignorance or underforce of circumstances, has created other problems. Thereis indeed evidence to show that losses from insects have

increased, during recent decades. It often happensthat a step forward in civilization is also a step favour-able to one insect or another. Progress in transportfacilities such as ships, motorcars, railways and aero-planes, help in spreading insect pests. On account ofincreased means of transport there is a real fear of theapproach of yellow fever from America and Africa intotropical Asia where the mosquito vector as well as thewild, potential, reservoir for the virus in rhesus monkeyare present. To check the spread of disease and pestsinto their territories, quarantine measures are enforcedfay various countries. The methods we employ toproduce more food and store it in large quantities havealso helped in the rapid spread of certain pests. In-creased cultivation of sugar-cane since 1930 has givenrise to the Pyrilla problem.

A more recent problem relates to the modern organicinsecticides, which are being used, sometimes indiscri-minately, for the destruction of certain pests. Leavingaside the largely undecided question of production ofresistant strains of insects, there is no doubt thatnatural insect enemies of major pests as well as ofother insects which are not so destructive, are alsokilled by these insecticides. Observation on the brinjalmealy bug, Phenococcus insolitus, and Aphis fabae inWest Bengal showed that "in fields where DDT andBHC were used a damaging infestation of a secondgeneration of the pest was found to have developed"after the annihilation of the Coccinellid predator,Hyperaspis maindroni [70]. There are several instancessuch as insect pests of tea where certain insects andmites which were not considered earlier to be of muchimportance have come into prominence as major pestspartly because their natural insect enemies, which hadhitherto regulated them, have been substantiallyreduced by powerful insecticides and partly becausesuch insecticides are not good acaricides. Anotheraspect of the same problem, for which instructiveinstances have lately come from Ceylon, relates to thespreading of certain pests consequent upon the applica-tion of such insecticides. Since the inception of insecti-cidal treatments in 1949, the incidence of egg para-sitization of the paddy pentatomid bug, Scutinophoralurida, has been progressively decreasing so that whereasin 1941 the parasitization of the eggs was 89 per centit was nil in 1954. It was further reported that whilein the past the bug occurred in Ceylon as a pest ofpaddy in the Ambalantota area only, in 1954 it wasappearing in increasing numbers in several other pro-vinces and that there was a fear of its becoming amajor pest of paddy on a much more extensive areain the island than at present [115]. Thus new problemscontinue to arise, and the desirability of a discreeteruse of insecticides is becoming more widely recognized.At present in South Asia the use of insecticides is notquite so widespread as in certain Western countries,where the need for control by more remunerativemethods of biology is once again being emphasized.

In South Asia, we may take advantage of their expe-rience before similar problems arise on a large scale inour countries. We should also devote as much attentionas possible to control measures by ecological and biolo-gical (in a wider sense) means.

A proper approach to entomological problemsdemands that a thorough study of the insect itselfshould be undertaken before embarking on controlmeasures against it in the field. This involves:1. A correct identification of the insect in the first

place so that full use is made of the informationabout it to be found in the literature.

2. A study of the life history and habits, relation toclimatic conditions, population estimation anddamage assessment, alternative host plants, naturalenemies and relation of the pest to cultural practices.

3. If the study under (2) suggests chemical control,laboratory tests with suitable insecticides followedby small, properly laid out, field trials should beundertaken. If on the other hand, the study suggeststhe application of cultural, ecological or (in a broadsense) biological measures, these may be followed.In each case the ideal is to study constantly all theimplications of the measures undertaken on thebiology of the pest, as well as on the predators,parasites and other minor pests. In the light ofthese observations it may be possible to foreseenew problems that may arise in the areas concer-ned.

The progress made in many fields of entomologicalresearch in South Asia during the last 50 years or morehas been impressive. In several other fields considerableadvance has been made, but a lot remains to be done.The following aspects of entomological research deservespecial consideration:

Systematic entomology. It has been repeatedly pointedout by Hussain [191], Ayyar [27] and Roonwal [329,332] that studies in systematic entomology in India(and this equally applies to other parts of South Asia)deserve special attention. In the words of Roonwal[332]: "Our greatest weakness is in the field of entomo-logical systematics, that is to say, the authentic identi-fication of adult insects and also of immature stages,and the provision of suitable keys and monographs. . . .There are three main centres of systematic research,in India, viz. the Zoological Survey of India, Calcutta,the Indian Agricultural Research Institute, New Delhi,and the Forest Research Institute, Dehra Dun . . . butthe combined resources of all these institutions, bothin manpower and in insect collections, are extremelyinadequate considering the vast insect wealth of Indiaand the great problems that confront us in their syste-matic study." In Ceylon, the Colombo Museum is thecentre of systematic study. Fortunately in this fieldof study much progress can be made both throughinternational co-operation and through national efforts.A good reference collection and library and trained

workers are the main requirements for systematicstudies. In modern times these studies require thewhole-time attention of technically trained workers,and the answer to this problem in South Asia clearlylies in the employment of more workers at institutionsequipped for this kind of work. It is to be hoped thata Bureau of Systematic Entomology for South Asia maybe set up under the auspices of Unesco to meet therequirements of this region, especially for the produc-tion of monographs, keys and catalogues on insects ofthe Indian sub-region.

Insect ecology and physiology. Animal ecology has beencalled the real foundation of applied zoology. We haveobserved how some of the foremost entomologicalproblems in the forests of India and Burma have beensatisfactorily solved by ecological (including sylvicul-tural) methods of control. In agriculture also, muchof the progress made in the solution of locust andcotton bollworm problems has been achieved by inten-sive ecological studies. The influence of weather onpest outbreaks is of prime importance. Epidemics ofthe army worm (Spodoptera mauritia) on paddy, ofblack-headed caterpillar (Nephantis serinopa) on coco-nut palms, of Pyrilla on sugar-cane, of the hairy cater-pillar (Diacrisia oblique) and the jute semilooper (Anomissobulifera) on jute and of the looper caterpillar (Bistonsuppressaria) on tea, and several other pests have

been mentioned: any scheme that would forecast theoutbreaks of such pests would be greatly appreciatedby farmers and planters alike. Investigations on therelationship between plants, insects, climates, seasonsand distribution may give a clue to the factors respon-sible for rapid multiplication and epidemic outbreaksof pests and may eventually lead to the adoption ofmeasures to prevent the occurrence of such outbreaks.However, if the interrelation of an insect and its environ-ment is to be correctly understood, a proper knowledgeof the physiology of the insect must be acquired, sincethe response of the insect to a certain stimulus is likelyto vary from species to species. Thus from the pointof view of economic entomology, insect physiologydeserves to be studied as closely as insect ecology.

Pest infestation of stored products. Stored productsunder humid tropical conditions in South Asia aresubject to serious losses as a result of pest infestation.Stored grains are of major importance and of these,stored rice deserves special attention in tropical coun-tries. Special investigations on pulses, oil-seeds, copra,dried fruits, wool and woollen materials, furs, leather,horns and bones, timber and other forest products arealso required. A central laboratory or institute withseveral centres of research suitably located in differentparts of the region is urgently needed.

Rapport sur les problèmes entomologiquesdes régions tropicales humides

de l'Asie du Sudpar

le Dr A.P. Kapur

Résumé

II existe dans les régions tropicales humides de l'Asiedu Sud de très nombreux végétaux, mais ce rapportne traite que des principaux problèmes entomologiquesqui intéressent le paddy, la canne à sucre, le jute, lecocotier, le thé et le caféier. L'arbre à caoutchouc,heureusement, n'est guère attaqué par les insectes;

nous ne nous en occuperons donc pas. Nous laisseronségalement de côté certaines autres cultures, dontl'importance économique est moindre.

Les riches forêts des régions tropicales humides del'Asie du Sud sont attaquées par diverses sortes d'insec-tes. Comme on pouvait s'y attendre, les recherches

entreprises pour les résoudre ont porté surtout sur lesmesures relevant de l'écologie, de la sylviculture et dela biologie; certains des résultats obtenus sont particu-lièrement intéressants en ce qu'ils montrent commentquelques-uns des problèmes entomologiques les plusdifficiles pourraient être résolus par l'application deces mesures.

De très nombreuses espèces d'insectes s'attaquentaux produits mis en stock, tels que céréales, légumi-neuses, graines oléagineuses, fruits sécbés, bois, laine,cuirs et peaux. Les plus malfaisants sont des coléoptèreset des noctuelles, dont la répartition est devenue pluscosmopolite par suite du développement du commercemondial. Dans les pays tropicaux, qui offrent au déve-loppement des insectes des conditions plus favorablesque les pays tempérés, il est fort possible que les pertessoient plus importantes que dans ceux-ci; mais onmanque des données nécessaires pour en calculer lemontant exact. Outre les pertes quantitatives dues auxravages des insectes, il y a la diminution de la qualitédu produit. Une évaluation précise des pertes cons-titue une condition indispensable à la compréhen-sion correcte de ces problèmes et à leur solution.

II est nécessaire de poursuivre de façon intensive lesenquêtes, les classements et les études écologiques surles insectes et autres arthropodes d'importance médi-cale, et de combler les lacunes de nos connaissances surl'écologie et autres caractères des vecteurs de maladies,connus et possibles.

L'un des plus importants problèmes d'entomologiefondamentale qui se posent dans les pays de l'Asie duSud a trait à la taxonomie des insectes ou entomologiesystématique. Le nombre des espèces connues d'insecteshabitant l'Inde, la Birmanie et Ceylan a été évaluérécemment à plus de 40 000, et l'on estime qu'il enexiste très probablement un nombre égal qui n'ont pasété décrites.

Des progrès considérables ont été faits depuis unecinquantaine d'années en Asie du Sud dans de nombreuxdomaines de la recherche entomologique. Dans plu-sieurs autres domaines, les progrès ont été notables,mais il reste encore beaucoup à faire. Les aspects ci-après de la recherche entomologique méritent de retenirtout particulièrement l'attention : entomologie systé-matique, écologie et physiologie entomiques et dégâtscausés par les insectes aux stocks.

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3. ANANTNARYANAN, K. P. "On the bionomics of an Eulo-phid (Tricosphilus pupívora Ferr.), a natural enemy ofthe coconut caterpillar Nephantis serinopa", Bull. ent.Res. 1934, vol. 25, p. 55-61.

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13. ; KEMP, S. "Fauna of the Chilka Lake—aquaticinsects, other than Coleóptera, with notes on somemarginal species", Mem. Indian Mus. 1915, vol. 5,p. 175-189.

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15. . ibid. Pt. 2: "Retulinae, Desmonycinae, Euchri-nae". London, 1917, p. 1-387.

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17. . ibid. Pt. 3: "Coprinae". London, 1931, p. 1-428.18. . "Some notes on stag beetles (Lucanidae) and

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Problems of the Humid TropicalPhilippines with special reference to

Water Resources Developmentby

Hon. Filemon G. Rodriguez,President and General Manager, Engineering and Development Corporation

of the Philippines, Manila.

This paper reports on the problems of the Philippinesas a humid tropical area, particularly in relation towater resource development and its specialized compo-nent aspects of irrigation, hydro-electric power gene-ration, soil conservation, water supply, flood control,etc., and also on the research work being undertakenwith respect to these problems.

GENERAL PHYSICAL AND SOCIO-ECONOMIC CONDITIONS

LOCATION AND CLIMATE

The Philippines are an archipelago of about 7,110islands lying between the equator and latitude 22° N.and between the 116° and 127° meridians east ofGreenwich.

The air temperature of the islands averages about80° to 82° F. with a maximum range of 50° to 101° F.In most of the populated areas the range is actuallymuch narrower, in general between 70° and 100° F.Relative humidity is generally high, with an annualmean value of about 80 to 85 per cent.

The annual average rainfall rate is 93 inches, basedon long records of observation at 53 rainfall stationsdistributed throughout the country. The lowest annualrate was 42.8 inches in Zamboanga and the highest176.7 inches in Baguio. The heaviest 24-hour rate waslikewise registered in Baguio when 47.6 inches fellduring the typhoon of 14-17 July 1911. On the basisof the criteria used by Gourou,1 the Philippines fallwell within the classification "warm and rainy tropicalregions".

The rainfall is indeed sufficient to enable muchagriculture to be pursued without irrigation. Whileirrigation is recognized as desirable in order to make

increased production possible throughout the year, itis not an absolute prerequisite to production.

Owing to the subdivision of the 114,400 squaremiles of land area of the country among so many islandsand the bold relief of some of the islands, there are fourdistinct types of climate found in the country. Fig. 9indicates the areas where each type prevails and brieflydescribes each. The appendix on the climate of thePhilippines gives details of the climatic types, aircurrents, and storms.

POPULATION

As of 1 July 1955, the population of the Philippineswas estimated at 21.4 millions, giving an overall den-sity of about 187 per square mile. The annual rate ofpopulation increase is estimated at 1.91 per cent.Between 70 and 75 per cent of the total populationis believed to be outside the urban areas. The labourforce numbers about 8.3 million or 39 per cent.

ECONOMIC AND SOCIAL CONDITIONS

The Philippines is mainly an agricultural country,agriculture contributing over 40 per cent of the nationalincome and employing over 70 per cent of the labourforce. Manufacturing contributes only about 14 per centto national income and employs less than 7 per centof the labour force.

National income per capita was about 360 pesos in1955 (equivalent to about U.S. $180 at the official rateof exchange). The level of consumption is rather high,being 94 per cent of national income, and domesticinvestment (net of capital consumption allowances)is less than 4 per cent. Yearly growth in real nationalincome per capita is estimated at slightly over 3 per cent.Available statistics on unemployment, although not

1. Unesco NS/HÏ/3, 24 February 1955.

Problems of the humid tropical Philippines

of a high degree of reliability, indicate that it is quitesubstantial, the estimates varying from 1.3 millionto 2 million or from 15 per cent to nearly 25 per centof the labour force. In addition, there is known to bequite a degree of under-employment and disguisedunemployment in agriculture.

Farming and fishing methods are still largely pri-mitive. Mechanization, the use of fertilizers, bettervarieties, and improved techniques, and scientificcontrol of pests and diseases have barely been started.Irrigation is gradually being intensified and agriculturalresearch pursued more extensively.

The main crops are rice, corn, and root crops fordomestic consumption and coconut, sugar, abaca, andforest products for export.

Industrialization is increasing and efforts are beingmade to improve the inefficient methods of transporta-tion and distribution. The direction of long-term im-provement of the economy appears to lie in the increasingindustrial utilization of the country's rich mineral,forest, water and marine resources.

Owing to increased activity in the past few yearsin the improvement of sanitary and living conditionsin the rural as well as in the urban areas, health andsocial conditions have improved, the death rate hasbeen lowered, and more communities are being providedwith water and other services.

With education and law and other conditions gra-dually improving the socio-economic outlookis promising

PHILIPPINE PROBLEMS WITH SPECIAL.REFERENCE TO WATER RESOURCESDEVELOPMENT

GENERAL

Water resources development in general can proceedonly in an orderly manner and at necessary speed ifthe needs for development are clearly defined, sufficientand reliable hydrologie and geologic data are available,and funds and trained personnel are available for devel-opment.

The needs for development of the water resourcesof the Philippines cover power generation, irrigation,water supply, domestic and industrial, and fisheries.

Methods of control, as distinguished from the utili-zation, of water resources require development asregards soil erosion and conservation, flood controland drainage, pollution abatement, and domestic andindustrial sewage treatment.

The funds needed for development are substantialand—considering that the Philippines is an under-developed country with all the poverty in capitalresources such a condition connotes—are difficult toobtain, though of vital importance. Trained personnel,on the other hand, is not a fundamental problem.The country has a supply of them and of training

facilities at hand. Whatever additions to both personneland training facilities may be needed can be easilyprocured from external sources. Finance and personnelare, however, beyond the scope of this paper.

In the matter of hydro-electric power development,the need for expansion is evident—per capita powergeneration is barely 35 kWh. and installed per capitacapacity barely 10 watts. These low levels act as anobstacle to faster industrial development. There isclear need for at least a doubling of hydro-electriccapacity and output in the next five years.

As regards irrigation, only about 11 per cent of thecultivated area is irrigated. By far the greater portionof the irrigated area is devoted to underwater ricecultivation and, in the greater part of this, irrigationis merely supplementary to the rainfall available duringthe planting of the rainy season crop. Over 100 millionpesos (U.S. $50 million) in government funds is atpresent earmarked for construction and expansion ofirrigation systems.

The needs for water supply, domestic and industrial,are indicated by the fact that barely 35 per cent ofthe 1,200 cities, municipalities, and municipal districtsn the Philippines are provided with piped water sup-plies, and most of these are inefficient, obsolescent andinadequate. The rest obtain their supplies from indi-vidual wells, springs, creeks, or by direct collectionof rain water. To provide the areas at present unservedby individual sanitary wells, it is estimated that about52,000 wells will have to be constructed in the next5 to 10 years, on the basis of one well for every 250 per-sons.

Navigational needs are limited to routine mainte-nance of roadsteads and docking and loading facilitiesand hence need not be considered further in this paper.

Fisheries, both marine and fresh water, need to bedeveloped in order that the national dietary levelsmay be brought up to minimum standards, especiallyin the matter of proteins which the very limited animalproduction capacity of the country cannot supply formany years to come.

As to water control, the most urgent need is forsystematic and sustained soil conservation and erosioncontrol. Much of the forest cover is being destroyedby unscientific logging practices including the pri-mitive farming method of burning out an area to plantroot crops or highland rice or corn—as still practisedby some aborigines.

Next in importance is flood control and drainage,the need for which is greatest in some of the urbanareas, such as Manila and its suburbs. Similarly, theneed for pollution abatement and domestic and indus-trial waste treatment is limited to urban areas and afew localities where mine tailings have become a prob-lem. Industrial waste treatment and disposal are notyet of primary importance but, as industrial develop-ment continues they will become an urgent problemin the industrial areas.

The availability of hydrologie and geologic data isintimately connected with the problems discussedhereunder.

WATER RESOURCES DEVELOPMENT PROBLEMS IN

GENERAL

In considering the problems related to water resourcesdevelopment, there are those which inherently arecommon and of general applicability to most, if notall, fields covered by the subject. These are brieflypresented as a preliminary to more detailed discussionof those related to specific fields of water resourcesdevelopment.

Deficiencies in Basic Hydrologie Data

The need for adequate hydrologie data in water resourcesdevelopment is fundamental. Inadequate water studiesdue to insufficient data could result in failures, eitherdue to the deficiency of water or in unforeseen hydraulicphenomena that may lead to the collapse of hydraulicstructures. Lack of data could mean deferment ofprojects even if the need for them is urgent.

In the Philippines, there is a sad lack of hydrologiedata for many regions and islands. There are rainfallstations scattered all over the archipelago, but thenumber for the total area covered is inadequate, andeven then, except for a few stations, only total day-to-day records of precipitation are kept. Short perioddistribution of precipitation, from which intensity-duration relations can be derived for purposes of floodanalysis, are unavailable for most of the critical areas.

Stream flow data for some major rivers have beencollected, but records are discontinuous in many cases.Most of the gauging stations are located at the lowerreaches of rivers where, unfortunately, diversion sitesfor irrigation, water supply, and water power develop-ment are less favourable. Many streams with apparentlygreat potential value have not been gauged at all.

Data on evaporation, evapo-transpiration, infiltra-tion and interception needed in the evaluation ofwater losses are few and unimportant. Lack of groundwater data prevents the optimum use of this potentialsource, which could alleviate the recurrent shortageof water during the dry season. Indiscriminate uses aswell as reduction of forest cover in intake areas havealready resulted in serious localized depletion of groundwater supplies in some areas, and point to the needof improving and extending the water rights laws tocover the uses of ground water which are now beyondtheir regulatory scope.

There is not only a need for competent observers toundertake the collection of much needed hydrologiedata, adequate instruments and equipment, and tech-nical personnel with sufficient relevant experience andcompetence to analyse and interpret these data arealso necessary.

Problems related to Storage Development

The climate map of the Philippines (Fig. 9) shows theareas characterized by markedly dry and wet seasonswhere streams are a mere trickle in summer and over-flow their banks during the rainy season. In theseareas, which include the densely populated and welldeveloped regions on Luzon and the Visayas, streamsare of negligible utilitarian value unless storage isprovided. Full development of the water resourcesrequires large reservoirs adequate to regulate streamflow on a seasonal basis. Owing to topographic condi-tions, creation of reservoirs generally involves theconstruction of high dams, with problems necessarilymuch greater in magnitude and complexity than inpurely diversion structures.

The most important factor in planning for storageon Philippine streams is availability of suitable damand reservoir sites. Existing maps prepared by theUnited States Army have been used by the variousagencies in the initial study of some projects. Generallythese maps have been found to be not accurate enoughfor purposes of determining reservoir capacities—actualcapacities obtained from instrument surveys beingonly one-third to one-half of those revealed by themilitary maps. There are cases where a project mayappear feasible from these maps and yet prove to beunfeasible when instrument surveys are undertaken.While the value of these maps for preliminary workcannot be totally discounted, there is need for betterand more reliable maps of at least the principal riverbasins.

One limitation to storage development in manypotential sites in the Philippines is the displacementof inhabitants of valleys that may be submerged byreservoirs. The development of excellent reservoir sitescan similarly not be undertaken on account of socio-economic problems that may arise with the possibledisplacement of inhabitants within the reservoir area.Experience has shown that these problems cannot beignored in planning for storage development.

The financing aspect of storage projects, either on asingle purpose or multi-purpose basis, presents anotherbig problem to a country with limited financial resourcessuch as the Philippines. This type of project normallyinvolves huge capital expenditures, and unless benefitsconsiderably outweigh the costs, limited financingmeans would discount the possibility of pushing throughsuch projects. Consequently, storage development forconservation uses will have to be confined to a fewselected rivers of great potential value to the regionand to the country as a whole.

It is noteworthy, however, that despite knowndeficiencies of data the National Power Corporation,with the aid of short-duration check observationsrepeated in some cases annually for two or more years,field surveys conducted to supplement available topo-graphic information, and localized but intensive geologic

First type: Two pronounced seasons; dry fromNovember to Aprii; wet during the rest of the year.

Second type: No dry season with a very pronouncedmaximum rainfall from November to January.

Third type: Season not very pronounced; relatively dryfrom November to April and wet during the rest of theyear.

Fourth type: Rainfall more or Jess evenly distributedthroughout the year.

\Z\m \ZV 123* 124* IZ5*

FIG. 9. Climate map of the Philippines.iff»

investigations, and through careful and skilful co-ordination and analysis, succeeded in building up amass of information sufficient to serve as a reasonablebasis for planning the complete development of suchmajor river systems as the Agno, Angat, Agos, andMarikina on Luzon and the Lake Lanao-Agus RiverSystem on Mindanao.

As a result of these studies, the Ambuklao Projecton the Agno, the first of a series of six projects intendedto harness the complete potential of the river forpower and irrigation, has been undertaken and is nownearing completion at a cost of about U.S. $65 million,of which $20 million was borrowed from the UnitedStates Export-Import Bank while the 25,000-hectareAgno Irrigation System is now under construction.Two units of the Maria Cristina Falls Project, whichis one of the six power projects intended to developthe total potential of the Lake Lanao-Agus RiverSystem have been undertaken. The first unit wascompleted in early 1953 and has since been supplyingthe power requirements of the Maria Cristina FertilizerPlant, the steel mill of the National Shipyards andSteel Corporation, and a private chemical manufactur-ing plant in the Iligan area. The second unit is aboutto be completed.

The Marikina River Project is intended to be acombined power, water supply, flood control and irriga-tion scheme, to serve Manila and its environs. Thereis a possibility that its construction will be under-taken soon.

It may also be mentioned in this connexion that theBureau of Public Works, in the face of similar defi-ciencies of data, has constructed a total of 31 majorirrigation systems of the purely diversion type coveringa total area of nearly 141,000 hectares of riceland. Ofthese, 18 or nearly 60 per cent are reported to be operat-ing efficiently. The main hydrographie activity inconnexion with these projects—so as to supplementinadequate rainfall and other data—was the establish-ment of gauging stations where flow rates were deter-mined and recorded for continuous periods of at leastfive years at each station.

These activities, although intended for individualprojects and not for the general purpose of adding tothe existing store of basic hydrologie information, haveadvanced Philippine knowledge of the country's waterresources.

Watershed Management

The indiscriminate denuding of the forest cover in thewatersheds is considered to be the principal factorcontributing to the gradual diminution of flows of thestreams during the dry season and to the increasingdestructiveness of floods. This, in addition, not onlycontributes to soil erosion, but also reduces the reten-tion capacity of the soils necessary for plant growth.The need to pursue vigorous, extensive and well co-ordinated programmes of watershed management, with

the attainment of the proper balance of forest coverin the watersheds as the ultimate goal of such pro-grammes, is imperative.

PROBLEMS RELATED TO IRRIGATION

The great need for attaining self-sufficiency in riceand other staple foods for the needs of the growingpopulation makes irrigation a primary considerationin water resource development in the Philippines.Problems related thereto, in addition to those pre-viously discussed under water resources developmentproblems in general, are the following:

Inadequate data on irrigation water requirements. Ofequal importance with basic hydrologie data in thedesign of irrigation systems is adequate knowledge ofwater requirements. A consideration of both thesefactors is necessary in the determination of the irrigablearea. The present practice of providing a continuousirrigation diversion of 1.5 second-litres per hectare forrice crop requirements and for normal canal and relatedlosses, irrespective of soil types and crop varieties,results in either wastage, over-use, or shortage of water.Water requirements need to be predicted with reason-able accuracy if agricultural production is to derivemaximum benefits from irrigation.

To the writer's knowledge, very little study or researchon this important subject has been undertaken.

Lack of basic production costs and economic data. Whereinvestments are large, as in the case of storage projects,greater accuracy in economic studies is a necessity.Benefits from irrigation are normally figured by compar-ing yields and production costs before and after irriga-tion, and the results and conclusions arrived at canonly be as reliable as the data on which they are based.The need for better and more accurate data is greaterwhere alternative developments are being compared,as these could greatly influence the choice of develop-ment. To date, very little information about productioncosts for rice and other principal crops that couldbenefit from irrigation is available, and such informa-tion as is available needs to be brought up to dateand corroborated.

Inefficient irrigation practices. Deficiencies of irrigationsystems in the Philippines can, in part, be traced toinefficient methods. In most farms, the importanceof a profitable cropping programme is not well under-stood. Growing rice to the exclusion of other cashcrops is a practice that, more than any other factor,has contributed to the slow progress of agriculture.It is most important that the various agencies of thegovernment should join efforts in mapping out croppingprogrammes for the various communities and regions,so that farmers will get rid of the centuries-oid customof growing only rice and will plant other profitable

crops which do not require as much water as riceduring the growing season.

Another practice which must be corrected is the mereflooding of the fields regardless of whether it wouldbe beneficial or detrimental to the growth of crops.Much valuable irrigation water is wasted through thispractice.

Deficiencies of irrigation systems. In the design of manyirrigation systems in the Philippines, there has beena tendency to overlook drainage facilities, which areas important as provisions for bringing water to thefields. It has been observed, particularly in privatesystems, that there is generally a lack of control andregulatory structures which results in damage to irriga-tion canals or to farms themselves, and in avoidablewaste o£ water. There is need for looking into thisproblem and improving the existing systems.

PROBLEMS RELATED TO WATER POWER

DEVELOPMENT

The scarcity of readily usable fuel resources, and thehigh cost and socio-economic undesirability of toogreat dependence on imported fuels, makes it onlynatural that the Philippines should turn to its waterresources for the supply of much-needed power fordomestic and industrial uses. During the last few years,there has been an intensification of activities in waterpower development, primarily as an effort to acceleratethe industrialization of the country. Problems relatedto power development aie discussed hereunder.

The need for an assessment of potential resources. ThePhilippines are endowed with an abundance of rainfalland a topography generally favourable for hydro-power development; the country has immense waterpower resources. Despite the efforts of the NationalPower Corporation in the direction of assessing thecountry's total water power potential, not much,however, has really been accomplished to date. Lackof accurate and reliable maps and lack of dischargedata for many apparently promising streams are thedrawbacks to a scientific and systematized evaluationof the water power resources. There has been a conti-nuous investigation and survey throughout the country,but both equipment and funds necessary to carry thetask to completion are insufficient. To be of real helpin long-range planning and in the scheduling of prioritiesand fund requirements, this appraisal must cover atleast all the major river basins in the various regionsand islands.

Fig. 10 (see end of book) is a map of the Philippinesshowing the progress of hydro-electric development inthe country, and the various streams already investiga-ted and studied. There are many more streams of greatpotential value that have not been evaluated and are notincluded in the chart.

Lack of geological data and project sites. The develop-ment of many streams in the country, particularlythe chief rivers, as previously pointed out requires theconstruction of storage dams. The geological problemsattendant on the construction of high dams are enor-mous. Investigations are carried out at great expense,as experienced in the various projects of the NationalPower Corporation. Geologic investigations have tobe undertaken from scratch in view of the absence offundamental engineering geologic data on even themost important development sites. There is a needfor carrying out a geologic exploration programme inthe major watersheds of the country, but neitherequipment nor trained personnel are readily available.This programme should extend to a survey of possibleconstruction materials for the dam.

Lack of specific hydrologie data. Of the specific hydrologiedata needed in the evaluation and planning of hydro-electric projects, the most important are those of day-to-day stream flow, evaporation and other water losses,flood hydrographs, and sediment transport. These dataare either inadequate or non-existent for many streamsof importance. In many cases gauging records arediscontinuous or, when available, are not for indicateddiversion sites. It is not infrequent, therefore, thatwater supply studies have to be carried out on theassumption of a straight-line variation of stream flowwith drainage area, with all the attendant risks ofinefficient operation if predictions do not turn out tobe as expected. In the design of hydraulic structures,lack of accurate flood intensity-duration data hasresulted in either over-design in the case of major pro-jects or under-design in the case of minor diversionstructures, both being undesirable from the economicstandpoint. Also on account of lack of data on evapora-tion and other reservoir losses, these factors have notbeen adequately considered in project water studies.While no appreciable damage has resulted from theneglect of these losses in design, their effect cannotbe discounted, particularly in important projects. Dataon quantities of sediment carried by streams, whichare very important in estimating the life of reservoirs,are unavailable.

WATER SUPPLY PROBLEMS

Aside from the common problem of financing that haseffectively restricted water resources development ingeneral, and in addition to the deficiencies of surfacewater hydrologie data discussed above, the main prob-lems that have to be solved in the field of watersupply are the lack of adequate, reliable data on theextent and nature of present and future uses; thealmost total lack of hydrologie and other data withrespect to ground water; lack of modern equipmentand personnel trained in the latest methods of wellconstruction, testing, and rehabilitation and yield

Problems of humid tropical regions/Pro blêmes des régions tropicale^ humides

measurement ; and shortage of personnel with sufficienttraining and experience in the geology and hydraulicsof ground water formations.

The problem of forecasting demand. The problem ofpredicting the extent and nature of future uses of water,whether from surface or from sub-surface sources,depends in turn on the problems of population forecast-ing in the case of domestic uses and of industrialdevelopment projection in the case of industrial uses.The last census was taken in 1948 when as an after-math of the second world war, conditions were notentirely normal. It is not known when the next censuswill be taken and, although vital statistics and immigra-tion and emigration records are available on a year-to-year basis, the lack of sampling surveys during theintercensal interim makes population projection verydifficult, especially in the case of small urban areaswhere the presence of a relatively large number ofprivate individual water supplies operated withoutrecords makes an accurate estimate of water supplyneeds very nearly impossible. The problem is furthercomplicated in the case of small areas by the unrecor-ded and much easier movements of population out andinto each particular area than in and out of the country.

In the matter of industrial areas, reliable estimatesof the magnitude and nature of future uses of water,except in the case of sugar mills, is even more difficultbecause of the almost total absence of information.

Deficiencies in techniques of construction and testing.Scientific methods of testing, measuring, and forecast-ing well capacities and aquifer yields are almost totallyunknown. While there are over 13,000 wells drilledand logged by the Bureau of Public Works to date,no serious effort has been made to utilize standardterminology in the logging, much less to analyse thelogs so as to establish the characteristics of aquiferspenetrated with a view to assuring or estimating thesuccess of future wells. Standard well-screens are notutilized and the gravel wall well has not been intro-duced. In cases of wells drawing from unconsolidatedmaterials, the well casing itself is perforated and madeto serve as a screen without either the size or locationof perforations being correlated with the materials inthe aquifer. It is not surprising that the percentageof well failures is rather high, some of these failureshaving occurred within five years of the terminationof construction. At the same time, the lack of equip-ment and personnel versed in modern methods of wellrehabilitation has caused the total abandonment ofwells that have failed, without any attempt to recovertheir original capacities.

Deficiencies of geological information. Lack of suffi-ciently detailed geological information about groundwater formations has made it difficult to plan orderlydevelopment of ground water sources, despite the

obvious need for them to supplement surface servicesso as to meet both domestic and industrial requirementsand also that of irrigation. In general, most wells sofar constructed draw either from sand and gravelformations or from sandstones, but most of the pro-perties of these materials are not determined withsufficient accuracy to enable the construction of wellsto be designed for maximum efficiency and life.

Partly because of these problems and also becauseof the major problems of increasing depletion of theforest cover and the natural increase in demand, thereis a consistent lowering of the water table in manyareas where substantial ground water utilization isin progress.

PROBLEMS OF FISHERIES DEVELOPMENT

Fisheries development, while constituting a phase ofwater resources development, presents special problems.

These relate largely to financing and technologicaldeficiencies. Marine fisheries development is restrictedby the lack of modern equipment, such as refrigeratedvessels, commercial type gear, and efficient canningfacilities. Information relative to marine life itself,its major forms, location and nature of the best fishinggrounds, and marine phenomena are sufficiently avail-able to enable profitable, large-scale exploitation ofthe marine resources to be undertaken once the neces-sary equipment becomes available.

Fresh water fisheries are generally operated withcenturies-old equipment and techniques. Problemsrelevant to this type of activity, in addition to thefinancial and the technological, are the need to accumu-late additional information on the food and dissolvedoxygen requirements of commercial species, on theability of prospective fishery waters to meet theserequirements, and the need for more definite evaluationof the possibilities of stocking areas of deficiency withnon-indigenous species.

A corollary problem is the need for research on thepotentials for development of processing industriesbased on fish and other marine resources as part of theindustrial development planned.

SOIL CONSERVATION PROBLEMS

First the very pronounced soil wastage brought aboutby the country's high relief, high rainfall intensity,and the progressive reduction of forest cover due tolack of enlightened logging practices; then the preva-lence of wasteful, antiquated farming practices; andlastly, the lack of facilities for effective developmentof a system of soil conservation farming.

Part of the great natural wealth of the Philippinesconsists of its luxuriant forest cover. Its commercialforests cover about 38 per cent of the land area andhave been variously valued at from $24 to $30 million,with an annual yield potential estimated at from

$500 to $1,000 million depending on the degree ofprocessing applied.

Since there is a ready market for logs and otherforest products in Japan, the United States and else-where, logging activities have been expanding at arate that poses a growing danger of ultimate defores-tation in view of the general lack of systematic reforesta-tion. There are only two timber concessions, in theSouth Philippines, where the sustained yield systemof development is followed.

In addition to unwise commercial logging practices,there is the problem posed by the system of farmingpursued in certain areas, largely by primitive tribes,consisting of burning out portions of the forest coverfor planting subsistence crops for a few seasonsbefore they move on to other areas where the cycle isrepeated.

The greatest erosion control problem now facing thePhilippines is the threat caused by these unwise prac-tices to the maintenance of the forest cover. Alreadymany areas in Northern Luzon around Baguio, onCebu Island and elsewhere, have been so denuded thatextensive sheet and gully erosion has developed, accom-panied by a natural reduction of ground water storage.An instance in point is the watershed of the AmbuklaoHydro-Electric Project reservoir, just north of Baguio,where erosion is extensive enough to reduce the esti-mated useful life of the reservoir to 60 years. Practicallyall the main river systems of Central Luzon providingirrigation water are so silt-laden that they pose aproblem during the rainy season as well as in theyear-to-year operation of diversion structures andcanals.

The Bureau of Forestry bears the responsibility forconserving the forest resources and exercising generalregulatory control over forestry operations, but it hasnot been able to undertake reforestation of denudedareas at an adequate rate. One of the problems theBureau has been forced to face and which has made itnecessary to divert part of the funds available forreforestation is the need to guard against illegal harvest-ing and utilization of standing timber.

Soil conservation problems other than those ofcontrol of erosion in forested areas are, on the otherhand, the responsibility of the Bureau of Soil Conser-vation, established only within the past five years.

The main problem of the Bureau of Soil Conservationis the erosion of farmed slopes. It is also undertakingextensive soil surveys in order to meet another pressingproblem—the need for adequate knowledge of soil typesand characteristics so that it can guide the better utili-zation of the land on the basis of its capability, theadoption of soil erosion control measures in farming,and the employment of better soil management prac-tices according to the properties of the soil. This neces-sarily involves the problem of securing the adoptionof such measures as contour farming and furrowing,contour subsoiling, terracing, cover cropping, drainage,

fertilizer use, crop rotation, irrigation, gully control,pond management, etc.

PROBLEMS RELATING TO FLOOD CONTROL

Flood damage in the Philippines has consistentlyincreased during recent years, primarily on accountof unscientific watershed management practices, result-ing in the gradual stripping of the forest cover of majordrainage basins, and the progressive development ofareas likely to be affected by high water. Much concernhas been expressed after every flood, particularly inManila, where floods are practically an annual occur-rence and where damage reaches staggering propor-tions. Problems which make the control of floods inthe various regions of the country difficult are:1. Lack of storm frequency or flood magnitude-fre-

quency data, even in the most important areassubject to inundation.

2. Inadequate data on flood damage, there being nosystematic survey of damage on either public orprivate property immediately after floods occur.

3. Insufficiency of funds.The first two are related to the planning and designof flood control facilities, as well as to their economicevaluation. Without these data there is necessarily agreater tendency to be conservative and therefore, uneco-nomical, in providing the necessary remedial measures.

It is to be deplored that there are very few recordinggauges in the country for the measurement of eitherstream flow or rainfall. In some instances there seemsto have been difficulty on the part of technicians toappreciate sufficiently the value of recording equip-ment. Flood damage surveys are not a standard prac-tice. An instance in point is that in the planning of theMarikii a River Multi-Purpose Project, one aspect ofwhich is the control of floods in Manila, a flood damagesurvey was only conducted long after the floods occurredand on y when these data were badly needed in theeconomic evaluation of the project.

PROBLEMS OF STREAM POLLUTION AND DOMES-

TIC AND INDUSTRIAL WASTE TREATMENT

The principal problems here are legal and sanitary innature, in addition to the usual financial problem andthe problem of insufficient information.

Pollution of Philippine streams originates from thedischarge of either domestic or industrial wastes. Fortu-nately, from a national point of view, it is still relativelyinsignificant in comparison with that of streams inEngland and parts of the United States of Americain the past, which led to the enactment of the presentregulations in these countries.

Pollution from domestic sewage is a problem inManila and its environs, and in a few other cities andtowns. In Manila, pollution from sewage affects thefish ponds and shellfish beds in Malabon to the north

and the bathing beaches at Baclaran and points south.The Pasig River and its tidal branches are heavilypolluted with surface drainage and garbage. The prob-lem, in Manila as well as elsewhere, is that there areno legal standards of maximum allowable pollution andno data on the capacities of receiving streams toabsorb pollutional loads without creating nuisances oradversely affecting fish life.

Another problem in Manila and most other Philippinecities and towns is the fact that most households arenot served by the sewerage system and depend onindividual septic tanks and other similar or even lesssatisfactory methods of treatment and disposal, whichcan result in contamination of ground water supplies.

With reference to industrial waste disposal intostreams or bodies of water, it is again fortunate thatthe low rate of industrial development to date has notmade the problem of proper disposal very urgentthroughout the country. The problem at present islocalized in mining areas and at the sites of a few largeindividual manufacturing establishments. As in thecase of domestic waste disposal, the chief problem isthe lack of legal standards prescribing allowable levelsof pollution. One law in force which helps to a certainextent is the one that prohibits the dumping intopublic streams of any material that may change theircourse or carrying capacity.

SUMMARY OF PROBLEMS

Viewed from an overall perspective, the most importantproblems connected with the development of the waterresources of the Philippines, arranged roughly in theorder of their relative importance, are:1. Lack of funds, equipment, and skilled personnel in

certain areas of activity.2. Lack of hydrologie, geologic, economic and other

data and of the equipment and skilled personnelneeded for their accumulation, evaluation, andpresentation in readily usable form.

3. Substantial uncontrolled soil erosion and depletionof the forest cover.

4. Antiquated techniques and equipment in mostareas.

5. The need for co-ordinating data—gathering acti-vities and research, and for disseminating informa-tion among possible users.

R E V I E W OF RESEARCH AND SURVEYACTIVITY

RESEARCH COMPLETED OR UNDER WAY

The bibliography at the end of this paper, although byno means complete, indicates the sad dearth of researchin water resources development, especially in the more

basic areas of evaporation, evapo-transpiration, anddeep percolation, run off, ground water hydrology andhydraulics, stream flow, and rainfall intensities andduration.

There is only one research study on evaporation sofar undertaken and completed, by Quisumbing [3].1

This study attempted to establish certain coefficientsbetween rates of evaporation from open pan, shadedrim pan, etc., as related to the probable rate of evapora-tion from the free surface of large bodies of water ; butthe limited coverage of the study precludes generalacceptance of its results. While the Weather Bureau,the National Power Corporation and the Bureau ofPublic Works maintain a few stations for accumulationof evaporation data, these were not established pri-marily for research and hence there has so far been noattempt at correlation and detailed analysis of theirobservations.

Wendover [4] has attempted to establish the relation-ship of transpiration from the forest cover to streamflow, but the study again suffers from limited coverage.

There has been much more activity in meteorologyand climatology, especially in rainfall, where recordsin the Manila area date back at least to the later partof the nineteenth century. The most important defi-ciency in rainfall research is in the intensity and dura-tion of storm precipitation, owing to the lack of record-ing gauges. Philippine cyclonic storms (typhoons)have also received some attention, Depperman [7, 8]being one of the leading students of these phenomena.The Weather Bureau, in co-operation with the UnitedStates Navy, is actively pursuing further research inthis direction.

As regards run-off, deep percolation, and sub-surfaceflow there is total lack of research activity.

In geology and in most of the specialized fields likepower, flood control, etc., studies and reports availableare more the results of operational or project develop-ment surveys than of deliberate research. The biblio-graphy at the end of this paper includes most of themore significant papers on these subjects.

In power development, one specific research studyundertaken prior to construction was a hydraulicmodel investigation of the spillway of the AmbuklaoProject.

In irrigation, some research has been undertaken inthe water requirements of rice and sugar [15, 16] butthere is urgent need for much more extensive workconcerning the requirements of Philippine agriculturalcrops in general.

In fisheries and soil conservation, a substantialamount of research has been undertaken but only aminor part of this has direct significance for waterresources development per se.

Mention has been made elsewhere in this report ofthe contribution to hydrologie and geologic information

1. Figures in brackets refer to the bibliography on page 98.

made by the extensive studies undertaken by theNational Power Corporation in planning for the com-plete development of the Agno, Angat, Marikina, andLake Lanao-Agus river systems and by the Bureauof Public Works in the design of 31 major irrigationsystems.

Relevant research activity at present in progressincludes:1. Meteorology. Research being conducted by the

Weather Bureau on the development and behaviourof Philippine cyclonic storms or typhoons, theirdetection, the prediction of wind force, and theforecasting of changes in direction or speed of thecentre or eye.

2. Irrigation. The effect of the rate of application ofirrigation on the growth and yield of certain speciesof corn and other crops, by Aglibut et al oí theUniversity of the Philippines College of Agriculture.Also by the same investigators, research under wayon rice plant-water relations and the fluctuations ofthe temporary water table in connexion with theuse of underdrains. The Bureau of Plant Industryis engaged in research on the effect of differentdepths of submergence on rice growth, while theCollege of Agriculture, University of the Philippines,is conducting various studies on the consumptiveuses of water in agriculture.

3. Flood control. Studies in progress are Delena'sresearch concerning the relation between typhoonsand flood-producing rainfall (Bureau of PublicWorks) and Gordon's on the irrigation oí sugar-cane.

4. Soil conservation. A number of investigations areunder way on the effect of different types of vege-tative cover on erosion control, the available watercontent of different soil types, improved water andsoil management practices, and effectiveness ofvegetative and mechanical erosion control methods.

SURVEYS UNDER WAY

Much of the continuing activity in the accumulationof data necessary in water resources developmentconsists of routine operational activities of specificagencies:Weather Bureau—climatological, meteorological, geo-

physical and astronomical observations.Bureau of Public Works and National Power Corpora-

tion—stream flow and some rainfall and evaporationobservations in co-operation with the WeatherBureau; also topographic and geologic investigationsat project sites.

Bureau of Public Highways—topographic surveysalong proposed highway routes.

Bureau of Mines—general geologic and mineralogieinvestigations.

Bureau of Soil Conservation—soil classification.A project of great significance for the future of water

resource development in the Philippines is the newlyinitiated undertaking described below.

A Co-operative Project on the Gathering of Basic Data

The vital need for basic hydrologie and other data toplace the planning and development of water resourcesin the country on a sound basis, and for the orderlysolution of related problems is readily apparent. Awareof this need, the various government agencies concernedwith the different phases of water resources develop-ment initiated a programme jointly with the UnitedStates Government, through the International Co-operation Administration, for undertaking a vigorousprogramme of procurement and compilation of neces-sary data. The organization and mechanics for the im-plementation of this project have already been workedout and actual implementation was started in 1955.

The objectives of the project, as set forth in theproject proposal, are:Establishment of priorities among major projects

primarily multipurpose in character and includingirrigation, power development, water supply, andflood control considerations.

Definition of problems and discovery of methods ofsolution of problems related to projects under consi-deration.

Establishment of a continuing programme of collectionof accurate hydrologie data and economic statisticsnecessary for the sound planning and constructionof water resources development facilities.

Establishment of the organization and technical pro-cedures necessary for multi-purpose programme andproject planning.

With these goals established, the initial work programmeproposed is as follows:Study and analyse existing information, and recon-

noitre specific areas, so as to determine the potentialfor consolidation and expansion of single-purposeprojects for multi-purpose use. This phase wouldinclude dam and reservoir location, examination anddetermination oí priority phases of development,general economic and engineering feasibility, possiblecosts and benefits involved, additional informationrequired to establish feasibility, and methods ofapproach to unsolved problems.

Rehabilitate and provide minimum equipment foroperation of 127 gauging stations now being operatedin an extremely inadequate manner.

Examine and make recommendations as to adequacyof and need of some 200 additional gauging stationspresently proposed for establishment.

Establish a minimum programme oí rainfall, sedimentand evaporation data collection; determine theiradequacy for existing and future needs; and recom-mend reduction or expansion of the programme onthe basis of project development needs.

Establish within the Central Plain of Luzon, prelimi-

nary to later expansion to other areas, a programmeof pilot well development based on data to be col-lected through exploratory drilling and test pump-ing, supplemented by compilation and analysis ofscattered inadequate existing well information.

Establish the organization, technical procedures andstaff to continue investigation and analysis of waterresources, both surface and sub-surface.

Responsibility for direction of the work involved restswith a Water Resources Development Committeewhose membership consists of a responsible staff memberfrom each of the government entities concerned withwater resources development, direct responsibility forprogramme execution being placed on the IrrigationDivision of the Bureau of Public Works. Financialrequirements during the first year of programmeexecution, amounting to $245,000 and 240,000 pesos,were met jointly by the United States and PhilippineGovernments, the former with respect to the dollarrequirements for equipment and technical assistanceand the latter for the local expenditure require-ments.

This project is the first determined step towardsunifying, and alleviating present deficiencies in, basicdata necessary for the formulation of a practicable planof water resources development, both short and longrange. It will contribute to the economic and engineer-ing soundness of future works.

RECOMMENDED DIRECTIONS OF WORK,INVESTIGATIONS, SURVEYS, ANDA P P L I E D RESEARCH

The problems discussed above illustrate the difficultiesthat are being encountered by those engaged in thedevelopment of water resources in the Philippines.While efforts are being exerted to remedy the situation,particularly in the procurement of basic data necessaryin placing water resources development activities ona sound foundation, much remains to be accomplished.The directions of future work in the administrative oroperational, research, survey, and investigative areasof water resources development might to advantageconsist of the following:The creation of a central information collecting agency,

to collect, compile and prepare and publish fordissemination all basic data required in projectsinvolving the utilization of water, consisting mainly

of stream flow, rainfall, evaporation, sedimentation,percolation, transpiration, consumptive use, andothers.

The standardization of methods and procedures andthe adoption of more modern equipment in theprocurement of basic hydrologie and other dataapplicable to Philippine conditions, as well as theutilization of approved terminology and units usedin water resources development in order to allowcorrelation and comparison with similar informationfrom other countries.

A careful review of existing data-collecting installationsand facilities, to determine those that do not effec-tively serve their purpose, with a view to abandoning,replacing or relocating them on more favourable sites.

The immediate establishment of stream-gauging sta-tions in all the principal rivers of the country, withautomatic recorders in those subject to destructivefloods, as a minimum requirement, and providingfor continuous observations to be made thereat.

The immediate establishment of recording rain gaugesat the watersheds of principal rivers subject todestructive floods.

The establishment of evaporation stations in criticalareas to gather basic data and the prosecution ofresearch on the subject, as well as on transpiration.

The establishment of sediment-sampling stations incritical rivers, and the study of the data derivedtherefrom.

Intensification of the ground water survey alreadymapped out, and extending the same to cover thecritical drought regions so that these may immediatelybe taken advantage of in alleviating conditions ofscarcity in these areas. Corollary geologic investiga-tions should also be carried out.

New subjects of inquiry might to advantage include.The possible utilization of solar energy in power pro-

duction and in process industries.Research on the long-term possibility of producing

potable water from the sea at economic cost. Thisis particularly important in the densely populatedsmaller islands like Cebu and Bohol and probablyeven in the bigger islands as the threat of large-scale deforestation continues unabated and shouldindustrial development occur at an accelerated pace.

Investigation of the possibilities and economics ofartificial rainmaking as a supplement, at need, tonatural supplies in areas of either temporary orpermanent deficiency.

Appendix

THE CLIMATE OF THE PHILIPPINES

The Philippine Archipelago extends from north to southover 13 degrees of latitude in the tropics. It is divided intomore than 7,000 islands, whose form and area vary exceed-ingly but whose combined area is about 114,400 square miles.Some, as Luzon and Mindanao, cover an extent of over30,000 square miles; 9 have a surface of between 1,000 and6,000 square miles, 20 between 100 and 1,000, 73 between 1 and100 square miles, with more than 6,800 islets of less than1 square mile each. Bearing these facts in mind and consider-ing also the bold relief of some of these islands, constitutingvarious plateaux in the mountainous regions, we can readilysee that they give rise to a decided variety of climatic condi-tions which cannot be comprehended in a single or uniformtype of climate. The foundations for a classification of climatemust necessarily be based on observation and experience.These show that the difference of climatic conditions foundin the different parts of the archipelago depend mainly onthe local air currents, which in turn are a result of thegeneral air streams, the position of the islands, and the mostusual storm tracks.

Purely local air currents are caused by the various thermalconditions of the islands and their adjacent seas, and theyare more or less independent of small differences of latitude ;the general air streams, however, are caused by the thermaldifferences between polar and equatorial regions, or owetheir existence to the normal differences of temperaturecorresponding to latitude. The influence of the general currentsor latitude upon some of the climatic elements for the Philip-pines may be very slight.

Generally speaking, we can divide the main Philippineair currents into three groups: (a) the northers (loosely calledthe north-east monsoon), streaming along the easterly andnorth-easterly side of the great Asiatic high pressure areas ;(b) the trade wind, reaching the islands from a generallyeasterly direction and coming from the tropical high pressurearea of the Pacific; and (c) equatorial air (loosely called thesouth-west monsoon), pushing its way across the equatorfrom the strong tropical high pressure areas of the southernhemisphere. The general direction of winds from these threesources are as follows: (a) from north to east (northers andtrade) from October to January; (b) from east to south-east(trade wind) from February to April; (c) for the rest of theyear southerly directions, mainly south-west (south-westmonsoon and the influence of typhoon centres). Air currentsfrom north-west and west are generally of cyclonic origin.

Since temperature differences in the archipelago are slightand since rainfall differences are on the contrary importantand decidedly variant, owing to the combined influence oftopography and air stream direction, we shall base our classi-fication of Philippine climate upon the types of rainfall. Inother words, the four types of climate chosen will be basedupon the presence or absence of a dry season and of a maxi-mum of rainfall in the winter:

First type. Two pronounced seasons ; one dry in winter andspring, the other wet in summer and autumn. All the regionson the western part of the islands of Luzon, Mindoro, Negros

and Palawan are of this type. The controlling factor is topo-graphy. The localities of this type are shielded from thenorthers and even in good part from the trades by mountainranges, but are open to the south-west monsoon and cyclonicstorms.

Second type. No dry season; with a very pronounced maxi-mum rain period in winter. In this class fall the Catanduanes,Sorsogon, and the eastern part of Albay, the eastern andnorthern part of Camarines Norte and Camarines Sur, agreat portion of the eastern part of Quezon, Samar, the easternpart of Leyte, and a large portion of eastern Mindanao. Theseregions are along or very near the eastern coast and shelteredneither from the northers and trades nor from the south-west monsoon and cyclonic storms.

Third type. No very pronounced maximum rain period;with a short dry season lasting only from one to three months.Regions with this type of climate are the western part ofCagayan (Luzon), Isabela, Nueva Vizcaya, the eastern por-tion of the Mountain Province, southern Quezon, the BondocPeninsula, Masbate, Romblon, north-east Panay, easternNegros, central and southern Cebu, part of northern Min-danao, and most of eastern Palawan. These localities areonly partly sheltered from the northers and trade rains andopen to the south-west monsoon or at least to frequent cyclonicstorms.

Fourth type. No dry season and no very pronounced maxi-mum rain period. The regions affected by this type are theBatanes Province, north-eastern Luzon, western CamarinesNorte and Camarines Sur, Albay eastern Mindoro, Marinduque,western Leyte, northern Cebu, northern Negros, and mostof central, eastern and southern Mindanao.

Mountain climates might reasonably form another type.However, they can be reduced to one of the above types asfar as certain climatological elements are concerned exceptas to temperature which decreases with altitude, and rainfall,which generally increased with height.

TYPHOON s

In conclusion, a few words on the way in which tropicalcyclones affect the different regions of the archipelago.Unfortunately, all the regions of the four types of climateare exposed to typhoons, since these divisions are mainlylongitudinal in character, whereas typhoon frequency israther latitudinal in type. As a matter of fact and as a resultof long years of experience, we may say briefly that the sou-thern part of the archipelago, up to 8 degrees north latitude,is nearly free from typhoons. It makes the agricultural landsof nearly the whole of Mindanao exceedingly valuable. From8 to 11 degrees north or over a zone of 180 miles wide, thereare about 8 per cent of the more serious typhoons whichaffect the archipelago; this leaves nearly undisturbed thegreat sugar lands of Negros and southern Panay. From 11 to13 degrees north, typhoons are frequent and often destructive.North of that zone there is another zone more than 100 milesin width a little less visited by typhoons, and in this area willbe found the city of Manila. Finally, the northern parts ofthe archipelago up to Formosa are most visited by typhoons.

Les problèmes des Philippines tropicaleshumides, notamment en matière de mise en valeur

des ressources hydrauliquespar

VHon. Filemon C. Rodriguez

Résumé

II s'agit d'un rapport sur les problèmes qui se posentaux Philippines, région tropicale humide, notammenten ce qui concerne la mise en valeur des ressourceshydrauliques (envisagée sous ses divers aspects : irri-gation, production d'énergie hydro-électrique, conser-vation des sols, adduction d'eau, lutte contre les inon-dations, etc.) et sur les recherches en cours au sujetde ces différents problèmes.

Les principaux problèmes relatifs à la mise en valeurdes ressources hydrauliques des Philippines sont, parordre d'importance :1. Le manque de capitaux, de matériel et de personnel

qualifié;2. Le manque de données hydrologiques, géologiques

et économiques, etc., ainsi que de matériel et de per-sonnel qualifié pour recueillir ces données, les évalueret les présenter sous une forme facilement utilisable;

3. La forte érosion du sol et le déboisement;4. Le caractère suranné des méthodes et du matériel

utilisés;

5. La nécessité de coordonner les enquêtes et les recher-ches et d'en communiquer les résultats à ceux quipourraient en tirer parti.

Les recherches relatives à la mise en valeur des res-sources en eau ont été négligées, notamment danscertains domaines fondamentaux : evaporation, évapo-transpiration et percolation en profondeur, ruisselle-ment, hydrologie et hydraulique des eaux souterrai-nes, débit des cours d'eau, intensité et durée despluies.

Il est évidemment indispensable, si l'on veut pouvoirorganiser rationnellement la mise en valeur des res-sources en eau du pays et résoudre méthodiquementles problèmes qui s'y rattachent, de réunir des donnéesde base hydrologiques et autres. Conscients de cettenécessité, les divers organismes officiels des Philippinesont entrepris, de concert avec le gouvernement desÉtats-Unis, une action énergique en vue de réunir lesinformations nécessaires et d'en faire la synthèse.

Water Resources Development in General

1. BUENDIA, J. A.; RAMIREZ, C. S. "Water resource utili-zation and management in the Philippines", Proc. 8thPac. Sci. Congr. 1953 (in press).

2. SANTOS, I. C ; NUGUID, C. P. "Prospects of multiplepurpose development of Philippine Rivers", Proc. 8thPac. Sci. Congr. 1953 (in press).

Evaporation and Transpiration

3. QUISUMBING, E. "The evaporation from the free surfaceof large bodies of water", Nat. Res. Coun., Bull. no. 11,Sept. 1936; no. 26, May 1941; no. 28, Oct. 1941.

4. WENDOVER, R. F. "Observations of the effect on stream

flow of transpiration from the forest cover", Philipp.J. For. 1952, vol. 7, nos. 1-4.

Meteorology and Climatology

5. CRUZ, S. R. "Agricultural meteorology; Philippinerainfall", Plant Ind. Digest Oct. 1949, vol. 12, no. 10.

6. DELENA, A. B. "Winds, typhoons and intense rainfallin the Philippines", Bureau of Public Works, Techn.Rep. Manila, 1940.

7. DEPPERMAN, C. E. "General features of Philippine•weather", Philipp. Stud. vol. 2, no. 2.

8. . "Origin and path of typhoons", Elements Jan. 1953.9. LESACA, R. M. "Rainfall expectancy in Manila", Acta

Med. Philipp. 1950, vol. 7, nos. 3-4.

Bibliography ¡Bibliographie

Geology

10. ALCAHAZ, A. P. "The major structural lines of the Phi-lippines", Philipp. Geol. March 1947, vol. 1, no. 22.

11. FELICIANO, J. M.; TEVES, J. S. "The geology of Phi-lippine inland seas", Proc. 7th Pacific Sci. Congr. 1949.

12. IRVING, E. M. "A new geologic map of the Philippines",Proc. 8th Pacific Sci. Congr. 1953 (in press).

Hydro-electric Power Development

13. RODRIGUEZ, F. C. "Water power in the Philippines",Philipp. Engng Ree. 1940, vol. 5.

14. . "Hydraulic studies of the Caliraya power project",Philipp. Engng Ree. 1941, vol. 6.

Irrigation

15. ALFONSO, D. J.; CATAMBAY, A. B. "A study of the netduty of irrigation water for lowland rice in Galamba,Laguna", Philipp. Agrie. Oct.-Dec. 1948, vol. 32, no. 2.

16. GORDON, A. "On the irrigation of sugar-cane", Sug.News 1952, vol. 28.

Water Supply

17. AGUILAR, R. H.; OCAMPO, L. "Artesian well waters inManila and neighbouring municipalities", Philipp. J.Sci. 1931, vol. 45.

18. FAUSTINO, L. A. et al. "Manila water supplies", Philipp.J. Sci. 1931, vol. 45.

19. LESACA, R. M. "Some chemical properties of Manilatap water and their relation to corrosion of the distribu-tion system", Acta Med. Philipp. 1949, vol. 5, no. 4.

20. . "Notes on Philippine public water supplies",Acta Med. Philipp. 1951, vol. 9, no. 2.

Fisheries

21. MANACOP, P. R. "Our principal marine fisheries",Commerce Sept.-Oct. 1952, vol. 49, nos. 2-3.

22. MARTIN, C. "Outstanding research on fish and fisheriesin the Philippines", Bull. Fish. Soc. Philipp. 1952-1953,vol. 3-4.

23. ROXAS, H. A. ; UMALI, A. F. "Fresh water fish farmingin the Philippines", Philipp. J. Sci. 1937, vol. 63.

24. UMALI, A. F. "Commercial fisheries of the Philippines",Philipp. J. Comm. May 1940, vol. 16, no. 5.

Forestry and Soil Conservation

25. AGLIBUT, A. P. et al. "The influence of rainfall andcultural practices on soil erosion and surface run-off",Philipp. Agrie. 1951, vol. 30.

26. ALICANTE, M. "Government policy on soil conserva-tion", J . Soil Sci. Soc. Philipp. 1949, vol. 1.

27. DACAPfAY, P. "Utilization of wastelands and the econo-mics and development of reforestation in the Philip-pines", Philipp. J. For. June 1949, vol. 6, no. 2.

Flood Control and Drainage

28. ALVIH, A. D. "Candaba swamp: its origin and relationto flood control", Philipp. Geol. Sept. 1950, vol. 4.

29. DELENA, A. B. "Control of the Pampanga river", Bureauof Public Works, Techn. Rep. Manila, 1939.

30. IRVING, E. M. ; ABAD, L. F. "Commentary on the proposedflood control drainage system for Manila", Philipp.,Geol. 1949, vol. 3.

31. TAMESIS, F. "Reforestation and flood control", Govt.Employee August 1937.

Pollution Abatement and Waste Treatment

32. JESUS, P. I. DE; ABDON, G. "Chemical analysis of thesewage of Manila", Acta Med. Philipp. Jan.-March 1940,vol. 1.

33. ; ECHAVES, P. "Studies on the treatment of indus-trial coconut waste", Afore. Bull. Hlth Sept. 1946, vol. 22.

34. HIZON, A. O. "Currents at Manila Bay in the vicinityof Manila Harbour", Bureau Coast Geod. Surv. Manila,1948.

Subject index/index des matières.

agriculture, 27, 29, 32, 50.Amazon, 15,16.

region, 11.estuary group, 12.

Ambuklao Project, 90, 96.animal breeding, 27, 28, 30, 33.Antilles, 29.

Belterra Plantation, 20, 22.bird lice, 73.bluebottle larvae, 73.butterflies, 73.

Caribbean region, 25.panoramic view, 33.

cane mealy bug, 65.caterpillar.

blackheaded, 66.hairy, 65.

Central Americaagriculture, 32.animal breeding, 33.diseases, 33.forestry, 32.

Ceylon, 48.evergreen forests, 48.Veddahs, 49.

coconut palm, 66.cockchafer, 67.coffee, 27.

white borer, 68.Colombo Museum, 75.

deciduous forestCeylon, 48.India, 48.

demographic density, 17.double grafting technique, 20.

Escola de Agronomia da Amazónica, 12,13.

"extractivist" mentality, 19.fisheries, 27, 28, 31, 33.

flood plainsAmazon territory, 12.inland, 13.lower Amazon, 13.

floraCeylon, 45.India, 45.

Food and Agriculture Organization, 22,23, 27.

Fordlandia, 17, 20, 22.forests, 27, 30, 32.

green bug, 68.grow-more-food campaign, 43.

Hispaniola, 29, 30.humid forests

distribution, 47.economic products, 50.ethnology, 49.fauna, 51.

India, climatic zones, 45.insect, pests of

coconut palm, 66.paddy, 64.forests, 69.stored products, 71.

Instituto Agronomico do Norte, 11, 12,13,15, 20.

Instituto Mexicano de Recursos Natu-rales Renovables, 27.

inventaire systématiquedes espèces, 57.des ressources naturelles, 57.

jute, 13, 65.

Marikma River Project, 93.medicinal plants, 51.Mexico, 25.

climate classification, 26.forests, 27.irrigation programme, 26.nutrition, 28.

National Power Corporation, 88, 91, 96.Novais Filho Canal, 15.nutrition, 27, 28, 31, 33.

paddy, 64.Pan-American Institute of Geography

and History, 35."paramba" cultivation, 50.Philippines, 86.

main crops, 87.national income, 86.rainfall, 86.storage projects, 88.

Problèmesbiologiques, 60.de la nutrition humaine, 61.de la productivité des sols, 59.

protection de la nature, 59.Puerto Rico, 29, 31.

rain forest types, 43red palm weevil, 66.red spider, 67.rhinoceros beetle, 66.Rockefeller Foundation, 22.

sal borer, 69, 70.shifting agriculture, 11, 49, 50.siltation canals, 16."slugs", 68.soil(s), 11, 26, 27, 29, 32.South America

central regions, 31.northern regions, 31.

sugar-cane, 64.borer, 65.hopper, 65.cultivation, 30, 75.

tea, 67.teak defoliators, 70.tea mites, 67.

mosquito, 67.tortrix, 68.

termites, 65, 68. water, 26, 29, 32. West Indiesticks and mites, 73. water resources development problems forestry, 30.tropical vegetation classification, 43. fisheries, 92. geology, 29.typhoons, 97. flood control, 93. population density, 29.

general, 88. World Health Organization, 71.water gauge readings irrigation, 90.

Manaus, 13. water power, 91. Zoological Survey of India, 75.Santarém, 13.

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