TEN-YEAR RESULTS OF THINNING AND

FERTILIZING OF A POLE- S I ZED

BLACK WALNUT P LANTAT I ON

F. W. VON ALTHEN

GREAT LAKES FOREST RESEARCH CENTRE

SAULT STE. MARIE, ONTARIO

REPORT O-X-245

CANADIAN FORESTRY SERVICE

DEPARTMENT OF THE ENVIRONMENT

MARCH 1976

Copies of this report may be obtained

from

Information Offiae3

Great Lakes Forest Research Centre,

Canadian Forestry Service,

Department of the Environment,

Box 490, Sault Ste. Marie, Ontario.

PSA 5M7

ACKNOWLEDGMENT

The author gratefully acknowledges the cooperation and support

received from the owner of the plantation, Mr. T. G. Harrison. Without

his assistance the study would not have been possible.

Frontispiece. Thirty-seven-year-old black walnut trees in woodlot

plantation.

ABSTRACT

Nine l/5-acre (0.08-ha) permanent sample plots were established

in 1965 in a 27-year-old plantation of black walnut {Juglans nigva L.) and red pine (Pinus resinosa Ait.) growing on former agricultural land

near the town of Harriston in Wellington County, Ontario. A tenth

sample plot was established in a small black walnut plantation of

equal age but growing in an opening of an adjacent sugar maple

{Acer sacchavum Marsh.) woodlot. Three of the afforestation plots

and the woodlot plot were selected as controls with cutting restricted

to the removal of conifers and dead hardwood trees. Three other plots

were thinned in 1965 and 1970 to a basal area of approximately 70% of

that of the control, while the last three plots were thinned to approx

imately 50% of the basal area of the control, One set of plots (control,

lightly thinned and heavily thinned), was fertilized with 450 lb/acre

(504 kg/ha) of ammonium nitrate, 218 lb/acre (244 kg/ha) of triple

superphosphate, and 200 lb/acre (224 kg/ha) of potassium sulphate in

the spring of 1967. Between 1965 and 1970, nearly all conifers died

of what is believed to have been juglone poisoning. Thinning had little

effect on growth, probably because conifer mortality provided most of

the growing space required by the residual trees. Fertilization

increased diameter and height growth of the 100 largest trees per acre

(0.40 ha) by 27% and 22%, respectively. Average diameter and height

of the walnut trees growing in the woodlot plantation have been nearly

double that of trees in Che field plantation. The next measurement is

scheduled for 1980.

RESUME

En 1965, l'auteur crea neuf places-echantillons permanentes

contenant 1/5 acre (0.08 ha) dans une plantation de Noyerg noirs

(Juglans nigra L.) et de Pins rouges (Pinus resinosa Ait.) ages de 27

ans, sisc en terrain agricole naguere cultive, pres de la ville de

Harriston, Wellington County, Ontario. II crea une dixieme place-

echantillon dans une petite plantation de Noyer noir du meme age mais

sise dans une ancienne clairiere d'un boise d'Erable a sucre

(Acer saccJiarw! Marsh.). II choislt comme temoins trois des places-

echantillons du premier type et celle entouree du dit boise, dans

lesquelles la coupe etait limitee a l'enlevement des resineux et des

feuillus morts. II eclaircit trois autres places-echantillons en 1965

et 1970 pour obtenir une surface terriere d'environ 70% de celle des

temoins, tandis que les trois dernieres places-echantillons furent

eclaircies pour obtenir environ 50% de la surface terriere des temoins.

II fertilise un groupe de places-echantillons (incluant un temoin, une

place legerement eclaircie et une autre fortement eclaircie) avec 450

lb/acre (504 kg/ha) de nitrate d'ammonium, 218 lb/acre (244 kg/ha) de

triple super phosphate et 200 lb/acre (224 kg/ha) de sulphate de

potassium au printemps de 1967. De 1965 a 1970, presque tous les

resineux moururent (probablement) par empoisonnement avec du juglone.

Les eclaircies n'influerent pas sur la croissance, probablement parce

que la mortalite des resineux apporta assez d'espace pour que les

arbres residuels puissent bien pousser. Quant a la fertilisation, elle

augmenta le diametre et la croissance en hauteur des 100 plus gros

arbres a l'acre (0.40 ha) de 27% et 22%, respectivement. Le diametre

et la hauteur moyennes des Noyers dans la plantation du boise devinrent

presque deux fols plus grands que ceux des Noyers dans la plantation en

terrain agricole abandonne. Les prochains tnesurages auront lieu en 1980,

TABLE OF CONTENTS

Page

INTRODUCTION 1

LOCATION AND HISTORY 1

SITE AND STAND CONDITIONS IN 1965 2

Soil 2

Forest floor 2

Tree survival 3

Stem quality 3

TREATMENTS 5

Establishment and first out, 1965 5

Fertilisation 7

Remeasurement and second cut, 1970 8

Remeasurement in 19?'5 8

RESULTS AND DISCUSSION 8

Changes in ground vegetation 8

Number of trees 8

Basal area 9

Diameter and height growth 9

Fertilization 15

SUMMARY 16

LITERATURE CITED 17

APPENDICES

1. Description ot Soil Profiles

2. Results of Soil Analysis by Soil Pits and Horizons

3. Number of trees per acre (0.40 ha) by species before and

after 1965 and 1970 thinnings and 1975 measurements

4. Basal area per acre (0.40 ha) by species before and

after 1965 and 1970 thinnings and 1975 measurements

INTRODUCTION

The value of black walnut (Juglans nigva L.) trees is closely

related to stem diameter and form. Trees 10 in. (25.4 cm) DBH or less

are almost unmerchantable, but those of good form and 20 in. (50.8 cm)

DBH or larger are sold at very high prices. Knowing how to produce

large, well-formed trees in the shortest possible time is therefore

of great interest to owners of walnut plantations and woodlots. The

two most promising approaches to increasing diameter and height growth

are crown release and fertilization. Clark (1967) found that pole-

sized black walnut responded to complete crown release by nearly

doubling its diameter growth within A years. Phares and Williams (1971)

reported that pole-sized walnut responded quickly to crown release and

that the increased diameter growth was uniformly maintained during the

entire 10-year study period.

Phares (1973) also reported that pole-sized and larger walnut

trees, growing on sites of medium fertility, were most responsive to

fertilization, whereas trees growing on fertile bottomland soils gen

erally showed little or no response. Although nitrogen deficiencies

have been encountered most frequently, potassium and other elements

may also be deficient on more sites than is commonly thought (Shear

1971).

To investigate the effects of different intensities of thin

ning and fertilization on survival, growth and form development of

black walnut, a series of permanent sample plots was established in

the late summer of 1965 in a 27-year-old plantation of black walnut

and red pine (Finns resinosa Ait.) growing on former agricultural land.

The 10-year results of this study are reported here.

LOCATION AND HISTORY

The privately owned plantation, located approximately 3 miles

(4.8 km) southwest of the town of Harriston in Wellington County, Minto

Township, Concession 6, Lot 30, covers about 20 acres (8 ha) and is

bounded on three sides by fields and pastures and on the fourth side by

a sugar maple (Acer1 sacah

same time, some white pine (Pinus strobus L.) and jack pine (Pinus banksiana

Lamb.) transplants as well as white ash (Fraxinus amevioana L.) seedlings

were planted where failures had occurred in the rows of walnut. In 1950

and 1951 a small number of white spruce (JPicea glauca [Moench] Voss) trans plants were planted as scattered individuals through the main stand.

At the time of afforestation a 1/3-acre (0.12-ha) plantation of

black walnut was established in a recently created opening in the adjacent

sugar maple woodlot. The source of the planting stock and the method of

planting were identical to those of the field plantation but no pine trees

or trees of any other species were interplanted in the woodland plantation.

SITE AND STAND CONDITIONS IN 1965

Soil

Two soil pits were dug in the field plantation and one in the wood-

lot plantation. Soil profiles were described (Appendix 1) and soil samples

from each horizon were analyzed (Appendix 2). The soil is a loam 17 to 32

in. (43 to 81 cm) deep over very compact glacial till. The Ontario Soil

Survey (Hoffman et al. 1963) places the soil in the Harriston Series, which

rates among the best agricultural soils in southern Ontario.

Laboratory analysis indicated that the former agricultural soil had

been impoverished, especially in organic material and nitrogen. Therefore,

it must be assumed that part of the variation in plantation development

between the field and woodlot planting resulted from differences in soil

fertility. Other factors probably contributing to the differences in

growth were the depth of the A and B horizons and differences in exposure

during the early life of the plantation.

Forest floor

Ground vegetation in the afforestation plots consisted of a few

isolated patches of hawkweed (Hieraaiwn spp.) and grass (Agvopyron repens

L.) growing between the rows of walnut, with virtually no vegetation

present under the red pine canopy. Litter under the walnut trees was

limited to a few branches. Dry needles, up to 1 in. (2.5 cm) in depth,

covered the ground under the rows of red pine, and a few branchlets were

scattered over the surface.

In the woodlot, dense sugar maple regeneration covered the ground

completely with a few broad-leaved weeds scattered throughout the plantation.

There was no accumulation of litter.

Tree survival

In the autumn of 1965 black walnut survival was high. There

was very little mortality and most living trees appeared to be healthy.

Seedling loss during the early age of the plantation was difficult to

estimate, owing to several fill-in plantings; but the owner recalled

that less than 25% of the originally planted walnut seedlings died

during the first few years after planting. In 1975 survival was still

high, with mortality occurring only in the intermediate and suppressed

tree classes.

Conversely, survival of the pine component of the plantation

was very low. After apparently high initial survival, mortality of

all three pine species appeared to have increased greatly during the

years immediately preceding our examination in 1965. Mortality of

jack pine was as high as 80% in several plots, and all living trees

showed heavy loss of needles or needle discoloration. Mortality of

white pine and red pine ranged as high as 60% in some plots, and many

living trees also showed signs of deterioration.

The rapid deterioration of the pine is believed to be the

direct result of poisoning by black walnut. The toxic effect of

juglone, a chemical secreted by the roots of black walnut trees, has

been described by Brooks (1951), but the plantation Itself provides

an excellent example of the incompatability of black walnut and red

pine (von Althen 1968).

Through the middle of the plantation runs a strip of eight

rows of red oak (Quercus rubra L.), alternating with four rows of red

pine. This strip was planted at the same time and in the same arrange

ment as the black walnut—red pine section, the only difference being

the substitution of red oak for black walnut. In contrast to the

decadence of all pine trees growing between the black walnut, those

growing between the red oak are healthy, as is demonstrated by the

abundance of long, dark green needles and by superior diameter and

height growth. The different appearance of the pine trees in the two

parts of the plantation is so striking that it can be readily observed

by walking through the stand (Fig. 1 and 2).

Stem quality

The stem quality of the dominant and codominant black walnut

trees was fair. The most serious defect was the persistence of dead

branches, which resulted in the development of large black knots

(Fig. 3). Approximately 15% of the walnut trees showed signs of

canker caused by Neotria galtigena Bres., which is characterized by

Fig. 1. Sparse foliage and yellow needle color are character

istic of red pine growing between black walnut.

Fig. 2. Sparse foliage and dying red pine in walnut planta

tion on the left contrast sharply with healthy red

pine in oak plantation on the right.

its targetlike appearance and results from the destruction of the

phloem tissues in autumn and the growth of host callus material in

spring and early summer (Fig- 4). None of the canker-Infested trees

appeared to be dying, but stem quality was generally seriously

degraded.

As mentioned previously, most of the red pine trees clearly

suffered from what is believed to be juglone poisoning; this did not

influence stem quality directly, but appeared to be associated with

branch mortality and the resulting excessive taper.

TREATMENTS

Establishment and first out, 1965

To study the effect of three intensities of release on survival,

growth, form development, and high—grade timber production of the

residual black walnut trees, nine permanent sample plots of 0.20 acres

(0.08 ha) each, plus adequate surrounds, were laid out In the field

plantation. Boundaries were carefully surveyed, corner pickets were

placed, and the location of all plots was mapped. Within each plot,

all trees were marked at breast height with a band of yellow paint and

their diameter was measured to the nearest 1/100 in. (0.03 cm). The

number of trees and the basal area per acre (0.40 ha) were calculated.

Since the number of trees of each species and the basal area

density varied substantially from plot to plot, no systematic spacing

or percentage basal area reduction appeared to be a suitable basis for

the first cut. The danger of windthrow, snow and ice damage and

possible sun scald as the result of sudden exposure also prohibited

the removal of all pine trees. Instead, the following procedure was

used to even out plot differences during the first cut and to prepare

the stand for fully regulated spacing in 1970. Three plots with repre

sentative basal areas were selected as controls, and cutting was

restricted to the removal of dead trees (Fig. 5). Three other plots

were thinned to a basal area of approximately 62 sq. ft per acre

(14.2 sq.m/ha) or 70% of the basal area of the control. The last three

plots were thinned to a basal area of approximately 43 sq. ft (9.87

sq.m/ha) or 50% of that of the control.

Trees were marked for removal according to the following order

of preference:

1. dead or dying trees of any species

2. red pine trees directly interfering with the growth of

healthy, well-shaped walnut trees

Fig. 3. Large black walnut knot

resulting from poor natural

pruning.

Fig. 4. Canker caused by

Neatria galligena Bres

Fig. 5. Control plot of field

plantation, 1965

Fig. 6. Control plot of woodlot

plantation, 1965. Notice

superior height and

diameter of walnut trees.

3. diseased, suppressed or poorly shaped walnut trees not

expected to produce high-quality timber

A. any tree whose removal would facilitate an improved spacing

within the limits of the basal area density restriction.

In each plot between 38 and 41 walnut trees (190-205 per acre,

or 469-507 per ha) were selected and marked as potential crop trees

according to their size, form and uniform spacing. All trees marked

for removal were cut and bucked by power saw, and the tree trunk and

limbs were removed from the plot by hand. All residual trees were

pruned to a height of 9 ft (2.74 m). large-scale plot maps were drawn

showing the location and diameter of all residual trees within each

plot. The height of 10 trees in each diameter class was measured to

the nearest foot (30.48 cm) with a Haga meter and height—diameter curves

were drawn.

A tenth permanent sample plot was established in the woodlot

plantation to compare walnut growth with that of the field plantation

(Fig. 6). This plot will receive no treatment and will serve only as

a control.

Fertilization

Only after the establishment of all sample plots and the comple

tion of the first cutting operation did the results of the soil analysis

become available; these showed a possible deficiency in the supply of

nitrogen, phosphorus and potassium. To test the effects of fertilization

in thinned and unthinned stands and to compare the effects of release

with and without additional fertilization, plots 4, 5 and 6 (light

release, control and heavy release) plus surrounds were fertilized in

the spring of 1967 by surface application of the following amounts of

fertilizer:

450 lb of ammonium nitrate to give 150 lb of N per acre

(168 kg/ha)

218 lb of triple superphosphate to give 44 lb of P per acre

(49 kg/ha)

200 lb of potassium sulphate to give 83 lb of K per acre

(93 kg/ha).

Foliage samples were collected from three designated trees in

each of the 10 plots in the late summer of 1967, 1968 and 1969 and all

samples were analyzed lor concentrations of N, P and K.

Remeasuvement and second cut, 1970

All plots were remeasured in 1970 and the number of trees and

basal area per acre (0.40 ha) were calculated by species and plots. As 75% to 95% of the coniferous trees were either dead or dying, all conifers were cut in all plots.

In the three control plots of the field plantation all dead hard

wood trees were cut as well. One mature sugar maple tree in the woodlot plot was cut by the owner. In the three lightly thinned plots the plan

was to reduce the basal area of the hardwood trees to approximately 70%

of that of the control. While this was achieved In plots 4 and 8, plot 3 was wrongly marked and was cut to approximately 50% of the basal area of the control.

In the heavily thinned plots all but 185 to 200 well-spaced

trees per acre (457 to 499 per ha) were cut. This reduced the basal area of these plots to approximately 505! of that of the controls.

Remeasurement in 1975

All plots were remeasured in the autumn of 1975 and the number of trees and basal area per acre (0.40 ha) were calculated fay species and plots. No trees were cut in any plots in 1975.

RESULTS AND DISCUSSION

Changes in ground vegetation

During the last 10 years the opening of the crown canopy favored

the establishment of a fairly uniform, medium-dense cover of grasses with a somewhat heavier cover in the fertilized plots. Patches of blackberries

(Rubus spp.), each covering between 20 and 100 sq. ft (1.86 to 9.29 sq. m) , are scattered throughout the stand.

In the woodlot plot most of the sugar maple seedlings that were present in 1965 have died, while a very few have grown to a height of 3 to 4 ft (0.91 to 1.2 m). A few small patches of broad-leaved weeds or grasses are present in small openings of the otherwise dense canopy.

Number of trees

The total number of live and dead trees per acre (0.40 ha) for each plot in 1965, 1970 and 1975 is shown in Appendix 3 by species and treatments. The number of live trees per acre (0.40 ha) after the 1965 and 1970 thinnings is shown in Table 1.

Table 1. Number of trees per acre after 1965 and 1970 thinnings

1965 1970

Replications Replications

Treatment 12 3 Woodlot 12 3 Woodlot

control 1356 800 965 455 765 490 530 395

light thinning 915 715 835 310a 405 365

heavy thinning 705 755 590 - 200 200 190

Overcut by mistake

Basal area

The basal area data of all trees are shown in Appendix 4 by plot,

species, and year of measurement, while the basal area data of only

hardwood trees are shown in Table 2. With the exception of the woodlot

plot, the net Increment in basal area of the hardwood trees was higher

in all plots during the 1965-1970 measurement period than between 1970

and 1975. The better growth rate between 1965 and 1970 most likely

resulted from the high conifer mortality during that period, which

provided much more growing space for the hardwood trees. Conifer mortal

ity reduced the basal area of residual trees by an additional 21% (plot

4) to 53% (plot 6).

While the thinning treatments have not yet produced the

expected differences in basal area increment according to thinning

intensities, major differences in basal area increment are expected

at the 1980 measurement because the effects of the conifer mortality

will have subsided and competition for growing space will have

increased (Fig. 7 and 8).

Diameter1 and height growth

Average diameters and heights of trees with average basal

area are shown in Table 3 and those of the 100 largest trees per aero

(0.40 ha) are shown in Table 4 by plot, treatment and measurement

period. A comparison of diameter and height growth from different

treatments between 1965 and 1975 reveals that thinning had little

effect on the growth of either the trees of average basal area or the

100 largest trees per acre (0.40 ha). In the heavily thinned plots

the diameters and heights of the trees of average basal area appear

Table 2. Basal area of hardwood trees (sq. ft per acre)'

Plot

no. Treatment

Year of

measure

ment

Total

basal

area Mortality Thinned Residual

Residual

as "A of

fully stocked

control

Gross Net Periodic

periodic periodic annual

Increment Increment increment

control

control

control

10 woodlot

1965

1970

1975

1965

1970

1975

1965

1970

1975

1965

1970

1975

49.32

55.70

28.17

52.90

68.33

32.16

51.70

65.22

67.80

84.22

101.54

3.01

3.57

1.53

2.21

1.53

2.33

4,21

5.65

34.36

49.32

55.70

28.17

52.90

68.33

32.16

51.70

b5,22

67.80

84.22

101.54

17.97

9.95

26.26

17.64

14.96

6.38

24-73

15.43

2.99

1.28

4.95

3.09

3 light

thinning

1965

1970

1975

31.80

41.68

31.67

0.99

0.55

7.26

16.49

24.54

25.19

31.67

77,8

49.1

50,2

Table 2. Basal area of hardwood trees (sq- ft per acre) (concluded)

1 sq. ft/acre = 0,230 sq. m/ha

i

Fig. 7. Control plot of field plantation,

1975

Fig, 8> Heavily thinned plot of field

plantation, 1975

Table 3. Diameter and height of hardwood trees of average basal area by plot and year of measurement

Plot

no. Treatment

1965

DBH

(in.)

Height

(ft)b

1970

DBH

(in.)

Hei ight

ft)b

1975

DBH

(in.)

Height

10-yoar growth

DBH

(in.)a Height

(ft)b

1 in. = 2.54 cm

1 ft = 30.48 cm

Fertilized in the spring of 1967,

Table 4. Diameter and height of the 100 largest hardwood trees per acre by plot and year of measurement

1 in. - 2.54 cm

1 ft = 30.48 cm

Fertilized in the spring of 1967

r.

to have Increased during the last 10 years. However, this increase

resulted from the removal of all small trees, which caused a shift

in average diameter rather than a true increase in growth.

Fertilization

The results of the foliar analyses (Table 5) reveal that

fertilization greatly increased the nitrogen concentration in the

leaves, slightly increased the phosphorus concentration and actually

depressed the potassium concentration.

Table 5. Concentration of N, P and K in walnut leaves from fertilized

and unfertilized trees

Fertilized in the spring of 1967 at the following rates: N - 150 lb/acre

(168 kg/ha), P - 44 lb/acre (49 kg/ha), K - 83 lb/acre (93 kg/ha).

Woodlot plot.

Composite sample of three trees per plot.

16

While fertilization had little effect on the diameter and height

growth of the trees of average basal area (Table 3) it increased the

average diameter and height of the 100 largest trees per acre (0.40 ha)

by 27% and 22%, respectively CTable 4). Since most of the trees in the

final stand are expected to come from the 100 largest trees per acre

(0.40 ha) present in 1975, much of the increased growth derived from

fertilization at stand age 28 will therefore be carried to maturity.

SUMMARY

Nine l/5-acre (0.08-ha) permanent sample plots were established

in 1965 in a 27-year-old plantation of black walnut and red pine growing

on former agricultural land. A tenth sample plot was established in a

small black walnut plantation of equal age but growing in an opening of

the adjacent sugar maple woodlot.

Three of the afforestation plots and the woodland plot were se

lected as controls with cutting restricted to the removal of dead trees.

Three other plots were thinned to a basal area of approximately 70% of

that of the control. The last three plots were thinned to a basal area

of approximately 50% of that of the control. The first thinning in 1965

was used mainly to even out plot differences and to prepare the stand

for a fully regulated spacing in 1970. The 1970 thinning accomplished

this objective.

When the soil analysis of the afforestation area indicated

possible deficiencies in the supply of nitrogen, phosphorus and potassium,

one set of plots (control, lightly thinned and heavily thinned) was fer

tilized in the spring of 1967.

Between 1965 and 197G most of the conifers in the plantation died

of what is believed to have been juglone poisoning because conifers

growing in alternata rows with red oak are still healthy.

Analysis of the 1975 growth data shows that thinning had little

effect on diameter and height growth. It is believed that the failure of

the thinnings to increase the growth of residual trees was most likely the

result of poor timing of the treatments which, by chance, coincided with

the rapid deterioriation of the coniferous component of the plantation.

The mortality of the conifers probably provided all the growing space

required by the walnut trees at that time so that the thinnings did little

to improve spacing.

Fertilization was the most successful treatment. It increased

average diameter and height growth of the 100 largest trees per acre (0.40 ha)

by 27% and 22%, respectively.

17

Average: diameter and height of the walnut trees growing In the

woodlot plantation were nearly double Chose in the field plantation.

This superiority is believed to be the combined result of more favor

able environmental conditions and greater soil fertility of the woodlot

site. Comparison of the growth of the walnut trees in the field and

woodlot plantations provides an excellent example of the importance of

site to the development of walnut plantations.

The next measurement is scheduled for the autumn of 1980.

LITERATURE CITED

Brooks, M, G. 1951. Effect of black walnut trees and their products

on other vegetation. West Va. Univ. Agric. Exp. Stn. Bull.

347. 31 p.

Clark, F. B. 1967. Pole-sized black walnut responds quickly to crown

release. _J. For. 65:406-409.

Hoffman, D. W., Matthews, B. C. and R. E. Wicklund. 1963. Soil

survey of Wellington County, Ontario. Soil Surv. Rep. No. 35,

69 p.

Phares, R. E. 1973. Managing immature trees for more high quality

logs and related products. In Black walnut as a crop.

USDA For. Serv., Gen. Tech. Rep. NC-4:49-54.

Phares, R. E. and R. D. Williams. 1971. Crown release promotes

faster diameter growth of pole-sized black walnut. USDA For.

Serv., North Central For. Exp. Stn. Res. Note NC-124. h p.

Shear, C. B. 1971. Importance of potassium in the nutrition of nut

trees. North. Nut Grow. Assoc. Annu. Rep. 61(1970):25-28.

von Althen, F. W. 1968. Incotnpatability of black walnut and red pine.

Can. Dep. For. Rur. Dev», Bi-mon. Res. Notes 24 (2) : 19.

APPENDICES

APPENDIX 1. Description of Soil Profiles*1

1, Soil pit 1, located in field plantation between sample plots 2 and

3.

HORIZON DEPTH DESCRIPTION

L Almost absent, few twigs and

leaves,

Ap 0-8 in. Sandy loam, very dark grey, high

content of organic material,

slightly stoney, numerous roots.

Loam, light greyish brown, slightly

mottled, friable, numerous roots.

Clay loam, dark reddish brown,

numerous roots.

Silt loam, light grey, very faintly

mottled, high lime content, few

roots.

Jkl C 36 in.+ Loam till, light greyish brown, medium subangular blotchy, very

hard, slightly stoney, calcareous,

no roots.

Moisture regime 3

2. Soil pit 2, located in field plantation between sample plots 8 and

9.

HORIZON DEPTH DESCRIPTION

L Almost absent, few twigs and leaves.

Ap 0-7 in, Sandy loam, very dark grey, high

content of organic material, slightly

stoney, numerous roots.

Fine sandy loam, light greyish

brown, friable, numerous roots.

Clay loam, dark reddish brown, loose,

blotchy, numerous roots.

Silt loam, light grey, large diffuse

mottles, high lime content, numerous

roots.

(continued)

APPENDIX 1. Description of Soil Profilesa (concluded)

HORIZON DEPTH DESCRIPTION

_11 36 in.+ Gravelly silty sand, light grey.

Moisture regime 3

3. Soil pit 3, located in woodlot plantation.

HORIZON DEPTH DESCRIPTION

L Almost absent, few twigs and leaves.

Al 0-4 in. Loam, dark greyish brown, slightly stoney, moderate organic content,

numerous roots.

A2 4-26 in. Loam, light yellowish brown, slight

glei, stonefree, numerous roots.

B 26-32 In. Clay loam, dark brown, hard, blotchy,

numerous small roots.

C 32 in.+ Loam till, light yellowish brown, hard,

calcareous, no roots.

Moisture regime 3

Description supplied by J. R. M. Williams, Ontario Ministry of Natural Resources.

1 in. = 2.54 cm.

APPENDIX 2. Results of Soil Analysis by Soil Pits and Horizons

1 in. = 2.54 cm.

APPENDIX 3. Number of trees per acre lO.40 ha) by apecleB before and after 1965 iind 1970 thinnings and 1975 measurements

b.th. =* before thinning

APPENDIX 4, Basal area per acre (0.40 ha) by species before and after 1965 and 1970 thinnings and 1975 measurements

light

thinning

light

tninning

light

thinning

heavy

ttilnning

heavy

thinning

heavy

tninning

control

control

control

control

b.th. 31-80 0.32

cut 7-26 0.32

residual 24.5a 0

b.th. 25.30 0.12

cut O.fc6 0.12

residual 24,84 0

b.th. 25.65

cut 0.28

residual 25.37

b.th.

cue

residual

b.th.

cut

residual

b.th.

cut

residual

b. tn.

cut

residual

b.th.

cut

residual

b.th.

cut

residual

b.th.

cut

residual

27.83 D.12

6.31 0.12

21.52 0

25.76 0.03

0.81 0.03

24.95 0

23,95

31.56

0

31.56

.34

0

27.93 0.04

0 0.04

27.93 0

32,J6 0-28

0 0.2B

32.16 0

62.58

0

62.53

0.99

Q.47

0.52

0.12

0

0.12

O.0S

0.08

0

4.64

1.70

2.94

0.10

0.10

0

1.26

0.11

1.15

2.6D

0

2.8Q

0.2i

0

0.2b

0.13

0.13

0

0.37

0,37

0

0.03

0,03

0

.05

.05

0

0.03

0.03

0

53.77

15.5*

38,23

66.68

29.B4

36.84

63.23

27.36

35.87

50.22

31.92

18.30

51.07

31.66

19.21

60.44

41.77

18.67

61.74

0

61.74

54.75

0

54.75

58.62

0

53.62

17.20

17.20

0

7.62

7.62

0

10.36

10.86

0

6.26

6,26

0

18.93

18.93

0

11.69

11.69

0

12.36

12.36

0

7.82

7.82

0

5.22

0

5.22

41.26

16.14

25.12

49.02

10.40

33.62

46.66

14.99

31.68

39.32

17.27

22.05

51.69

27.61

24.08

45.65

20.41

25.24

48,23

0

48.23

52.88

0

52.88

51.70

0

51.70

30.03

0

80.03

0.81

0.81

0

0.50

0.50

0

0.24

0.24

0

0.09

0.09

0

0.14

0.14

0

1.21

1.21

0

1.31

1.31

0

1.53

1.53

0

2.11

0

2.11

0.42 0.18

0.35 0.18

0.07 0

0.30

0

0.30 -

3.47 0.07

3.05 D.07

0.42 0

1.90 -

0.75

1.15 -

1.09 1-80

0 1.80

1.09 0

0*02 0.22

0 0.22

0.02 0

4.19 2.10

0 0

4.19 2.10

4.76 33.70

4.76 33.70

0 0

20.25 16.82

20.25 16.82

0 0

11.98 25-28

11.93 25.28

0 0

5.74 13.02

5.74 13.02

0 0

19.24

19.24

0

10.37 8,71

10.37 B.71

0 0

16.59 45.76

16.59 45.76

0 0

1.43 53.32

1.43 53.32

0 0

15.98 43.28

15.98 43.28

0 0

31.67

0

31.67

53.07

0

53.07

41.35

0

41.35

28,86

0

28.86

34.37

0

34.37

34.13

i>

34.13

55.46

□

55.46

6B.31

0

68.31

65.22

0

65.22

96.58

0

96,58

0.48

0

0.48

0.09

0

0.09

0.21

0

0.21

2.60

0

2.60

2.21

0

2.21

2.33

0

2.33

5.10

0

5.10

0.07

0

0.07

0.49

0

0.49

0.46

0

0.46

1.52 -

0

1.52i -

0.24 0.97

0 0

0.24 0.97

0.02 -

0

0.02 -

4.96 0.55

0 0

4.96 0.55

b.th. - before thinning

1 sq. ft/acre » 0.23 sq. in/ha

Acknowledgement AbstractTable of ContentsIntroduction, location and historySite and stand conditions 9n 1965Figure 1 - Sparse foliage and yellow needle color ar characteristic of red pine growing between black walnutFigure 2 - Sparse foliage and dying red pine in walnut plantation on the left contrast sharply with healthy red pine in oak plantation on the rightTreatmentsFigure 3 - Large black walnut knotFigure 4 - CankerFigure 5 - Control plot of field plantation, 1965Figure 6 - Control plot of woodlot plantation, 1965Results and DiscussionTable 1 - Number of trees per acre after 1965 and 1970 thinningsTable 2 - Basal area of hardwood treesFigure 7 - Control plot of field plantationFigure 8 - Heavily thinned plot of field plantation Table 3 - Diameter and height of hardwood trees of average basal area by plot and year of measurmentTable 4 - Diameter and height of the 100 largest hardwood trees per acre by plot and year of measurementTable 5 - Concentration of N, P and K in wlanut leavesSummaryLiterature CitedAppendiciesAppendix 1Appendix 2Appendix 3 - Number of trees per acre by speicies before and after 1965 and 1970 thinningsAppendix 4 - Basal area per acre by species before and after 1965 and 1970 thinnings