Livestock, land use change, and ... - Cornell Universitytiesmexico.cals.cornell.edu/research/documents...R.W. Blake and C.F. Nicholson 133 9 Livestock, land use change, and environmental

R.W. Blake and C.F. Nicholson

133

9

Livestock, land use change, and environmentaloutcomes in the developing world

R.W. Blake1 and C.F. Nicholson2

Departments of Animal Science1 and Applied Economics andManagement2, Cornell University, Ithaca, NY 14853 USA

Demand drivers and linkages

Rapid predicted worldwide growth in demand for animal products to2020, the so-called “next food revolution” in animal agriculture,portends complex interactions among people, biological andgeophysical resources, and economic objectives. Consumer demandfor beef and pork is expected to increase by 2.8% per year, somewhatslower than demand growth for poultry meat (3.1%/yr). Demand fordairy products is predicted to grow fastest, at 3.3%/yr (Delgado etal., 1999). More people with greater per capita incomes, primarilyurbanites in developing countries, are expected to purchase about70% more meat and 90% more milk than they did in 2000. Arestructuring of global food demands is expected: in contrast tocurrent patterns, most (>60%) global production of meat and milkwill be consumed by households in the developing countries (Cranfieldet al., 1998; Delgado et al., 1999). This consumption shift will bringanother major change: the livestock sector would become thedominant value share of global agricultural output. The key driversof this change are income growth, population growth, urbanization,and increased opportunities for trade (Figure 9.1).

This future food demand scenario involves two elements of the so-called “critical triangle” of development (Vosti, 1995), the alleviationof poverty (by increasing food production and food security) and theeconomic growth to achieve it. Correspondingly, greater demandfor products of animal origin signifies a critical developmentopportunity for producers, especially small-scale farmers in developingcountries who rear the majority of the world’s livestock. However,economic and poverty-alleviating objectives also confront competinggoals and environmental costs that constitute the triangle’s thirdelement: factors that sustain, or that may threaten, the environment.For example, demand increases for meat from non-ruminants (poultryand swine) especially signify greater pollution from confinementsystems and more land to produce feed grains, while greater demandfor beef would stimulate more pasture use of land.

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Text Box

Blake, R. W., and C. F. Nicholson. 2004. Livestock, land use change, and environmental outcomes in the developing world. Pages 133-153 (Chapter 9) in Responding to the Livestock Revolution-the role of globalization and implications for poverty alleviation. (Owen et al., eds.). Nottingham University Press, UK.

Livestock, land use change, and environmental outcomes in the developing world

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Selected potential impacts of increased demand for livestock productsare illustrated in Figure 9.1. The key drivers result in additional demandfor livestock products, which increases the profitability of livestockproduction. This, in turn, results in additional land being used forlivestock and a larger global inventory of livestock. The developmentopportunities for smallholders are illustrated by the “growth linkages”loop, which relates an inventory with more animals to higher incomesfor smallholders, whose spending of it generates additional incomefor other groups. In situations where the attractiveness of alternativesis low, increases in smallholder income can also be used to increaselivestock numbers even further (the “livestock assets” loop). More

Figure 9.1.Key drivers of livestock

product demand,stocks of land, andimportant feedbackloops. The dashed

growth linkages loopindicates that

livestock ownershippromotes income

growth for smallholderfarmers in the

developing world. Thesolid livestock assets

loop indicates thatincome growth can

lead to the desire toown more livestock

assets. Theprofitability of

livestock and theirnumbers influence the

conversion of landfrom other uses to

livestock production(grey dashed arrows).

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livestock and land devoted to livestock production have potentialnegative environmental impacts through land conversion (e.g., forestclearing for pastures) and reductions in the productivity of land usedfor livestock, which results in the need for additional land clearing.Management strategies that conserve soil properties and supportefficient nutrient cycling may offset degradation pathways, andincreases in animal and land productivity may reduce the incentivesfor land conversion.

We identified some of the environmental risks, and recuperative effects,of animal agriculture in a recent article (Nicholson et al., 2001) noting,however, that environmental conditions in developing countries willlikely worsen before they might improve (Alexandratos, 1995, withworld population growing daily by about 250,000 people, it may beunrealistic to expect improvement in environmental conditions). Thatarticle focused on the impacts of forest conversion to pasture in LatinAmerica, biological diversity in East Africa, and global greenhousegas emissions from livestock production. This presentationcomplements that previous one, focusing more broadly on theecosystem impacts of conversion of land to agricultural uses. Weconcentrate on systems with ruminant livestock, discuss the linkagesto growth in animal products demand, and identify appropriate policyand research.

A key question is “How can (should) international agriculturalresearchers, the development community, and policy makers supportthe beneficial aspects of the growth in demand for animal productswhile minimizing negative environmental outcomes?” The productivityof land and livestock must be improved in an economically andenvironmentally reasonable way to feed a human population whosegrowth is a primary force threatening Earth systems. Achieving thesegoals involves tradeoffs because win-win outcomes, where theecosystem impacts accompanying livestock-related householdactivities are inherently neutral or favourable, may be realisticallyfew. Thus, a second key question is “Who should pay, directly orindirectly, for changes in agricultural production practices to reduceor mitigate environmental impacts?” Furthermore, the characteristicsof specific situations vary greatly, implying the need for site-specificityin research and policy initiatives. A case in point: whereas pollutionfrom excess nutrients (and microbes) from animal waste is a problemin developed countries, many are the cases in the developing worldwhere too few nutrients, not too many, constrain agriculturalsustainability. For example, reducing the P content of excreta fromswine with dietary phytase helps control P transfers to the environment(e.g., pollution). However, in tropical locations where manure isfertilizer, swine manure with normal high P content is premium fertilizer,especially for low-P soils or crops with a high requirement. Hence,

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specific cases and system complexity demand specific information,research knowledge, and policy interventions. Generalrecommendations, therefore, may be inappropriate or ineffective.Also, agricultural research and development policies alone may beinsufficient to resolve these problems if dominant “root causes” lieelsewhere. For example, population growth and increases in percapita resource use may prove to be far more significant anenvironmental problem than land conversion from livestock (Meadows,2002). However, projections of population growth and assessmentsof its impacts differ. Therefore, we focus on examination of currentevidence about impacts of livestock in the shorter run, withoutendorsing a particular view about the future in the longer term (50-100 yr).

The remainder of this chapter consists of three sections. The firstsection summarizes the environmental and ecological impacts of landconversion, emphasizing change from natural habitats to agriculturaluse (but also notes that intensification of existing agricultural systemsinvolves similar effects and mechanisms). The second section discussesthe environmental impacts and tradeoffs for the case of expandedbeef production in the western Brazilian Amazon. This casedemonstrates the desirability of site-specificity for research and policydesign and the potential usefulness of systems modelling for ex anteevaluation of alternative interventions. The final section concludeswith an overview of research and policy recommendations, notingthe potential complexity of using agricultural technologies to reduceenvironmental impacts of livestock production.

Ecological and environmental impacts of land conversion

Relationships stemming from land conversion

Increased livestock production has a number of potential negativeenvironmental consequences. Among these, the conversion of landfrom natural habitats to agricultural uses more generally, particularlyin tropical forest areas, has been a key cause for concern for the pastfew decades. The key relationships among livestock production, landuse change, and environmental outcomes are shown in Figure 9.2.Land use conversion from forest to pasture is driven by incentives forlivestock production (which are increased by livestock demand), limitedalternatives to livestock production in these areas, and perhaps moreimportantly, economic inequality and poverty that create incentivesfor forest clearing by migrants. Land is also cleared for cropping,and conversion of land from pasture to crops (and vice versa;Nicholson et al., 1995). Clearing forest land reduces biodiversityand ecosystem services (e.g., pollination, pest control, flood controland water release). Current pasture management practices often

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Figure 9.2.Relationships among

livestock, land usechange, and

environmentaloutcomes. Dark greyarrows indicate key

environmental orecological impacts.

Light grey arrowsindicate effects on

conversion of land topasture. Dashedarrows indicate

effects related to soilnutrient cycling. Thepolarity of individual

effects is indicated aspositive (+) or

negative (-). [CL=cropland; GG=greenhouse

gases;GGC=greenhouse gas

concentration;P=pasture; PL=pasture

land].

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result in land degradation, which results in the need for more forestclearing, and pasture burning to promote regrowth and nutrient cyclingleads to additional forest losses from accidental fires. The connectionbetween land use change and greenhouse gas emissions is alsoindicated. Forest clearing (often through burning) releases largeamounts of CO

2 to the atmosphere, and greater livestock numbers

also increase greenhouse gas emissions. At the same time, the abilityof terrestrial ecosystems to absorb gases (especially CO

2) is reduced

by forest clearing.

The ecological literature provides quantitative estimates of themagnitude of some of these impacts and their importance. Accordingto some observers, human demands on nature already may haveexceeded regenerative capacity of the biosphere, which may bringan end to rapid agricultural expansion within 50 years (Tilman et al.,2001a; Wackernagel et al., 2002). “Just as demand for energy isthe major cause of increasing atmospheric greenhouse gases, demandfor agricultural products may be the major driver of future non-climaticglobal change” (Tilman et al., 2001a). Various forecasts, differing indegree but not in direction (Laurance, 2001; Laurance et al., 2001;Tilman et al., 2001a; Vitousek et al., 1997), anticipate importantlosses of habitat, biodiversity and ecosystem services by transformingmore land to feed humankind, especially in Latin America and sub-Saharan Africa. These environmental modifications, involving greaterinputs of N, P, water and pesticides, can affect economic returns in avariety of agricultural systems, including high input-output animalmonoculture, integrated crop-livestock systems (e.g., smallholders),and modest-performance extensive systems (e.g., grazing). However,the extent of these economic effects in both the long term and theshort term often is not well documented or acknowledged. Generalimpacts of land conversion described in the literature include nutrientloading, agrochemical pollution, acidification, salinisation,eutrophication of surface water, emissions of greenhouse gases, andirreversible species extinctions. For livestock production systems inthe developing world, greenhouse gas emissions, nutrient losses tothe environment, and species extinctions are of greatest importance.Furthermore, substituting pastures or crops for forest cover increasesalbedo (the ratio of reflected to incident light), which may reduceprecipitation and increase temperatures (Vitousek et al., 1997). Theremainder of this section focuses on the relationships between landuse, habitat loss and fragmentation and biodiversity losses, andagroecological options for producing food and ameliorating the long-term environmental costs of doing so.

Habitat loss and fragmentation

Simplifying natural ecosystems (and biogeochemical cycles of C, N

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and P) with agricultural uses initiates processes that lead to biomasslosses and species losses and substitutions: The abundance ofbiodiversity is directly related to the abundance of biomass. We notedin our previous paper that relationships between forest conversionand biodiversity have often been oversimplified, and that the dynamicsbetween pasture, trees and forest remnants are complex. However,conversion of forest to pastureland is an important source ofbiodiversity loss from changes in regional climate, nutrient dynamicsand biotic exchange, which implies the food revolution in animalagriculture could increase these losses. Burning is a principal pathwayfor initial forest clearing that releases nutrients stored in above-groundbiomass. However, routine pasture management in many parts ofLatin America involves periodic burning to promote pasture regrowth,control weeds, and release nutrients from senescent plant biomass.Unfortunately, about 40% of these pasture and slash fires escape toadjacent areas (Kauffman et al., 1998). Burning practices resultedin about 17 million hectares of uncontrolled fires in Indonesia andLatin America in 1998. The estimated $19 to $25 billion cost ofthese fires (Cochrane, 2001), presumably mostly in sacrificed forestproducts, may greatly undervalue total losses also in habitat, speciesand atmospheric load. More light through more penetrable burntforest canopy causes warming, which increases water losses andmakes forests more fire-prone. In addition to destruction of habitat,burning pastures releases large quantities of C to the atmosphere.Therefore, pasture management in which less land is burned lessfrequently would protect forests and the services they provide.

Lost and fragmented habitats make it more difficult for plants andanimals to meet needs and survive environmental vagaries (Laurance,2001; Sala et al., 2000). Although pollen flow could partlycompensate fragmentation losses in certain cases, it requires thatwelfare and behavioural (spatial) responses of pollinators are assured(White et al., 2002). Also, fragmented forest is more susceptible tofire from ‘vegetation breeze’, where clearings large and small drawmoisture from the forest, substituting it with dry air. Dried forest edgesare more likely to ignite when nearby pastures are burned (Lauranceet al., 2002).

Unfortunately, besides altered land use “the strength of interactionsamong drivers in their effects on biodiversity is virtually unknown”(Sala et al., 2000). These interactions are poorly understood in lowas well as high rainfall ecosystems. Zonal effects of cattlepost systemsin the semi-arid Kalahari (Botswana) produce an environmentaltradeoff between vegetation sacrificed and the amount of rangelandbiodiversity that is retained (Perkins, 1996). Supported by boreholewater, these dynamic systems rely on herd mobility and flexibility in amanner similar to wildlife. Water availability increases the area that

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can be used by cattle but results in severe land degradation due toexcessive nutrient loading within 50 m of watering locations. Thismodest sacrifice in habitat permits cattlepost managers to makeproductive use of the remaining rangeland without significantdegradation of that resource, which is now known to respondfavourably (e.g., greater plant survival and productivity) to continuousgrazing pressure and unfavourably to the lack of it (Oba et al., 2000).In fact, land productivity of the cattlepost system exceeded that fromsubsidized commercial beef systems when all herd outputs (milk, beef,and draft power) were accounted (Perkins, 1996).

Cascading effects on species shifts and biodiversity losses

Transforming lands with marginal fertility to agriculture can have alarge global effect because these locations sustain ecosystems ofhigh diversity. About 18% of mammals, 11% of birds and 8% ofplant species may currently be at risk of extinction from land conversion(Vitousek et al., 1997), which implies significant agroecosystem lossessuch as wild genes for resistance to plant pests and disease, pollinationby birds, insects, bats and other mammals (from neighbouringecosystems), and pest outbreak control by predators (Tilman, 1999).Forest disturbance is one pathway that adversely affects understoryinsectivores, especially birds with limited dispersal ability whosevulnerability is heightened to forest edge effects, isolation and randomevents (Sekerciouglu et al., 2002). Species least affected are thoseable to utilize clearings. Biological invasions also reduce speciesdiversity and increase pest losses in crops and livestock (Pimentel etal., 2000). Scarce soil nutrients are more completely utilised in highdiversity systems, which constitutes a barrier to invading species(Tilman, 1999). Conversely, unconsumed nutrients may favourpathogens and pests, which may be a consequence of indiscriminateor uncalibrated fertilization of food and forage crops. For example,high soluble N in fertilized plants can invite larger populations ofsap-feeding insects (Matson et al., 1997), a phenomenon that mayalso apply to forage grasses. Differing from past recommendationsrelying on more fertilizer to produce more rice, today growers aresometimes urged to moderate their N use to reduce risk of yieldlosses from pest outbreaks. High external nutrient inputs on arablelands in rainy climates and erosion losses in overstocked arid landsalso lead to less diversity. Increases in farm land have shrunk habitats,populations of non-domesticated animal species and their range ofdispersal. This process imposes selection pressures against largespecies with low dispersal potential, which increases threats (e.g.,weeds, pathogens and competitive microbes) to the environment andto agriculture (Western, 2001).

Species extinction is partly governed by the interaction betweendispersal ability, habitat loss and climate change. Greater rainfall

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variability affects habitat and climate change and has resulted inpopulation fluctuations and extinction of butterflies (McLaughlin etal., 2002). Possibly exacerbated by substitution with grasses, larvaemortality rates increased from shorter overlap with the required plants.Environmental bottlenecks also invoke biological mechanisms ofspecies loss. Predisposition to extinction is increased by inbreedingwhen the effective population size becomes small and insular, whichresults in losses of alleles with large effects on fitness and survival(Keller and Waller, 2002). Inbreeding depresses birth rate, birthweight, offspring survival, and resistance to disease and other stressors(e.g., predators), which makes individuals more likely to perish fromvagaries of the environment. Less heterozygous sheep had moreparasitism and were less likely to survive untreated helminthicinfestation than more heterozygous individuals (Keller and Waller,2002), an important consequence for producers who cannot affordchemical control.

Mitigating biodiversity losses requires clear understanding of themechanisms in each case. On a global scale, this means a set ofmanagement portfolios matched efficaciously to biological and socio-economic needs by eco-region (Sala et al., 2000). Productivity anddiversity may be enhanced by complementarities and net favourableinteractions among species, including resistance to pathogens andinvaders, especially where nutrients are scarce (Western, 2001).Cropping with a species mixture may be useful (Tilman, 1999). Thisstrategy is used by crop-livestock farmers in Ethiopia’s low-rainfallHarar highlands (Kassa et al., 2002), who densely sow maize andsorghum and selectively thin maize (sorghum) for forage if rainfall islow (high). Species complementarity and niche differentiation, forexample from a mixture of forage genotypes, could exploit warm/cool and rainy/dry seasons, and deep/shallow soil nutrient profiles.

Agroecological options: given where we are, what can we do?

In summary, an important agroecological goal in the long-term is toassure sufficient land and resources for survival of most species(Vitousek et al., 1997). This requires learning how ecosystems interactwith, and recover from, environmental disturbances, includingagriculture. In addition to converting less land to agriculture, it alsomeans curtailing the cascade of interactions on habitats, speciesextinctions and complementarity losses, lost ecosystem services, andnutrient stocks (e.g., for food production, diversity, barriers to pestsand pathogens, waste control). Western (2001) offered usefulprinciples (Table 9.1) for reducing these environmental costs. Basedon this guidance, a nutrient management research portfolio shouldaddress: 1) effective nutrient cycling between soils, plants and animals;2) improved nutrient use efficiencies of plants and animals; 3)

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improved management of nutrient stocks and soil fertility; and 4)alternative uses of grazing land, especially in a more diversifiedagriculture that meets economic needs of producers. Otherconsiderations are to recruit ecosystem services from other speciesby bridging habitat fragments with multi-use land buffers and corridors(e.g., along fence lines on pasture landscape), to plan agriculturewith less land fragmentation and more ecosystem types with biodiversityhot spots preserved, the judicious use of agrochemicals and manure,fallow management (e.g., cover crops), development of productivecrops with lower requirements for water, nutrients and pesticides, andintegrated pest and pathogen management. However, achievingoutcomes that are more environmentally sound often will requireeconomic incentives, especially for small- and medium-sized farmerswho are our key environmental stewards (Pinstrup-Andersen, 2001).The need for economic incentives raises the question of the politicalfeasibility for successful implementation of these strategies on asufficiently large scale to have notable impact.

Maintain or multiply Minimize Mimic

Species richness, structural Erosion, nutrient Natural processessymmetry, key species/ losses and in productionfunctional groups pollution cycles

emissions(e.g., fire)

Internal regulatory Landscapeprocesses and interactions simplification(e.g., predator-prey)

External diversifying forces Landscapehomogenisation

Large habitat areas andspatial linkages betweenecozones

Ecological gradients andecozones

Pasture-based cattle production in Brazil’s arc of deforestation

The foregoing discussion of impacts of land use change and potentialactions is useful, but can be complemented by a discussion of impactsand responses for a specific area. Land use change and policy in theBrazilian Amazon, a topic of current debate (Laurance et al., 2001;2002), has been of great concern for at least the past two decades,and illustrates many of the general concepts identified above. Thus,

Table 9.1.Principles for

conservingecosystem

processes (fromWestern, 2001).

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we use results from studies of dual-purpose (milk-beef) and beef cattlesystems in the Brazilian Amazon to discuss the potentials and limitationsof modifying livestock production systems to achieve more desirableenvironmental outcomes.

The Amazon region of Brazil is essential to global biodiversity, toclimate and regional hydrology, and to C stores by harbouring about40% of the world’s tropical rainforest. This region is also home toabout one-fourth of the national herd of about 170 million cattle,which is currently reared extensively on approximately 43 millionhectares. Forest losses are especially high in the four-state “arc ofdeforestation”, including the westernmost Acre State, and could reach5000 km2/yr (Cochrane, 2001). This transformation is driven bypopulation growth, logging and mining, spatial effects of development(e.g., roadways), and fire. Current trends suggest more habitatfragmentation, less rainfall from less evapo-transpiration andsequestered atmospheric moisture from smoke, higher land surfacetemperatures, species losses, and heightened risk of forest fires abettedby the drying effect of vegetation breeze (Laurance et al., 2001; 2002).Although widespread pasture degradation is well documented in theeastern Amazon, the farm management practices (e.g., stocking rates,soil-plant nutrient relationships, burning frequencies) causing it havenot been adequately studied. Thus, it is currently unknown to whatextent alternative management would control degradation losses (and,therefore, reduce pressure for additional forest clearing).

To reduce environmental losses, Laurance and co-workers (2001)favour farm livelihoods earned from agroforestry and perennialcropping over “fire-maintained cattle pastures and slash-and-burnfarming.” Of course, these alternatives need to be economicallyattractive to be adopted, and the available evidence suggests limitedpotential (Vosti and Valentim, 1998). Alternatively, more intensivecattle production has been proposed to improve economic returns tolabour and land while reducing deforestation pressure. However,greater profits from more intensive management (e.g., more beefand milk from more dietary inputs and labour) may provide incentivesfor additional land clearing. Pasture and cattle activities in Acre wereestimated to be more profitable than other alternatives, which impliedeconomic incentives to clear more forest (Carpentier et al., 2000).Clearing was influenced by labour supply and access to markets.

Recent studies explored soil-plant-animal nutrient relationships, milkand beef potentials, and economic constraints of pasture-based cattlesystems in Acre (the Western Amazon), where large fire-managedpaddocks are lightly stocked with animals not differentiated bynutritional requirements. Findings indicated relatively low nutrientexports in animal products of 6 kg N/ha and 3 kg P/ha (compared to

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rice, beans or coffee crops) from farms with two 450-kg animal unitsper hectare (Rueda et al., 2004). In contrast to studies in the EasternAmazon, pasture productivity has been maintained for two decades.This relative longevity may result from better soil characteristics thanelsewhere in Amazonia, but also from low stocking, which results inmore-than-adequate pasture biomass availability, substantial nutrientsrecycled from leaf litter and less soil compaction. This evidencesupports the idea that pasture management may play a key role insystem sustainability. It also suggests there is potential for positiveoutcomes from research on alternative practices (and, in some cases,reclamation of degraded lands) for other parts of Amazonia.

The current cattle production system in the Western Amazon appearssustainable. However, improved access to beef markets in Lima,Peru and the Pacific region (through a recently completed highway)could create incentives for increased beef production in the region,implying that more intensive production systems may be needed tolimit the ultimate extent of additional forest clearing. Substantialproductive potential was identified for application of external nutrientsto pasture to increase stocking rates and offtake. With herd nutritionbased on accurate predictions of nutrients supplied by forages andrequired by animals (Tedeschi et al., 2002), this translated to greaternet economic returns from labour-intensive (i.e., potentially landsaving) technologies to produce beef (but was not profitable for milk),and not by improving individual performance by bettersupplementation of diets (Rueda et al., 2003). Although more labourwould be required, beef production through judicious fertilization ofgrass-legume pastures and higher stocking rates may improve farmincomes and slow the rate of forest clearing.

However, the long-term dynamics of this intensification strategy arenot known. Higher stocking rates imply shifts in the pools of nutrientsto recycle from plant litter to readily decomposable animal excreta(Figure 9.3). To explore the potential impacts, a systems modellingapproach can be useful. In a conceptual systems model, forageproductivity and residual environmental health are represented asfeedbacks among stocks and flows of four nutrient sources, soil,available pasture (forage) biomass, decaying pasture biomass, anddecaying manure. The grazing-manure management pathway isespecially important to herd productivity, external nutrient demand,and productivity and pasture health outcomes. Proper land allocationsof manure through herd grazing management can reduce fertilizerrequirements and maintain soil nutrient stocks, which supply plantrequirements for growth. A key research question is the extent towhich external nutrient inputs (e.g., mineral fertilizers) are required tosustain this system. Better knowledge of the sizes of the various nutrientpools and the rates affecting them (availability) would provide

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Figure 9.3.Nutrient dynamics in the

pasture-based cattlesystem of the Western

Amazon of Brazilshowing key nutrient

pools and linkagesbetween them. An

increase in animals perland area increases the

grazing rate, thusdecreasing decaying

pasture biomass withgreater nutrient cycling

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nutrient stocks and flowrates.

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information crucial to more intensive management of the Acreproduction systems. However, it is again worth noting that beefdemand is only one of several factors affecting land transformationand alternative agricultural technologies are unlikely to fully addressits root causes (Nicholson et al., 1995; 2001).

Although additional studies to better understand the dynamics ofnutrient stocks in the Western Amazon can facilitate better responsesto increased market access for beef production, available informationsuggests that certain strategies may help reduce negativeenvironmental impacts. The recommendations in Table 9.2 emphasizeopportunities for better integrated nutrient management under currenteconomic conditions.

Pastures and animals Biodiversity

Harvest pasture nutrients by intensive Design and build throughgrazing; avoid burning pasturelands a bridge

network of fragmentation-Herd nutrition based on accurate ameliorating, diversifiedpredictions of forage quality and forest blocks andanimal nutrient requirements corridors with income-

earning potential (e.g.,Group animals in paddocks natural barrier fences) toaccording to their nutrient preserve wildlife and re-requirements generate ecosystem

servicesTitrate stocking and herd size andprovide drinking water to assureeffective distribution of excreta acrossthe landscape (to promote widespreadnutrient recycling)

Fertilize in accordance with thenutrients extracted and recycledfrom excreta

Evaluate and utilize multi-speciesportfolios of grasses and legumes

Focus management on herdreproduction and herd performance, notindividual performance

Limitations of the technology toolbox

To what extent can the development of agricultural technologies forcattle production systems in the Amazon region reduce the pressure

Table 9.2.Agro-ecosystem

managementopportunities forcattle systems in

Acre, Brazil.

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for additional forest clearing? The multiple causes of forest clearinghave already been mentioned, and these may, in fact, dominateattempts to increase (or maintain) the productivity of land and livestock.However, a more subtle challenge is that technologies that increaseproductivity may actually increase incentives to clear land. As Ruedaand co-workers (2003) noted, profitable technologies that increaseor maintain productivity of beef can reduce the need for land.However, if technologies are sufficiently profitable, they may result inincentives for additional forest clearing, so as to apply the new (moreprofitable) technology to a broader land base. The nature of thischallenge is illustrated in Figure 9.4. Technology use depends on anumber of factors, including the expected economic returns fromdoing so. If the technology increases the profitability of beefproduction, it creates incentives to clear additional land. If thetechnology is labour-intensive, and labour (for hire) is limited in theregion, this may limit the impact of increased profitability on forestclearing (Angelsen and Kaimowitz, 2001). In the long-run, however,if the new technology is profitable enough, wages can rise and inducegreater migration to the area, which will increase the availability oflabour and, therefore, forest clearing. These basic principles applybroadly to many technological options, including those cited above.The basic result is that developing livestock production technologiesthat are profitable in the short run and do not exacerbate land usechange is a major challenge.

Information needs and recommendations

More understanding is needed about the interaction of agriculturalpractices with environmental and ecological outcomes to developpractices that avoid further deterioration and restore accumulateddamages. Models predicting habitat loss from conversion toagriculture and land degradation indicate that “a pool of species willeventually become extinct unless the habitat is repaired or restored”(Dobson et al., 1997). Studying restoration processes of degradedland would build understanding about ecological communities andagro-ecological function. Priority sites include ecosystems whereagriculture was short-lived, such as forests cleared in the EasternAmazon. Integrated agro-ecological strategies include improvednutrient management, illustrated above for the Western Amazon.Complementary strategies include bridging (restoring) forest fragmentswith hospitable fence line corridors and windbreaks of native speciesto facilitate wildlife dispersals and ecosystem services (Sekercioglu etal., 2002; Tilman et al., 2001b). Investments are needed in productiveand environmentally friendly technologies, especially for small- andmedium-sized farmers who are equally efficient as large-scaleoperators and wise stewards of the environment. The technologytoolbox should include new innovations based on external inputs and

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Use

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Figure 9.4.Relationships

between technologyadoption and forest

clearing. Dashedpathways indicatekey relationships

between profitabilityand clearing. Heavy

solid pathwaysindicate the

relationshipsbetween

productivities ofland, labor and

animals and clearing.Grey pathways

indicate feedbacksbetween productivity,

profitability andtechnology adoption.

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agroecological approaches that are sensitive to supplies of locallabour, organic inputs, improved knowledge and farm management(Pinstrup-Andersen, 2001).

Despite incomplete information about the best animal agricultureresponses to global food demand drivers, and ways to motivate suchimplementations, short-term actions as well as research investmentsare needed. It is unrealistic that rural households can (or should)fully bear the burden of environmental costs because win-winopportunities are probably limited. Thus, the main challenge involvesconnecting existing knowledge about how agro-ecosystems functionto the effectiveness of candidate interventions in specific situations.There are essentially five types of interventions that can be undertaken.These include financial incentives provided to farm households topromote desirable ecosystem outcomes (or reductions in subsidiesfor harmful activities); research to develop profitable technologieswith minimal undesirable environmental impacts (or that arerestorative); prohibition or restrictions on harmful activities with effectiveenforcement, and education for stakeholder groups about theecological and environmental consequences (negative, positive) oftheir actions. In certain cases, innovative institutional arrangements(e.g., modification of land use rights, access to credit or banking thatreduces dependence on livestock assets) will also be necessary ordesirable. It is likely that some combination of these will be mosteffective. Land tenure, taxation and economic policies are othermechanisms for mitigation and restoration; and better communicationis also needed so that science is better utilized in policy making(Fernandez, 2002).

To examine more fully the effectiveness of potential interventions, itwill be helpful to integrate existing disciplinary knowledge intoconceptual or quantitative simulation models. Modelling ofagricultural systems has become an important way to assess thepotential for policy interventions to prevent or mitigate environmentalconsequences (Thornton and Herrero, 2001; Heerink et al., 2001).One general approach that can be usefully employed in this contextis system dynamics (SD), a broadly applicable systems-based approachto problem solving (Sterman, 2000). Using SD, problems areexpressed as a feedback (stock-flow) model that provides insightsabout how a problem behaviour developed over time and aboutwhich interventions or policies can provide a lasting solution to theproblem. System dynamics is most appropriate for problems that aredynamically complex (evolve over time, are non-linear and governedby feedback), are long-term in nature, can be described by a relativelysmall set of “reference mode” behaviours observed in the real world,and can be described by flow processes (Vennix, 1996). The SDapproach permits conceptual and quantitative modelling of dynamic

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problems, and has been previously applied to land degradationprocesses in sub-Saharan Africa (Brontkes, 2001). For successfulapplication of these methods, it will be important to provide incentivesto researchers from various disciplines, policy makers, developmentorganizations, and farm households to work together to gain a broadperspective on the nature of both the problems and potential solutions.Because values, that is, the ultimate objectives to be achieved inresponse to the changes wrought by increased livestock demand, arelikely to differ among the different disciplines (e.g., animal scientists,ecologists, economists), discussions of these values will be animportant component of successful multidisciplinary research efforts.

Acknowledgements

We thank the following people for reading an earlier draft of thisarticle and for their helpful suggestions to improve it: Duane Acker,G. Eric Bradford, Rod Heitschmidt and David Pimentel.

References

Alexandratos, N. (ed.) (1995). World Agriculture towards 2010: AnFAO study. Chichester, UK: Food and Agriculture Organizationof the United Nations and John Wiley and Sons Ltd.

Angelsen, A. and Kaimowitz, D. (2001). When does technologicalchange in agriculture promote deforestation? In: Tradeoffs orsynergies? Agricultural intensification, economic developmentand the environment. Edited by D.R. Lee and C.B. Barrett. CABInternational Wallingford, UK, pp. 89-114.

Brontkes, T.S. (2001). Agricultural prices and land degradation inKoutiala, Mali: A regional simulation model based on farmer’sdecision rules. Economic policy and sustainable land use: Recentadvances in quantitative analyses for developing countries.Edited by N. Heerink, H. van Keulen and M. Kuiper. Physica-Verlag, Heidelberg, pp.151-168.

Carpentier, C., Vosti, S.A. and Witcover, J. (2000). Intensifiedproduction systems on western Brazilian Amazon settlementfarms: could they save the forest? Agriculture Ecosystems andEnvironment 82:73-88.

Cochrane, M. (2001). In the line of fire. Understanding the impactsof tropical forest fires. Environment 43:28-38.

Cranfield, J.A.L., Hertel, T.W., Eales, J.S. and Preckel, P.V. (1998).Changes in the structure of global food demand. AmericanJournal of Agricultural Economics 80:1042-1050.

Delgado, C., Rosegrant, M., Steinfeld, H., Ehui, S., and Courbois,C. (1999). Livestock to 2020: The next food revolution. Food,Agriculture and Environment Discussion Paper 28, InternationalFood Policy Research Institute (IFPRI), Washington, DC, USA.

09-Blake-.p65 3/4/2004, 9:01 AM150


151

Dobson, A.P., Bradshaw, A.D. and Baker A.J.M. (1997). Hopes forthe future: Restoration ecology and conservation biology. Science277:515-522.

Fernandez, R.J. (2002). Do humans create deserts? Trends in Ecologyand Evolution 17:6-7.

Heerink, N., Kuyvenhoven, A. and van Wijk, M.S. (2001). Economicpolicy reforms and sustainable land use in developing countries:issues and approaches. Economic policy and sustainable landuse: Recent advances in quantitative analyses for developingcountries. Edited by N. Heerink, H.van Keulen and M. Kuiper.Physica-Verlag Heidelberg, pp. 1-20.

Kassa, H., Blake, R.W. and Nicholson, C.F. (2002). The crop-livestocksubsystem and livelihood dynamics in the Harar Highlands ofEthiopia. In: Responding to the increasing global demand foranimal products - Programme and Summaries. Internationalconference organised by the British Society of Animal Science,American Society of Animal Science and Asociacion Mexicanade Produccion Animal, held at the Universidad Autonoma deYucatan, Merida, Mexico, 12-15 November, 2002. BritishSociety of Animal Production, Penicuik, UK, pp. 74-75.

Kauffman, J.B., Cummings, D.L. and Ward, D.E. (1998). Fire in theBrazilian Amazon. 2. Biomass, nutrient pools and losses in cattlepastures. Oecologia 113:415-427.

Keller, L.F. and Waller, D.M. (2002). Inbreeding effects in wildpopulations. Trends in Ecology an Evolution 17(5):230-241.

Laurance, W.F. (2001). Future shock: forecasting a grim fate for theEarth. Trends in Ecology and Evolution 16:531-533.

Laurance, W.F., Cochrane, M.A., Bergen, S., Fernside, P.M.,Delamonica, P., Barber, C., D’Angelo, S. and Fernandes, T.(2001). The future of the Brazilian Amazon. Science’s CompassPolicy Forum, 19 January, 291:438-439.

Laurance, W. F., Powell, G. and Hansen, L. 2002. A precariousfuture for Amazonia. Trends in Ecology and Evolution 17:251-252.

Matson, P.A., Parton, W.J., Power, A.G. and Swift, M.J. (1997).Agricultural intensification and ecosystem properties. Science277: 504-509.

Meadows, D.M. (2002). Reflections on the dynamics of growth. Paperpresented at the Annual Meeting of the System Dynamics Institute,June 4, 2002, Montebello, Quebec.

McLaughlin, J.F., Hellmann, J.J., Boggs, C.L. and Ehrlich, P.R. (2002).Climate change hastens population extinctions. ProceedingsNational Academy of Science 99:6070-6074.

Nicholson, C.F., Blake, R.W., Reid, R.S. and Schelhas, J. (2001).Environmental impacts of livestock in the developing world.Environment 43:7-17.

Nicholson, C.F., Blake, R.W. and Lee, D.R. (1995). Livestock,

09-Blake-.p65 3/4/2004, 9:01 AM151


152

deforestation, and policy making: Intensification of cattleproduction systems in Central America revisited. Journal of DairyScience 78:719-734.

Oba, G., Stenseth, N.C. and Lusigi, W.J. (2000). New perspectiveson sustainable grazing management in arid zones of sub-Saharan Africa. BioScience 50:35-51.

Perkins, J.S. (1996). Botswana: fencing out the equity issue. Cattlepostsand cattle ranching in the Kalahari Desert. Journal of AridEnvironments 33:503-517.

Pimentel, D., Lach, L., Zuniga, R. and Morrison, R. (2000).Environmental and economic costs of nonindigenous speciesin the United States. BioScience 50:53-62.

Pinstrup-Andersen, P. (2001). Feeding the world in the new millennium:Issues for the new US administration. Environment 43:22-31.

Rueda, B., Blake, R.W., Fernandes, E., Nicholson, C.F. and Valentim,J.F. (2004). Soil, plant and cattle nutrient pools on pastures ofthe western Amazon of Brazil. Agriculture, Ecosystems andEnvironment (submitted).

Rueda, B., Blake, R.W., Nicholson, C.F., Fox, D.G., Tedeschi, L., Pell,A.N., Fernandes, E., Lee, D.R., Valentim, J.F. and da Costa, J.(2003). Production and economic potentials of cattle in pasture-based systems of the western Amazon region of Brazil. Journalof Animal Science 81:2923-2937.

Sala, O.E., Chapin III, F.S., Armesto, J.J., Berlow, E., Bloomfield, J.,Dirzo, R., Huber-Sanwald, E., Huenneke, L.F., Jackson, R.B.,Kinzig, A., Leemans, R., Lodge, D.M., Mooney, H.A., Oesterheld,M., Poff, N.L., Sykes, M.T., Walker, B.H., Walker, M. and Wall,D.H. (2000). Global biodiversity scenarios for the year 2100.Science 287:1770-1774.

Sekercioglu, C.H., Ehrlich, P.R., Daily, G.C., Aygen, D., Goerhring,D. and Sandi, R.F. (2002). Disappearance of insectivorous birdsfrom tropical forest fragments. Proceedings National Academyof Science 99:263-267.

Sterman, J.D. (2000). Business dynamics: Systems thinking andmodeling for a complex world. McGraw-Hill, USA.

Tedeschi, L.O., Fox, D.G., Pell, A.N., Lanna, D.P.D. and Boin, C.(2002). Development and evaluation of a tropical feed libraryfor the Cornell Net Carbohydrate and Protein Model. ScientiaAgricola 59(1):1-18.

Thornton, P.K., and Hererro, M. (2001). Integrated crop-livestocksimulation models for scenario analysis and impact assessment.Agricultural Systems 70:581-620.

Tilman, D. (1999). Global environmental impacts of agriculturalexpansion: The need for sustainable and efficient practices.Proceedings National Academy of Science 96:5995-6000.

Tilman, D., Fargione, J., Wolff, B., D’Antonio, C., Dobson, A.,Howarth, R., Schindler, D., Schlesinger, W.H., Simberloff, D. and

09-Blake-.p65 3/4/2004, 9:01 AM152


153

Swackhamer, D. (2001a). Forecasting agriculturally driven globalenvironmental change. Science 292:281-284.

Tilman, D., Reich, P.B., Knops, J., Wedin, D., Mielke, T. and Lehman,C. (2001b). Diversity and productivity in a long-term grasslandexperiment. Science 294:843-845.

Vennix, J.A.M. (1996). Group model building: Facilitating teamlearning using system dynamics. John Wiley and Sons,Chichester, UK.

Vitousek, P.M., Mooney, H.A., Lubchenco, J. and Melillo, J.M. (1997).Human domination of Earth’s ecosystems. Science 277:494-499.

Vosti, S.A. (1995). Sustainability, growth, and poverty alleviation:Research and policy issues for tropical moist forests. Agricultureand environment: Bridging food production and environmentalprotection in developing countries. Edited by A.S.R. Juo and R.D. Freed. pp. 207-227. Special Publication 60, Soil ScienceSociety of America.

Vosti, S.A. and Valentim, J. (1998). Foreward. In: Cattle, deforestationand development in the Amazon: An economic, agronomic andenvironmental perspective. (M.D. Faminow, Ed.) CABInternational, Wallingford, UK, pp. vi-viii.

Wackernagel, M., Schulz, N. B., Deumling, D., Linares, A. C., Jenkins,M., Kapos, V., Monfreda, C., Loh, J., Myers, N., Norgaard, R.and Randers, J. (2002). Tracking the ecological overshoot ofthe human economy. Proceedings National Academy of Science99:9266-9271.

Western, D. (2001). Human-modified ecosystems and future evolution.Proceedings National Academy of Science 98:5458-5465.

White, G. M., Boshier, D. H. and Powell, W. (2002). Increased pollenflow counteracts fragmentation in a tropical dry forest: Anexample from Swietenia humilis Zuccarini. Proceedings NationalAcademy of Science 99:2038-2042.

09-Blake-.p65 3/4/2004, 9:01 AM153


154

09-Blake-.p65 3/4/2004, 9:01 AM154

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