Livestock and environment: potential for complementarity

R. Mearns

The author is a Fellow at the Institute of Development Studies, University of Sussex, Brighton BN1 9RE, UK. Tel. +44 1273 678774; fax: +44 1273 621202/691647; e-mail: [email protected] . Note: This article is the first part of a revised paper originally prepared for the World Bank/FAO workshop on Balancing Livestock and the Environment, held in Washington, DC, 27-28 September 1996, as an associated event to the Fourth World Bank Conference on Environmentally Sustainable Development. The author is grateful for the financial support of FAO and the World Bank and for comments made by Craig Bullock, Cees de Haan, Simon Maxwell, Ian Scoones, Dennis Sheehy, Brent Swallow, Jeremy Swift, workshop participants and anonymous reviewers. None of these individuals or institutions is responsible for any errors which may remain. The second part of the paper will appear in the next issue of World Animal Review, to be published later this year.

�LEVAGE ET ENVIRONNEMENT: UNE COMPL�MENTARIT� POTENTIELLE

Le choeur de ceux, qui dans le monde entier reprochent aux �leveurs de se livrer � une activit� non respectueuse de l'environnement, s'amplifie. La simple association des termes �b�tail� et �pays en d�veloppement� est imm�diatement assimil�e dans l'esprit de bien des gens � surp�turage, d�sertification et d�boisement. Or, l'impact de la production animale sur l'environnement varie consid�rablement selon les diff�rents syst�mes de production, les possibilit�s offertes et les contraintes, et selon le contexte institutionnel et politique. Cet article, qui porte essentiellement sur les syst�mes pastoraux extensifs et sur les syst�mes int�gr�s agriculture-�levage, �tudie un aspect moins bien document�, celui des effets externes positifs que l'�levage peut aussi avoir sur l'environnement. La production animale peut, par exemple, contribuer � l'am�nagement durable des parcours et � la conservation de la faune et autres formes de biodiversit�, am�liorer la fertilit� du sol et le cycle des substances nutritives, et valoriser directement certains paysages aux yeux d'autres utilisateurs. Un autre article, � para�tre dans le prochain num�ro de cette revue, montre comment accro�tre, au moyen d'instruments politiques, la participation des multiples usagers du milieu naturel, �leveurs compris, aux b�n�fices �cologiques.

GANADERIA Y MEDIO AMBIENTE: POSIBILIDADES DE COMPLEMENTARIEDAD

Los productores pecuarios son objeto de cr�ticas crecientes en todo el mundo, aduciendo que la producci�n ganadera es perjudicial para el medio ambiente. Basta mencionar los conceptos de ganado vacuno y pa�ses en desarrollo al mismo tiempo para que muchos los asocien con los temas del sobrepastoreo, la desertificaci�n y la deforestaci�n. Sin embargo, las consecuencias de la producci�n pecuaria para el medio ambiente var�an mucho, en funci�n de las oportunidades y los obst�culos que encuentren los distintos sistemas de producci�n y marcos institucionales y normativos. En el presente art�culo, que se concentra sobre todo en los sistemas de pastoreo extensivo y los sistemas integrados de cultivos-ganado, se examina el hecho menos documentado de que tambi�n puede haber factores externos positivos para el medio ambiente vinculados a la producci�n pecuaria. La producci�n ganadera puede desempe�ar una funci�n importante, por ejemplo, en el apoyo a la ordenaci�n sostenible de los pastizales, la protecci�n de la fauna y flora silvestres y otras formas de biodiversidad, y el aumento de la fertilidad del suelo y el ciclo de los nutrientes, y puede promover de manera directa el valor recreativo de determinados paisajes para otros usuarios. En un art�culo que aparecer� en el pr�ximo n�mero de esta revista se examina la manera de potenciar, mediante instrumentos normativos, la distribuci�n de los beneficios del medio ambiente entre sus m�ltiples usuarios, incluidos los productores pecuarios.

More than half of the world's land surface is used for livestock production, encompassing landscapes of extraordinary natural beauty and of global importance to the biosphere.
The environmental consequences of livestock production vary widely, depending on the opportunities and constraints afforded by different production systems and institutional and policy contexts. But it is now increasingly recognized that such environments are characterized by multiple uses and users, all with legitimate claims on goods and services derived from the environment. These claims cannot be compatible with one another at all times, and relationships among competing claimants can become highly conflictual. The notion of "benefit sharing" refers here to the fact that goods and services derived from the environment provide benefits to a wide range of potential users, among them livestock producers, which need to be balanced. However, since balancing contested claims is inherently a political act, the "appropriate" distribution of environmental benefits among users cannot be defined objectively. As will be argued in the forthcoming article on this subject (Mearns, in preparation), the task of policy analysts must be to expose these multiple contested claims on environmental goods and services; make explicit the choices involved in the design of instruments and mechanisms for benefit sharing; and find those that offer most promise of "win-win" or at least "win-no regret" solutions.

MARKET FAILURE IN DISTRIBUTION OF ENVIRONMENTAL BENEFITS

It is commonly understood that the prices paid for livestock products worldwide fail to reflect fully the environmental costs associated with their production. Government subsidies of various kinds, whether for animal feed, land clearance or for fossil fuel energy used in industrial livestock rearing, together with tariff barriers to trade in livestock products, further distort market prices and exacerbate the environmental costs of livestock produced under certain conditions. The consequences are popularly perceived in the following way:

Rings of barren earth spread out from wells on the grasslands of Turkmenia. Heather and lilies wilt in the nature preserves of the southern Netherlands. Forests teeming with rare forms of plant and animal life explode in flame in Costa Rica. Water tables fall and fossil fuels are wasted in the United States. Each of these cases of environmental decline issues from a single source: the global livestock industry.

Durning and Brough, 1991

There is, of course, a good deal of truth in this perception, which turns on the operative word in the quotation above: the global livestock industry (emphasis added). It is less widely appreciated, however, that there are also positive environmental externalities associated with livestock production - not all of which take place within industrial systems - which are equally unaccounted for in market prices for livestock products. In a wide range of livestock production systems, from extensive grazing to integrated crop-livestock systems, livestock production confers certain environmental benefits which are not well captured by market mechanisms. In some cases, the underlying causal processes are not well understood by policy-makers and, as a result, livestock producers are wrongly castigated for environmental problems that could be avoided with more appropriate institutional, pricing and policy arrangements. It is the purpose of this paper to elaborate on some of the positive environmental externalities associated with livestock production. The article in the next issue (Mearns, in preparation) will suggest ways in which these benefits may be enhanced by policy instruments and shared with other claimants on environmental goods and services.¹ A narrow view of the economy considers only the direct, marketed flows of goods and services from economic production to consumption, and the return flow of labour to economic production. It ignores the underlying natural resource stocks and flows and ecological functions that sustain economic production and human well-being. While livestock production generates direct outputs such as meat, milk, skins and hides, fuel energy and draught power, in this wider view it also entails many positive externalities, including landscape, environmental and species amenity values, waste assimilation and ecological functions such as nutrient cycling and the maintenance of certain conditionally renewable resource stocks. Figure 1 illustrates this broader view of the positive contributions livestock can make to the environment. Placing values on these positive environmental externalities allows for a sounder analysis of the economic benefits, as well as the costs, of livestock production:

Total economic value = direct use value (e.g. livestock products, landscape amenity)

                                    + ecological function value (e.g.  nutrient   cycling,   favouring  seed germination)

                                    + option value (e.g. animal genetic diversity)

                                    + existence value (e.g. satisfaction that domesticated herbivores are there)

Efficient and sustainable resource pricing follows both the "polluter (user) pays" principle and the "beneficiary compensates" principle (Young, 1992). The latter recognizes that livestock production can provide positive environmental benefits and even increase future options, including actions that improve or maintain landscape and biodiversity values and provide environmental services. On this principle, if livestock producers perform additional actions (including forgoing production) to help to maintain highly valued landscapes as diverse as alpine meadows, the Hell's Canyon in Oregon and African savannahs, they should be compensated by the recreational beneficiaries for the ongoing costs of landscape maintenance. (See Krutilla and Cicchetti [1972] for an early study evaluating the benefits of recreational uses of the Hell's Canyon, at a time when the major perceived threat to landscape amenity and biodiversity was the proposed development of hydroelectric power generation rather than livestock production, which is perceived by the environmental lobby as the major threat today.)
For example, the opportunity cost of wildlife conservation in protected areas of Kenya, measured in terms of forgone livestock and agricultural production, has been estimated to be around $203 million per year, or 2.8 percent of total GDP, while revenues from wildlife tourism and forestry contribute only around $42 million per year to the national economy (Norton-Griffiths and Southey, 1995). The authors argue that, given the global nature of the benefits of Kenya's conservation efforts, it is quite inappropriate that so much of the cost is borne by Kenya alone. It will be argued below that wildlife conservation and livestock production are potentially more complementary than this case suggests, but the point remains that the amenity and option values of biodiversity should be fully reflected in the prices paid by those who make use of these benefits and should be used to compensate those who bear the additional costs of providing them.

Resource stocks, flows and the economy
Les ressources, les flux et l'�conomie
Reservas de recursos, sus corrientes y econom�a

Stall-fed cattle in Kakamega district, western Kenya, contribute to on-farm nutrient cycling within an integrated agrisilvipastoral system on a farm of just 0.14 ha
Dans le district de Kakamega, dans l'ouest du Kenya, le b�tail aliment� � l'�table dans le cadre d'un syst�me agrosylvopastoral int�gr�, contribue au cycle des substances nutritives dans une ferme de 0,14 ha seulement
Los vacunos alimentados en el establo en el distrito de Kakamega, Kenya occidental, contribuyen al ciclo de nutrientes en la explotaci�n dentro de un sistema agrosilvopastoral integrado en una finca de apenas 0,14 ha
Photo/Foto: R. Mearns
 

TYPES AND OVERALL SIGNIFICANCE OF LIVESTOCK PRODUCTION SYSTEMS

Extensive grazing systems are based almost exclusively on livestock kept on rangelands (i.e. unimproved grasslands, shrublands, savannahs, deserts and tundra), with no or only limited integration with crops and little reliance on imported inputs (Steinfeld, de Haan and Blackburn, 1996). Of all livestock production systems, extensive grazing systems are the most likely to coincide geographically with areas of high value for wildlife and other forms of biodiversity. Rangelands occupy 51 percent of the earth's land surface (almost 90 percent of agricultural land in Africa, West and Central Asia and Latin America, and more than 60 percent of agricultural land elsewhere in Asia), contain about 36 percent of its total carbon in living and dead biomass, include a large number of economically important species and ecotypes, support 50 percent of the world's livestock² and are the livelihood of millions of people (25 million in Africa alone) who would otherwise have to make a living outside the rangelands at an arguably greater net cost to the environment
Extensive grazing systems are usually geared to the production of multiple outputs, including meat, milk, blood, hides and skins, dung fuel, transportation, flexible household capital reserves and risk management, although ranching systems are generally geared more narrowly towards meat production. Many of these outputs are untraded and markets fail to capture even their direct use values, let alone the broader environmental benefits. Scoones (1995) summarizes the findings of a number of studies comparing returns to ranching (single output systems) and pastoral production (multiple outputs) in Africa, showing that pastoral production consistently outperforms ranching on a per hectare basis. While pure grazing systems may produce only 9 percent of world meat and 8 percent of world milk production (Steinfeld, de Haan and Blackburn, 1996), their value in providing multiple direct outputs and additional indirect benefits, such as the preservation of landscape amenity and wildlife biodiversity, justifies continued efforts to specify accurately the nature of livestock-environment interactions within them.

Crop-livestock integration is the main avenue for intensification in more humid and subhumid regions, where external inputs are not available, and it can support higher rural populations than extensive grazing systems alone. Integrated crop-livestock systems can be environmentally beneficial, since by-products from one production component (e.g. crop residues, manure) serve as inputs to other components. Livestock play a key role in energy and nutrient cycling as well as providing a diverse range of outputs (McDowell, 1977), and the rotation of crops with forage legumes replenishes soil nutrients and reduces soil erosion. Even considering direct use values alone, the estimated contribution of livestock to agricultural GDP in Africa, including manure and draught power, may be as high as 35 percent (Winrock International, 1992).
Crop-livestock integration may take place at a range of scales, from a single farm unit to an entire region. "Mixed farming" usually refers to integration within a single farm unit (Winrock International, 1992), but it is useful to consider farmer-herder interactions on an intraregional scale under the same general heading, since such interactions have certain advantages over mixed farming, especially in relation to equity and the efficient use of skilled labour (Bayer and Waters-Bayer, 1995). While integrated crop-livestock production is the most prevalent livestock production system in much of Asia, in Africa it has usually occurred as a process of factor and input substitution which has largely been induced by population growth (McIntire, Bourzat and Pingali, 1992; Tiffen, Mortimer and Gichuki, 1994).

Industrial systems. Further intensification generally implies the import of external inputs which can bring to an end the beneficial equilibrium between livestock and the environment. Manure, for example, while of primary importance in integrated crop-livestock systems, can become a harmful pathogen when present in excessive quantities. Industrial systems tend to be geared towards the production of single rather than multiple outputs and towards outputs that are usually traded on markets. The fastest growing sector of the global livestock industry is poultry production, which increased by 48 percent between 1984 and 1994, compared with a 3 to 6 percent increase for the principal ruminant animals (see Table)
The principal focus of this paper is on extensive grazing and integrated crop-livestock systems, since it is in these systems that benefit-sharing between livestock production and other claimants on the environment is most prevalent and offers most potential for enhancement through policy intervention. Rather than attempt a comprehensive overview, the discussion highlights those issues which seem to be most frequently misrepresented and which offer substantial scope for benefit-sharing through innovative institutional and policy initiatives. In industrial systems the relevant policy options are more a question of limiting damage or reducing the environmental costs associated with livestock production (Young, 1996), issues that fall outside the scope of the present discussion.

World livestock totals and species diversity
Recensement mondial du b�tail et diversit� des esp�ces
Total mundial de cabezas de ganado y diversidad de especies

Sources: For livestock production totals, FAO (1994); for information on species diversity, World Conservation Monitoring Centre (1994).

ENVIRONMENTAL GOODS AND SERVICES APPROPRIATE FOR BENEFIT SHARING

This section reviews the main types of environmental goods and services appropriate for benefit sharing. First we consider those environmental services provided by livestock production that have ecological function values, including the maintenance of terrestrial ecosystems (supporting rangeland productivity, nutrient cycling and soil fertility enhancement as well as carbon sequestration), and the preservation of wildlife and other forms of biodiversity. Next are those environmental goods and services that yield direct use values to society, and which livestock production helps to provide. These include landscape amenity, weeding services, draught animal power and livestock-derived energy sources. In the case of draught power and household energy supply from livestock, additional environmental benefits derive from the fact that they carry lower opportunity costs in terms of net greenhouse gas emissions, compared with alternative (fossil-fuel based) means of supplying the same services. Finally, we consider livestock-related environmental goods that have option values, especially animal genetic resources.

ECOLOGICAL FUNCTION VALUES

Sustainable rangeland management. Conventional wisdom suggests that much of the blame for "desertification" and land degradation in arid rangelands rests with pastoral livestock production. There is now a considerable literature which corrects this misconception on two counts: the extent of dryland degradation is greatly exaggerated because the underlying ecological dynamics have been misunderstood³ (Behnke, Scoones and Kerven, 1993; Swift, 1996); and the contributory role of livestock has also been misspecified (Sandford, 1983; Homewood and Rodgers, 1987; Behnke, 1994). If desertification is understood as irreversible degradation, then a far smaller proportion of arid rangelands is thus affected. Dryland ecosystems are now understood to be:

• highly variable over time, heterogeneous in space and resilient;
• areas in which long-term primary productivity is influenced more by abiotic factors such as rainfall than by the density of grazing livestock within the system;
• areas in which the flexibility of opportunistic or "tracking" strategies of mobile animals, along with many other adaptations herders and farmers make to the vagaries of such dynamic, event-driven ecosystems, allows the exploitation of the varied phenology, production dynamics and forage quality of diverse feed sources.

Goats have been found to play a key role in successfully establishing the important Acacia tortilis tree in Turkana, northern Kenya
Les caprins jouent un r�le fondamental dans l'implantation de l'Acacia tortilis � Turkana, dans le nord du Kenya
Se ha comprobado que las cabras desempe�an una funci�n decisiva en el establecimiento del importante �rbol Acacia tortilis en Turkana, Kenya septentrional
Photo/Foto: R. Mearns

Encroachment on village commons such as this one in Rajasthan, India, is threatening the sustainability of integrated crop-livestock production
L'empi�tement sur les terres communales, comme dans ce village du Rajasthan, Inde, repr�sente une menace pour la durabilit� d'une production agriculture-�levage int�gr�e
La invasi�n de terrenos comunales de aldeas como �sta de Rajasthan, India, representa una amenaza para la sostenibilidad de la producci�n integrada cultivos-ganado
Photo/Foto: R. Mearns

These factors make it possible for continued human habitation of "marginal", variable dryland environments such as the Sahel. They also permit the integration of several production systems on a regional basis, each of which would be unviable on its own, as in the case of the Inland Niger Delta (Moorehead, 1991). Therefore, under the right conditions, production systems relying on mobile livestock represent the most sustainable way to utilize arid rangelands (Box 1), and ought to be supported and enhanced through policy intervention designed to give greater decision-making power to local producer groups (Scoones, 1995; Swift, 1995). These issues are addressed in the article to appear in the next issue (Mearns, in preparation)
A wealth of evidence exists to support the view that light or moderate grazing by livestock increases rangeland productivity in many grazing systems. For example, the removal of coarse dead stems permits succulent new shoots in species such as Themeda triandra in African savannahs. The seeds of some plant species are spread efficiently by being carried in cattle guts and then deposited in dung in favourable seed beds or trampled into the soil. The passage of herbage through the gut and its expulsion as faeces modifies the nitrogen cycle so that grazed pastures tend to be richer in nitrogen than ungrazed ones. The recruitment of tree species is also favoured under certain conditions by grazing animals. Reid and Ellis (1995) found that goats play a key role in enhancing recruitment reliability of the important Acacia tortilis tree in South Turkana, Kenya. Similarly, in nature reserves along South Africa's Eastern Cape, the establishment of certain rare tree and shrub species, including cycad and the endemic Pondoland palm which are regarded as an important justification for nature conservation in the area, appears to be favoured in former homestead sites where livestock corrals have concentrated nutrients (Thembela Kepe, personal communication, 1996). Goats have been found to play an important role in the maintenance of Arizona chaparral by reducing brush cover (Severson and Debano, 1991) and in controlling the noxious weed leafy spurge throughout the western United States, thereby enhancing biodiversity and landscape amenity. Indeed, the removal of grazing pressure owing to the forced abandonment of grazing land in areas of endemic armed conflict, such as the Turkana district of Kenya and the areas which border it, can itself lead to undesirable landscape changes in the form of dense thorny scrub invasion (Conant, 1982; Hendrickson, Mearns and Armon, 1996). The potential complementarities between landscape amenity, wildlife biodiversity and grazing livestock production are discussed separately below.

Preservation of wildlife biodiversity. The relationships between wild and domestic ungulates coexisting in the same habitats are complex and are determined by the extent of dietary overlap and competition for forage, as well as by disease vectors. For example, domestic sheep are acknowledged to be carriers of diseases that threaten populations of wild Bighorn sheep in the western United States. These relationships are by no means always competitive, however. Many recent studies point to the potential for complementarity and even symbiosis between wild and domestic ungulates, especially in relation to foraging patterns. Domestic as well as wild ungulates are an integral component of co-evolved dryland ecosystems in many regions of the world (to cite but a few studies: Homewood and Rodgers, 1987 and Little, 1996, for East Africa; Hoffman, in press, for South Africa; Perevolotsky, 1995, for the Negev, Israel; Sheehy, 1995, for Mongolia and China; and West, 1993; Sheehy and Vavra, 1996 and Hobbs et al., 1996, for the western United States). Failure to recognize these potential complementarities has led to missed policy opportunities for achieving benefit sharing between livestock and the environment (Box 2). The presumption that livestock are necessarily inimical to the conservation of wildlife biodiversity has led to policies favouring wildlife over pastoralists, with consequences that perversely harm the environment as well as livestock producers and national economies (McCabe, Perkin and Schofield, 1992; Norton-Griffiths and Southey, 1995).

The state of science in biodiversity conservation is now shifting from the protection of "charismatic" species to the defensive management of larger tracts of land with habitats or ecosystems holding suites of sensitive species (West, 1993; Perrings, 1995). It is increasingly acknowledged that moderate livestock grazing will actually increase the chances of survival of some species and can enhance community- and landscape-level diversity in many instances (West, 1993).

Soil fertility enhancement/nutrient cycling. In integrated crop-livestock systems, benefits are shared between livestock production and other uses of the environment in terms of soil fertility enhancement and nutrient cycling, whether on-farm, intravillage, or intraregion (Bayer and Waters-Bayer, 1995). Pastures and fodder fields suffer less soil erosion and absorb more water than row crop fields, and leguminous fodder plants such as alfalfa also improve soil fertility. Manure from livestock (pigs and ruminants together) may contribute as much as 35 percent of soil organic matter (Steinfeld, de Haan and Blackburn, 1996) while also helping to maintain soil structure, water retention and drainage capacity. The value of manure is so well recognized that many farmers keep livestock primarily for this purpose. Feeding crop residues to livestock is also the best way to utilize "waste" products, as nutrient uptake is achieved more efficiently than when stalks are added directly to the soil, while burning increases CO₂ emissions.
With growing population densities, farmers in semi-arid areas such as the Sahelian and Sudanian belts of West Africa face rising transaction costs in obtaining manure (Toulmin, 1992). This raises the question, why not move to mixed farming rather than relying on feed-manure exchanges between farmers and herders and thereby internalize those transaction costs? Bayer and Waters-Bayer (1995) suggest that one reason why farmer-herder exchanges persist is that they allow greater efficiency in the use of skilled labour. This finding is supported by Delgado (1978) on the grounds of the high opportunity cost of seasonal labour in farming.
While crop-livestock interaction can at best maintain nutrient balances, positive trends are also possible, including shifting from cattle to sheep and goats and introducing stall feeding, which significantly increases the amount of nutrients available from manure (Box 3). The cultivation of legume fodders and trees, for example in alley farming systems, also contributes to soil enrichment through nitrogen fixation. In Colombia and Viet Nam, where sugar cane is used as livestock feed, it has been shown that the recycling of dead leaves into the soil, instead of burning them, favours nitrogen fixation by bacteria and reduces weed growth, thus increasing crop yields (Sansoucy, 1995).

Carbon sequestration. It is very difficult to make generalizations about the role of livestock production systems in contributing to global warming via carbon emissions. While livestock grazing is responsible for removing herbaceous and woody biomass, an inverse relationship is also commonly observed between the extent and frequency of fires and livestock density. That is, greater livestock density reduces biomass removal by fires, thereby increasing available herbage and reducing relative removal rates by livestock (de Leeuw and Reid, 1995). For all of Africa in 1993, land use change resulted in an estimated 730 million tonnes of CO₂ emissions, of which only 9 million tonnes net, or just over 1 percent, were contributed by livestock production (World Bank, 1996).
Although the relationships are complex and difficult to generalize, many microstudies, such as one carried out in the Netherlands (Vandasselaar and Lantinga, 1995), show higher soil carbon fixation under livestock grazing by comparison with other management regimes. The terrestrial stock of carbon, however, is highly uncertain, and has been hypothesized as a possible site for a "missing" carbon sink in which the maintenance of savannah ecosystems may play an especially important role. What is known, however, is that various technological options exist for inducing incentive-compatible forms of land-use change under livestock production as ways to achieve higher standing biomass cover and therefore net carbon storage. These options include efforts to slow rates of land clearance for agriculture and to increase production of perennial fodder crops and trees in farming systems (Leach and Mearns, 1988; Swallow, 1995).

DIRECT USE VALUES

Landscape amenity. Many of the world's highly valued grassland landscapes, e.g. the North American prairies, the Argentinian pampas, the East African savannahs, the Mongolian steppes and various alpine meadows, have long been grazed by domesticated as well as wild herbi-vores. Cattle, sheep, goats and other ungulates appear to have been first domesticated around 9 000 to 11 000 years ago, and 6 000 to 8 000 years ago people began taking herds on to savannah landscapes in Africa (Lamprey, 1983, cited in Young and Solbrig, 1992). These are co-evolved landscapes, and grazing livestock play an integral role in their maintenance (West, 1993). They are also anthropogenic landscapes (Spooner and Mann, 1982; Adams and McShane, 1992; Leach and Mearns, 1996), and many people place both direct use and option values on their preservation, including human artefacts linked to livestock production such as drystone walls in the British Pennines and traditional hay stooks in the Austrian Tyrol. Within Europe, benefit-sharing mechanisms have been addressed explicitly, and income support payments are made to farmers in the interests of landscape preservation. Payments are made at the European Union level, for example, to compensate farmers in designated Environmentally Sensitive (or Stewardship) Areas for grazing extensification with the aim of restoring vegetation species diversity (Bullock and Kay, 1997). In southern England, public nature trusts, themselves, own flocks of sheep used in the management of chalk downlands, since selective grazing is the only known way to maintain vegetation species richness in these fragile landscapes.

Kazak herders in western Mongolia are among the many who have returned to the use of draught transport for moving between seasonal camps since the breakup of pastoral collectives in the early 1990s
Les gardiens de troupeau Kazak, dans l'ouest de la Mongolie, sont au nombre de ceux qui ont recommenc� � utiliser la traction animale pour leurs d�placements entre les campements saisonniers, depuis le d�membrement des p�turages collectifs au d�but des ann�es 90
Los pastores kazakos de Mongolia occidental son de los muchos que han vuelto al uso del transporte con animales de tiro para desplazarse entre los campamentos estacionales desde la dispersi�n de los colectivos pastorales a comienzos de los a�os noventa
Photo/Foto: R. Mearns

The grazing of domestic livestock in Mongolia's Khangai mountains helps maintain a rich and diverse forage base and complements foraging by wild herbivores
Dans les montagnes du Khanga�, en Mongolie, le pacage du b�tail domestique contribue au maintien d'une base fourrag�re riche et vari�e, et vient s'ajouter � celui de la faune herbivore
El pastoreo del ganado dom�stico en las monta�as Khangai de Mongolia contribuye a mantener una base de forraje rica y diversa y complementa la b�squeda de alimentos de los herb�voros silvestres
Photo/Foto: R. Mearns

Draught animal power. Some 52 percent of the cultivated area in developing countries (excluding China) is farmed by using only draught animals. Compared with the use of tractors, animal power is a renewable energy source, is produced on-farm with almost all of the required implements made locally, has far lower opportunity costs in terms of greenhouse gas emissions from fossil fuel burning and offers additional environmental benefits from nutrient cycling (Sansoucy, 1995; Singh et al., 1995). It has also been argued that animal traction can have positive gender impacts (Hofs, 1993). Unlike in much of Asia, efforts to introduce animal traction in Africa have been disappointing, given the relative opportunity costs to farmers of land, labour and capital (McIntire, Bourzat and Pingali, 1992). Even in many parts of Africa, however, conditions have been right for the adoption of animal traction, including rising population densities and the introduction of high value added cash crops and market accessibility (Delgado, 1989; Tiffen, Mortimer and Gichuki, 1994), and that even the high initial capital investment costs (Panin and de Haen, 1989) can be overcome.

Household energy supply. In many countries, animal dung is a preferred cooking fuel, either year-round, seasonally, or for particular types of cooking. It is the major source of household energy for millions of people in Asia, Africa, parts of the Near East and Latin America. It is often argued that burning dung as fuel carries a very high opportunity cost in terms of "lost" soil nutrients. One study using replacement cost valuation techniques, for example, estimated this opportunity cost to be as much as 9 percent of Ethiopia's GNP in 1983 (Newcombe, 1989, cited in Pearce and Warford, 1993). This is almost certainly a gross exaggeration, based on the fallacy that using dung as fuel is necessarily diversionary. As other studies show, however, the use of dung as fuel is rarely a recent phenomenon, and may have been practised in particular localities over extremely long time periods without any "diversion" of soil nutrients (Leach and Mearns, 1988). Indeed, the case is usually made in order to justify large-scale afforestation projects, which frequently incur heavy costs in terms of lost grazing for livestock.
Biogas production from animal manure has also been successfully adopted by millions of farmers in developing countries as a source of household energy replacing fossil fuel or fuelwood. About 25 million people use it in China alone (Sansoucy, 1995). Effluent from biodigesters can also be recycled as fertilizer (with even better results than the original manure) or as fish feed in aquaculture systems and they can provide additional services such as lighting, warm water, water-pumping and heating. All of these applications substitute energy sources with arguably higher environmental costs in terms of greenhouse gas emissions.

Weeding services. Livestock, especially sheep, are also efficient in controlling weeds, with environmental benefits in terms of landscape amenity value and biodiversity as well as economic benefits in higher crop yields. Sheep weeded American corn fields before the Second World War, for example, and ducks and geese still control weeds on Southeast Asian farms (Baker et al., 1990). Livestock graze beneath trees in rubber and oil-palm plantations in Malaysia, thereby increasing overall production while reducing the cost of weed control (using less environmentally acceptable methods) by up to 40 percent (Sansoucy, 1995). It is common to use livestock grazing as a means to reduce fire hazards in forests by mitigating accidental burning at inappropriate times. Burning management regimes for livestock production are practised in areas as diverse as those of the Mediterranean, British moorlands and South Africa.

OPTION VALUES

Animal genetic resources. The four principal mammalian livestock species (cattle, sheep, goats and pigs) have diversified, after more than 5 000 years of domestication and artificial selection, into more than 2 000 recognized breeds, each with unique characteristics (Table). The intensification of production has gone hand in hand with a narrowing of the genetic base, especially among cattle and pigs. But it is now recognized that the pool of genetic resources represented by domestic animal diversity is an essential basis for global food security and is likely to be of increasing importance in more demanding production environments.
Traditional breeding practices tend to select for survival under conditions of stress such as extreme cold and seasonal feed deficits (see FAO, 1991, for the case of Mongolia), unlike commercial breeding which selects for meat or milk productivity under controlled, high-input conditions. In arid, drought-prone rangelands, low-input animals such as zebu cattle are physiologically adapted to "track" available feed and water supplies by seasonally altering their metabolic rate, thus permitting optimum exploitation of highly variable environments (Western and Finch, 1986; Bayer and Waters-Bayer, 1995). However, attempts to introduce highly productive, exotic breeds into high-stress environments have almost always failed (Sheehy, 1993) in the cases of Mongolia and Inner Mongolia as well as in the case of Bos indica in northern latitudes of North America (the author is grateful to Dennis Sheehy for suggesting this example). Such introductions have also been to the detriment of locally adapted and highly variable animal genetic resources - precisely the qualities required to develop and sustain production further in otherwise inhospitable environments. FAO conservatively suggests that one in four breeds is now threatened with extinction (Hammond and Leitch, 1996).

CONCLUSION

This paper has reviewed the environmental goods and services appropriate for benefit-sharing between livestock production and other legitimate claimants on the environment, including future generations whose preferences cannot yet be known. It is clear that livestock can, under the right conditions, be good for the environment. But not all of these benefits can be maximized at all times for all users. The environment in extensive grazing and crop-livestock production systems is above all characterized by multiple uses and users. This poses significant analytical challenges, but advances have been made recently in the understanding of how to account for benefit-sharing and how to translate analytical insights into policy recommendations. These issues are taken up in the second part of this article, to appear in the next issue of World Animal Review (Mearns, in preparation).

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¹ For the purposes of this article, we adopt the following working definitions. "Environmental goods" refer to the specific source (material and energy natural resource) inputs that are essential to sustaining the livelihoods of present and future generations of people. "Environmental services" refer to sink (pollution-absorbing, nutrient cycling) and other service functions of the environment (e.g. the hydrological cycle) that are also essential to sustaining the livelihoods of present and future generations of people. Other direct use values, such as the amenity value of particular landscapes, may also be a highly important source of well-being; it is arguable whether these should be defined as environmental goods or services. Environmental goods are "resources" in the sense that they are "materials available `in nature' that are capable of being transformed into things of utility to man [sic]" (Harvey, 1979). As Harvey makes clear, resources can only be defined in relational terms, and they are a function of the knowledge and technology within a given cultural context.
²  II World IPCC Working Group Wide Web Home Page: http://www.usgcrp.gov/ipcc/html/chap02.html.
³The science of dryland degradation has in fact been well understood for several decades, for instance the fact that large interannual shifts in desert margins and biomass production can be explained by variations in rainfall. Swift (1996) argues that the persistence of the "desertification" concept despite mounting evidence that it is inaccurate, and the perpetuation of policies based on the view that pastoral livestock production is largely to blame have less to do with science than with the competing claims of different political and bureaucratic constituencies.