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Environmental Services Ofbiodiversity Proc. Natl. Acad. Sci. USA Vol. 93, pp. 2764-2769, April 1996 Ecology Environmental services of biodiversity NORMAN MYERS Green College, Oxford University, United Kingdom OX3 8SZ Contributed by Norman Myers, September 29, 1995 ABSTRACT Humans derive many utilitarian benefits and they occur in every last segment of the biosphere. So the from the environmental services of biotas and ecosystems. paper is perforce restricted to an illustrative selection of the This is often advanced as a prime argument to support more significant services. conservation of biodiversity. There is much to be said for this viewpoint, as is documented in this paper through a summary II. Conceptual Background assessment of several categories of environmental services, including regulation of climate and biogeochemical cycles, Biodiversity embraces the totality of life forms, from the hydrological functions, soil protection, crop pollination, pest planetary spectrum of species to subunits of species (races, control, recreation and ecotourism, and a number of miscel- populations) together with ecosystems and their ecological laneous services. It is shown that the services are indeed processes. The species component includes all plants, animals, significant, whether in ecological or economic senses. Partic- and microorganisms, of which there are between 8 million and ularly important is the factor of ecosystem resilience, which 30 million (conceivably 100 million) (12). The subspecies appears to underpin many of the services. It should not be component includes populations, ofwhich there could be many supposed, however, that environmental services stem necessarily billions (13). Spanning both these main categories are various and exclusively from biodiversity. While biodiversity often plays subdivisions, including community diversity, food web diver- a key role, the services can also derive from biomass and other sity, keystone diversity, and functional diversity. attributes of biotas. The paper concludes with a brief overview Environmental services are also known as ecosystem ser- assessment of economic values at issue and an appraisal of the vices,* both terms reflecting environmental functions and implications for conservation planning. ecological processes. They can be defined as any functional attribute of natural ecosystems that are demonstrably benefi- I. Introduction cial to humankind (15). Theycomprise the main indirect values of biodiversity, as opposed to direct values in the form of Conservation biologists increasingly face the question, What is material goods such as timber, fish, plant-based pharmaceu- biodiversity good for? Naive as this may seem to some, it is a ticals, and germ-plasm infusions for major crops. They include valid question. There is no longer enough room for a complete generating and maintaining soils, converting solar energy into stock of biodiversity on an overcrowded planet with almost six plant tissue, sustaining hydrological cycles, storing and cycling billion humans and their multifarious activities, let alone a essential nutrients (notably in the form of nitrogen fixation), projected doubling of human numbers and a tripling or supplying clean air and water, absorbing and detoxifying quadrupling of salient activities. So biodiversity must stake its pollutants, decomposing wastes, pollinating crops and other claims for living space in competition with other causes. plants, controlling pests, running biogeochemical cycles (of Generally speaking, biodiversity must urge the merits of its such vital elements as carbon, nitrogen, phosphorus, and cause through what it contributes to human welfare, preferably sulfur), controlling the gaseous mixture of the atmosphere doing it in the way that most appeals to political leaders and (which helps to determine climate), and regulating weather the general public, namely in economic terms. and climate at both macro and micro levels. Thus they basically In response to the question above, conservation biologists include three forms of processing, namely of minerals, energy, proclaim the many significant contributions of biodiversity to and water (16). In addition, biodiversity provides sites for the human cause. There are two categories of contributions: research, recreation, tourism, and inspiration (1, 17, 18). material goods and environmental services. The first has been The bulk of this paper will be given over to describing and frequently and widely documented (1-4), principally in the evaluating certain of these services. But first, a couple of form of new and improved foods, medicines and drugs, raw caveats. It is far from true that all forms of biodiversity can materials for industry, and sources of bioenergy. The second contribute all environmental services or that similar forms of has been far less documented even though the issue was biodiversity can perform similar tasks with similar efficiency. identified as unusually significant almost two decades ago (5) How far do environmental services depend upon biodiversity and even though its total value is surely far greater than that per se? Recent research suggests that they are highly resilient of the first (1, 6-9). The main reasons for this lamentable to some loss of species and they can keep on supplying their lacuna are that scientists find it much harder to demonstrate services even in highly modified states. A sugarcane plantation the precise nature of the services, and it is still harder to may be more efficient at producing organic material than the quantify them economically. Whereas the benefits of material natural vegetation it replaced, and a tree farm may be more goods tend to accrue to individuals, often as producers or capable of fixing atmospheric carbon than a natural forest. At consumers in the marketplace, the values of environmental the same time, many natural ecosystems with low biodiversity services generally pertain to society, and hence they mostly (e.g., tropical freshwater swamps) have a high capacity to fix remain unmarketed (10, 11). carbon. This paper reviews our knowledge and understanding of the principal services at issue. The services are extremely diverse, *The term environmental services is preferred since it embraces the larger-scale and often more important services, such as the albedo The publication costs of this article were defrayed in part by page charge stabilization supplied by the Amazonia and Zaire forests (14). These payment. This article must therefore be hereby marked "advertisement" in forest regions are too large to conform to the category of ecosystems accordance with 18 U.S.C. §1734 solely to indicate this fact. as conventionally understood. Downloaded by guest on September 28, 2021 2764 Ecology: Myers Proc. Natl. Acad. Sci. USA 93 (1996) 2765 Similarly, the services supplied by one form of biodiversity and parts of the Philippines among other areas-rainfall in one locality may not necessarily be supplied by a similar form regimes have been disrupted if not depleted in the wake of of biodiversity in another locality. Just because a wetland on deforestation (28). the Louisiana coast performs a particular suite of functions, it 2. Biogeochemical Cycles. The Earth's biotas are prime cannot be assumed that a wetland on the Georgia coast will pumps in the major biogeochemical cycles (29-31). It is perform the same functions, still less an inland wetland in debatable, however, how far this function is impaired by loss Massachusetts or California, and still less again a montane of biodiversity in itself, rather than by loss of vegetation and wetland in Sweden or a forest wetland in Thailand. Services other biomass (32, 33). tend to be quite site-specific. This makes it much more difficult A notable illustration lies with the carbon cycle and, hence, for conservation biologists to demonstrate the intrinsic value with climate change in the form of global warming. Roughly of wetlands or any other biotopes. half of global warming is due to build-up of anthropogenic Biodiversity plays two critical roles. (i) It provides the carbon dioxide in the global atmosphere. More carbon dioxide biospheric medium for energy and material flows, which in is released than remains in the atmosphere, the rest being turn provide ecosystems with their functional properties; and absorbed by the oceans and terrestrial biotas. (ii) it supports and fosters ecosystem resilience (17, 19-24). As While vegetation can serve as a major sink of carbon biodiversity is depleted, there is usually a shift and often dioxide, we do not know how much, nor how far, the function (though not always) a decline in the integrity of ecosystem depends on biodiversity. Preliminary evidence shows that processes that supply environmental services. species-rich ecosystems can often (though not always) con- The second caveat is that we should distinguish between sume carbon dioxide at a faster rate than less diverse ecosys- what can be called the ecologist's and the economist's mode of tems; and in turn this suggests that biodiversity decline may calculation of values at issue. The first favors estimating promote the build-up of carbon dioxide (34). In addition, to biodiversity's values "in themselves," i.e., the worth of a the extent that species-rich ecosystems produce more biomass, biodiversity attribute as manifested by its role in ecosystem they consume more carbon dioxide, thereby reducing the workings (for example, the part played by forest cover in build-up of carbon dioxide. watershed functions). The second approach prefers
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