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3 The Values of Biodiversity The individual components of biodiversity—genes, species, and ecosystems—provide society with a wide array of goods and services. Genes, species, and ecosystems of direct, indirect, or potential use to humanity are often referred to as "biological resources" (McNeely and others 1990; Reid and Miller 1989; Wood 1997). Examples that we use directly include the genes that plant breeders use to develop new crop varieties; the species that we use for various foods, medicines, and industrial products; and the ecosystems that provide services, such as water purification and flood control. The components of biodiversity are interconnected. For example, genetic diversity provides the basis of continuing adaptation to changing conditions, and continued crop productivity rests on the diversity in crop species and on the variety of soil invertebrates and microorganisms that maintain soil fertility. Similarly, a change in the composition and abundance of the species that make up an ecosystem can alter the services that can be obtained from the system. In this chapter, we review the types of goods and services that mankind obtains directly and indirectly from biodiversity and its components. Biodiversity contributes to our knowledge in ways that are both informative and transformative. Knowledge about the components of biodiversity is valuable in stimulating technological innovation and in learning about human biology and ecology. Experiencing and increasing our knowledge about biodiversity transform our values and beliefs. There is a fairly large literature characterizing nonextractive ecosystem services with direct benefit to society, such as water pollution and purification, flood control, pollination, and pest control. In addition, such services in biophysical and economic terms characterize the institutional mechanisms needed to generate incentives for their preservation (Daily
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1997; Missouri Botanical Garden forthcoming). In this chapter, we review the types of social and cultural values associated with knowledge of biodiversity. We use those values in chapter 4 to discuss how they can contribute to decisions on management of biodiversity. Biological Values The components of biodiversity are the source of all our food and many of our medicines, fibers, fuels, and industrial products. The direct uses of the components of biodiversity contribute substantially to the economy. In 1989, US agriculture, forestry, and fisheries contributed $113 billion1 to the US gross domestic product (GDP), equal to the contribution of the chemical and petroleum industries combined (DOC 1993). The full contribution of biodiversity-related industries to the economy is higher still, in that it includes shares of such sectors as recreation (see Everglades and Boulder, Colo., case studies in this chapter and Lake Washington case study in chapter 6), hunting (see Quabbin Reservoir case study in chapter 6), tourism (see Costa Rica case study in chapter 2), and pharmaceuticals. The economies of most developing countries depend more heavily on natural resources, so biodiversity-related sectors contribute larger shares of their GDPs. For example, the sum of the agriculture, forestry, and forest-industry products in Costa Rica in 1987 accounted for 19% of the nation's GDP (TSC/WRI 1991), whereas these sectors accounted for only 2% of the US GDP (DOC 1993). The relatively small direct economic contribution of biological resources in the two countries illustrates the difficulty of "valuing" biodiversity. The small fraction of the value of these ecological systems that is accounted for in US economic ledgers contrasts starkly with the fact that our survival depends on functioning ecological systems. At the same time, our limited ability to value ecological parallels our limited appreciation of our dependence on these systems. The imperfections of our knowledge are seen in the $200 million Biosphere 2 trial—in the unsuccessful attempt to house eight people for 2 years in an ecologically closed system. Cohen and Tilman (1996) concluded that "no one yet knows how to engineer systems that provide humans with the life-supporting services that natural ecosystems produce for free." Biodiversity in Domesticated Systems Humans rely on a relatively small fraction of species diversity for food. Only about 150 species of plants have entered world commerce, and 103 species 1 This measure and measures that follow in the chapter are very general indications of monetary values associated with various aspects of biodiversity. They are calculated in different ways and have different bases for calculation. Care should be taken in comparison.
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account for 90% of the supply of food plants by weight, calories, protein, and fat for most of the world's countries (Prescott-Allen and Prescott-Allen 1990). Just three crops—wheat, rice, and maize—account for roughly 60% of the calories and 56% of the protein consumed directly from plants (Wilkes 1985). Relatively few species that have not already been used as foods are likely to enter our food supply, but many species now consumed only locally are likely to be introduced into larger markets and grown in different regions. For example, the kiwi fruit was introduced into the United States as recently as 1961; within 20 years, US sales had grown to some $22 million per year (Myers 1997). Although relatively few species are consumed for food, their productivity in both traditional and modern agricultural systems depends on genetic diversity within the species and interactions with other species found in the agroecosystem. Claims that such biodiversity "archives" can serve as substitutes for biodiversity in natural habitats are more fanciful than factual. Genetic diversity provides the raw material for plant breeding, which is responsible for much of the increases in productivity in modern agricultural systems. In the United States from 1930 to 1980, plant breeders' use of genetic diversity accounted for at least the doubling in yields of rice, barley, soybeans, wheat, cotton, and sugarcane; a threefold increase in tomato yields; and a fourfold increase in yields of maize, sorghum, and potato. An estimated $1 billion has been added to the value of US agricultural output each year by this widened genetic base (OTA 1987). Breeders rely on access to a wide range of traditional cultivars and wild relatives of crops as sources of genetic material that is used to enhance productivity or quality. Different landraces can contain genes that confer resistance to specific diseases or pests, make crops more responsive to inputs such as water or fertilizers, or confer hardiness enabling the crop to be grown in more extreme weather or soil conditions. Much of the genetic diversity available for crop breeding is now stored in a network of national and international genebanks administered by the UN Food and Agriculture Organization, the Consultative Group on International Agricultural Research, and various national agricultural research programs, such as the US Department of Agriculture's National Seed Storage Laboratory in Fort Collins, Colorado. The value of these genebanks for agricultural improvement is substantial. For example, in a presentation to this committee,2 Evenson and Gollin estimated the present net value of adding 1,000 cataloged accessions of rice landraces to the International Rice Research Institute's genebank at $325 million (on the basis of empirical estimates that these accessions would generate 5.8 additional new varieties, which would generate an annual $145 million income stream with a delay of 10 years). As important as they are in agriculture, 2 Presentation to the full committee at its October 1995 workshop, "Issues in the Valuation of Biodiversity," by Robert Evenson, Yale University.
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genebanks, and other in situ collections (cyropreserved and in zoos) are viable only for a very narrow array of species. The important contribution of genebanks to agricultural productivity has been recognized by government since the 18th century. It led to the rise of botanical gardens and expeditions in search of new plant varieties, including the fabled voyage of the HMS Bounty (Fowler 1994), and is growing substantially as traditional landraces continue to be replaced by modern varieties. Genetic engineering has greatly increased the supply of genetic material available for introduction into crop varieties. Genes from any species of plant, animal, or microorganism can now be moved into a particular plant. For example, genes from the winter flounder have been transferred into the tobacco genome to increase its frost resistance, and genes from the microorganism Bacillus thuringiensis have been transferred into corn, wheat, and rice to give them resistance to insect pests. Genetic engineering is not without considerable risks, and its ultimate success will depend on genetic variability in natural populations. It is clear that the rapid increase in uses of genetic engineering will continue as knowledge and applications of new techniques increase. Not only are specific genes valuable in modern agricultural systems, but the maintenance of genetic diversity is also valuable in traditional agricultural systems. The greater the genetic uniformity of a crop, the greater the risk of catastrophic losses to disease or unusual weather. In 1970, for example, the US corn harvest was reduced by 15%—for a net economic cost of $1 billion—when a leaf fungus spread quickly through a relatively uniform crop (Tatum 1971). Since then, breeders have taken greater precautions to ensure that a heterogeneous array of genetic strains are present in fields, but problems due to reduced diversity still recur. The loss of a large portion of the Soviet Union's wheat crop to cold weather in 1972 and the citrus canker outbreak in Florida in 1984 both stemmed from reductions in genetic diversity (Reid and Miller 1989). Humans also use a relatively small number of livestock species for food and transportation: only about 50 species have been domesticated. Here, too, genetic diversity is the raw material for maintaining and increasing the productivity of species. Biodiversity in Wild Systems Humans still harvest considerable quantities of food, fuel, and fiber from nondomesticated ecosystems. For example, gross revenue from the world marine fisheries in 1989 amounted to $69 billion (WRI 1994). Fish contribute only 5% of the protein consumed worldwide, but the proportion can be much higher locally. In Japan, the Philippines, the Seychelles, and Ghana, for example, fish account for more than 20% of protein intake (PAI 1995). In some developing countries and among some population segments in developed countries, terrestrial wildlife also continues to be an important subsistence resource. In some
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areas of Botswana, for example, over 50 species of wild animals provide as much as 40% of the protein in the diet; and in Nigeria, game accounts for about 20% of the animal protein consumed by people in rural areas (McNeely and others 1990). Increased diversity of livestock can sometimes improve productivity. In Africa, for example, "game ranching"—in which wild species of antelope replace domesticated livestock on particular ranches—can result in higher yields of meat than could be obtained from domesticated animals (WRI 1987). Naturally diverse ungulates can use grassland resources more efficiently than domesticated varieties in these situations. In rural Alaska, more than 90% of the people harvest and use wild animals for both food and clothing. The cash value of wild food constitutes 49% of residents' mean income (ADFG 1994). The marine mammals of the northern Bering, Chukchi, and Beaufort seas are among the most diverse in the world; many of the species are used for subsistence purposes by Alaskan Natives, and many have important symbolic roles in cultural identity (NRC 1994). Most of the world's timber production still comes from nondomesticated systems, although a growing share is now harvested on plantations. In tropical forests, for example, the area of plantations increased from 18 million hectares in 1980 to 40 million in 1990. Although statistics on the world value of internal and externally traded timber products are not available, the world value of forest-product exports alone in 1993 was to $100 billion (FAOSTAT 1995). Recreational uses of biodiversity—fishing, hunting, and various nonconsumptive uses, such as bird-watching—also contribute to the economy (see Everglades and Boulder, Colo., case studies in this chapter and Lake Washington case study in chapter 6). In the United States alone, such activities involved about 77 million persons over the age of 16 in 1996 and resulted in expenditures of $101.2 billion (DOI/DOC 1997). Wildlife watchers made up the largest group (62.9 million participants in 1996); their expenditures included $16.7 billion for equipment, $9.4 billion for travel, and $3.1 billion in other expenses. Of a total of 39.7 million sportspersons, 35.2 million were adult anglers and 14.0 million were hunters; this group spent $72 billion in 1996, including $37.8 billion for fishing, $20.6 billion for hunting, and $13.5 billion in unspecified expenses (DOI/DOC 1997). One of the most rapidly growing values of biodiversity in wild ecosystems is related to tourism. Worldwide receipts from international tourism in 1990 totaled $250 billion (WCMC 1992), and domestic tourism is believed to be as much as 10 times higher. How much of the tourist trade is attracted specifically by biodiversity is difficult to tell. Of the $55 billion in tourism revenues accruing to developing countries in 1988, an estimated 4–22% was due to "nature tourism" (Lindberg 1991). More than half of the visitors in Costa Rica, for example, state that the national parks are their "principal reason" for traveling to the country (see the case study on Costa Rica in chapter 2). Costa Rica's protected areas are estimated to account for $87 million annually in tourism revenues.
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As in domesticated agroecosystems, the diversity of genes and species undergirds the continued productivity of these components of biodiversity in nondomesticated ecosystems. The genetic diversity in a species provides the basis for the species to adapt to changing environmental conditions. Reduced genetic diversity increases the probability of species extinction or of substantial reductions in the population of a species due to changing environmental conditions (such as, a change in climate or the introduction of a new disease). For example, wild exotic trout in the western United States can be destroyed by whirling disease, which is caused by the microorganism Myxobolus cerebralis; the only way to restore infected populations is to find genetically resistant populations (Hoffman 1990). The productivity of an ecosystem can be high both in systems with large numbers of species, such as tropical forests, and in systems with relatively small numbers of species, such as wetlands. The extirpation of the California sea otter from much of its range in the 1800s resulted in substantial changes in near-shore ecosystems (Estes and Palmisano 1974). Recovery of otter populations to their original densities affects other ecosystem components of commercial or recreational value: giant kelp, sea urchins, abalone, and surf clams. The sea otter is a primary predator (top of the food chain) of mollusks and urchins, which graze on stands of algae that are primary producers (of calories consumed) in coastal regions extending from California through the Aleutian Islands. As a consequence of the extirpation of sea otters, grazing urchins became common and reduced the biomass of primary producers. Just like the loss of specific species, the manipulation of the food chain structure can alter the productivity of direct value to humans. For example, in areas where intense gillnet fisheries have seriously depleted Nile perch stocks, many African cichlids have recovered in Lake Victoria (Kaufman 1992). Equivalently, the introduction of the Nile perch into Lake Victoria led to the extinction of many species of the native cichlid fish and substantially reduced the total harvest of this important food source (Johnson and others 1996). Biodiversity in the Pharmaceutical and Biotechnology Industry Wild species of plants and animals have long been the source of important pharmaceutical products. Natural products play a central role in traditional healthcare systems. The World Health Organization estimates that some 80% of people in developing countries obtain their primary health care in the form of traditional medicines (Farnsworth 1988). Systems of ayurvedic medicine (traditional Hindu medical practices) in India and the traditional systems of Chinese herbal medicine, for example, reach hundreds of millions of people. Total sales of herbal medicines in Europe, Asia, and North America were estimated at $8.4 billion in 1993 (Laird and Wynberg 1996). That total is not large on a global
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scale, but sales of herbal medicines can often be an important source of income for local communities and business. Natural products also continue to play a central role in the pharmacopeia of industrialized nations. Of the highest-selling 150 prescription drugs sold in the United States in 1993, 18% of the 150 consisted of essentially unaltered natural products, and natural products provided essential information used to synthesize an additional 39% (Grifo and others 1997). In total, 57% owed their existence either directly or indirectly to natural products. Natural products were once the only source of pharmaceuticals, but by the 1960s synthetic chemistry had advanced to the point where the pharmaceutical industry's interest in natural products for drug development had declined greatly and it declined further with the introduction of "rational drug design". Several technological advances led to a resurgence of interest in research in natural products in the 1980s. The development of modern techniques involving computers, robotics, and highly sensitive instrumentation for the extraction, fractionation, and chemical identification of natural products has dramatically increased the efficiency and decreased the cost of screening for natural products. Before the 1980s, a laboratory using test-tube and in vivo assays could screen 100–1,000 samples per week. Now, a laboratory using in vitro mechanism-based assays and robotics can screen 10,000 samples per week. Where the screening of 10,000 plant extracts would have cost $6 million a decade ago, it can now be accomplished for $150,000 (Reid and others 1995). In the next decade, throughput could grow by a factor of 10–100. As the new technologies became available in the 1980s, many companies established natural-products research divisions. Of 27 companies interviewed in 1991, two-thirds had established their natural-products programs within the preceding 6 years (Reid and others 1993). In most large pharmaceutical companies, natural-products research accounts for 10% or less of overall research. But some smaller companies now focus exclusively on natural products. For example, Shaman Pharmaceuticals bases all its drug-discovery research on natural products used in traditional healing systems, and it currently has two drugs in clinical trials. How long the interest in natural-products drug discovery will last is impossible to know. New techniques of combinatorial chemistry and other advances in drug design might reduce interest in natural-products research. Even so, many chemists feel that current synthetic chemistry is still unable to match, the complexity of many of the natural compounds that have proved effective as drugs. For example, paclitaxel, known as Taxol, a compound from the Pacific yew tree (which is not considered economically important for timber or other commercial purposes), is being used in treatment for ovarian and breast cancer. The compound was discovered in the 1960s but could not be synthesized until the 1990s; and even now, the process is so time-consuming and expensive that natural precursors are used in the production of the drug.
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Drugs developed from natural products often generate large profits for drug companies, but the actual value of biodiversity as a ''raw material'' for drug development is much smaller (Simpson and others 1996). On the average, some $235 million and 12 years of work are required to produce a single marketable product in the drug industry. Moreover, less than 1 in 10,000 chemicals is likely to result in a potential new drug and only 1 in 4 of those candidates will make it to the pharmacy. On the basis of typical royalties paid for raw materials, the likelihood of discovering a new drug, the length of patent protection, and the discount rate, the present net value of an arrangement whereby a nation contributes 1,000 extracts for screening by industry would be only about $50,000. Moreover, there would be a 97.5% chance that no product at all would be produced. The likelihood that any particular plant or animal will yield a new drug is extremely small, but endangered species in the United States have yielded new drugs. We can to some degree aggregate the plants and animals that are most likely to lead to new drugs. These are likely to have considerable value as prospects (Rausser and Small in press). Biotechnology Until recently, pharmaceutical, agricultural, and industrial uses of biodiversity relied on largely different methods of research and development. Today, with the help of the new biotechnologies, individual samples of plants or microorganisms can be maintained in culture and screened for potential use in any of those industries. Companies are screening the properties of organisms to develop new antifouling compounds for ships, new glues, and to isolate new genes and proteins for use in industry. A thermophilic bacterium collected from Yellowstone hot springs provided the heat-stable enzyme Taq polymerase, which makes it possible, in a process known as polymerase chain reaction (PCR), to amplify specific DNA target sequences derived from minute quantities of DNA. PCR has provided the basis of medical diagnoses, forensic analyses, and basic research that were impossible just 10 years ago. The current world market for Taq polymerase, is $80–85 million per year (Rabinow 1996). Biodiversity is the essential "raw material" of the biotechnology industry, but the process of examining biodiversity for new applications in that industry has only begun. Biodiversity and Bioremediation It has become clear in recent years that the fundamental role of microorganisms in global processes can be exploited in maintaining and restoring environmental productivity and quality. Indeed, microorganisms are already playing important roles, both in the prevention of pollution (for example, through waste processing and environmental monitoring) and in environmental restoration (for example, through bioremediation of spilled oil). Modern biotechnology is pro-
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viding tools that will enhance the environmental roles of microorganisms, and this trend should accelerate as the appropriate basic and applied sciences mature (Colwell 1995; Zilinskas and others 1995). A variety of probes and diagnostics for monitoring food and environmental quality have been developed (Dooley 1994), and there is much discussion of the development of genetically engineered organisms for speeding the clean up of wastes, spills, and contaminated sediments. Furthermore, marine biotechnology is being pursued avidly and on a larger scale in Japan (Yamaguchi 1996), where one major goal is to find ways to lower global atmospheric CO2 concentrations. Without doubt, the prediction of climate change will be much improved by a better understanding of global cycles, and the tools of marine biotechnology will be heavily involved in this endeavor. The fundamental premise here is that chronic pollution reduces system species diversity and diminishes ecosystem function. Thus, restoring perceived environmental quality and productivity cannot easily be separated from basic biodiversity issues. Ecosystem Services A substantial risk of undesirable and unexpected changes in ecosystem services is posed when the abundance of any species in an ecosystem is changed greatly. Our ability to predict which species are important for particular services is limited by the absence of detailed experimental studies of the ecosystem in question. Nonetheless, the available data indicate that a higher level of species diversity in an ecosystem tends to increase the likelihood that particular ecosystem services will be maintained in the face of changing ecological or climatic conditions (below, "Species Diversity and Ecosystem Services"). Both wild and human-modified ecosystems provide humankind with a variety of services that we often take for granted (see box 3-1). The services include the provision of clean water, regulation of water flows, modification of local and regional climate and rainfall, maintenance of soil fertility, flood control, pest control, and the protection of coastal zones from storm damage. All those are "products" of ecosystems and thus a product of biodiversity. The characteristics and maintenance of these ecosystem services are linked to the diversity of species in the systems and ultimately to the genetic diversity within those species. However, the nature of this relationship between ecosystem services and biodiversity at the lower levels of species and genetic diversity is complex and only partially understood. Biodiversity and Ecosystem Services Humankind derives considerable benefits not only from the products of biodiversity but also from services of ecological systems, such as water purification, erosion control, and pollination. The relationship between biodiversity and
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BOX 3-1 Types of Ecosystem Services Linked to Biodiversity Atmospheric—Climatic Gaseous composition of the atmosphere Moderation of local and regional weather, including temperature and precipitation Hydrological Water quality and quantity Stream-bank stability Control of severity of floods Stability of coastal zones (through presence of coastal communities, such as coral reefs, mangroves, or seagrass beds) Biological and Chemical Biotransformation, detoxification, and dispersal of wastes Cycling of elements, particularly carbon, nitrogen, oxygen, and sulfur Buffering and moderation of the hydrological cycle Nutrient cycling and decay of organic matter Control of parasites and disease, pest control Maintenance of genetic library Habitat and food-chain support Agricultural Crop production, timber and biomass energy production, pollination Stabilization of soils Economic and Social Support of human cultures Aesthetic value and ecotourism SOURCE: Adapted from Daily 1997. ecosystem services is complex and will be discussed in greater detail later, but in general, most ecosystem services are degraded or diminished if the biodiversity of an ecosystem is substantially diminished. Because most ecosystem services are provided freely by natural systems, we typically become aware of their value and importance only when they are lost or diminished. Historically, ecosystem services were not generally scarce and management decisions were rarely based on their low marginal value. That is decreasingly true, particularly with regard to drinking-water quality, flood control, pollination, soil fertility, and carbon sequestration. This trend is prompting interest in developing institutional frameworks through which to restore and safeguard these services in the United States and internationally.
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The cost of the loss of various ecosystem services can be high. The US National Marine Fisheries Service estimated that the destruction of US coastal estuaries in 1954–1978 costs the nation over $200 million per year in revenues lost from commercial and sport fisheries (McNeely and others 1990). Hodgson and Dixon (1988) calculated the cost of the potential loss of the service that the forested watershed of Bacuit Bay in the Philippines provides in preventing siltation of the coastal coral ecosystem. The forest prevents siltation: if it were cut, siltation would increase, thereby reducing tourism and fisheries revenues. In a scenario in which logging is banned in the basin, the net present value of a 10-year sum of gross revenues from all three sources would be $42 million. In a scenario of continued logging, the net present value would be only $25 million. One recent and controversial set of global estimates of the value of ecosystem services is discussed in chapter 5. The value of various ecosystem services can also be seen in the costs that must be incurred to replace them. For example, natural soil ecosystems help to maintain high crop productivity, and the productivity that is lost if soil is degraded through erosion or through changes in species composition can sometimes be restored through the introduction of relatively expensive fertilizers or irrigation. Forested watersheds slow siltation of downstream reservoirs used for hydropower; a forest is altered and sedimentation increases, the hydroelectric power generating capacity lost could be replaced through the construction of new dams. Wetlands play important roles as "buffers", absorbing much stream runoff and preventing floods; if wetlands are filled, their flood-control role could be assumed by new flood-control dams. The US Army Corps of Engineers estimated that retaining a wetlands complex outside Boston, Massachusetts, realized an annual cost savings of $17 million in flood protection (McNeely and others 1990). The conversion of one type of habitat to another—such as a conversion of natural forest to agriculture or of agricultural land to suburban development—can dramatically affect a wide variety of ecosystem services. Historically, the impacts of such conversions on ecosystem services have not received attention from policy-makers and managers, for two main reasons. First, the relationship between an ecosystem and a service is typically poorly understood. The conversion of a park to a parking lot will obviously change patterns of water runoff, but other effects of habitat conversions are difficult to predict. For example, the replacement of native vegetation in the western Australian wheatbelt with annual crops and pastures reduced rates of transpiration, increased runoff, and consequently raised the water table, creating waterlogged soil. Salts that had accumulated deep in the soil salinized the soil surface. The saline wet conditions altered ecosystem services by reducing farmland productivity and reducing the supply of freshwater. Restoring such degraded ecosystems can take decades and be accomplished at high cost. In addition, the changes threatened the remaining fragments of
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the toxins of poison dart frogs is providing insight into fundamental neural mechanisms. Such new insights and tools came not from our imaginations but from observations of other peoples and other species. Even with the dazzling power of modern molecular biology, is it reasonable to expect that we can imagine all the new solutions that can be devised? The diversity of life supplies us not only with new tools and techniques, but also with the inspiration to imagine innovations. "There are more things in Heaven and Earth, Horatio, than are dreamt of in your philosophy" (Shakespeare, Hamlet, act I, scene V). Biodiversity holds the potential for us to understand ourselves better. We have developed profound insights about our own culture and society through the study of other peoples. Likewise, we can learn about our physiology through the study of other species. Many of our insights about ourselves could only have come through the study of other species. For example, our knowledge of our development and reproduction rests on the study of many diverse species beyond the common laboratory species, such as bacteria, nematodes, rats, mice, and monkeys. It had long been presumed that testosterone is necessary for mating behavior in males—except possibly in humans—because it was the case for all animals that had been studied. However, the discovery that this was not the case in the red-sided garter snake showed that the correlation between testosterone and behavior in vertebrates was not, after all, axiomatic (Joy and Crews 1988). The zebra fish has recently proved to be an especially useful model for understanding the molecular genetics of neural development (Brown 1997). Even plants reveal important cues to our physiology. Research on the circadian clock of the mustard plant (Arabidopsis) has led to techniques for studying circadian clocks in animals in more detail and with greater precision than ever before possible (Kay 1996). Considerable advances in understanding of the human nervous system have come from studying nonhuman vertebrates and invertebrates. For example, the nematode Caenorhabditis elegans has provided insights into nervous disorders and diseases, such as Alzheimer's disease. Biodiversity has often served as an early-warning system that has foretold threats to human health before sufficient data had been collected to detect effects directly. Rachel Carson's (1962) Silent Spring, for example, established a strong case against the use of pesticides primarily on the basis of threats to wildlife populations. The same pesticides have since been found to present serious public-health risks. Similarly, declines in populations of the common seal in the Wadden Sea and reproductive failure in the Beluga whale in the St. Lawrence River in Canada might stem from the ingestion of PCB-contaminated fish—if so, caution should be used to ensure the safety of marine food supplies for human consumption (Chivian 1997). Wildlife studies have shown evidence of effects of various chlorinated organic compounds on the immune systems of animals (reviewed in Repetto and Baliga 1995) and on their reproductive physiology (Colborn and others 1993).
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The evidence is much less conclusive that these compounds have an effect on human physiology, but the accumulation of evidence from wildlife studies points to the need for more-detailed research on possible effects on humans. Much of the study of biodiversity might have no immediate applied value, but it is valuable nonetheless. It is impossible to predict how new knowledge will be used. Knowledge about various forms of life has, as seen in the above examples, had direct effects on improving human health and has led to revolutions in science, such as our understanding of molecular genetics. Few people in Darwin's time would have imagined how his fascination with animal variation would transform the study of biology and so profoundly alter our notions. Bacterial genetics was an obscure field of research in the 1950s, but it led directly to what we now call molecular biology. Even the small cadre of bacterial geneticists could not have known how their research would revolutionize biology and medicine. Transformation Biodiversity can transform our values in the sense that experiences with and knowledge of biodiversity provide opportunities for self-knowledge—knowledge of our own values, attitudes, and beliefs and our place within life as a whole. Although we often regard our natural environment as either a means or a hindrance to such ends as satisfying our physical needs and accumulating material goods, our interactions with our environment also develop our sense of aesthetic pleasure, our curiosity, and our sense of where we fit in the broader scheme of things. A biologically diverse environment offers broad opportunities for developing new ways of appreciating one's place, the scope of one's enjoyments, and oneself (Kellert and Wilson 1993; Norton 1986; Wilson 1984). Sometimes, the contributions of biodiversity are indirect: knowledge expands experience, as evident in a comment made by a recent graduate of an adult literacy program in Washington, DC: "You know, I never even cared about the trees in my neighborhood until I read about how they grow." Children who are exposed to activities and direct experiences with wildlife gain more than knowledge about wildlife. Their attitudes change (Hair and Pomerantz 1987). They become more concerned about wildlife in general; that is, about wildlife in other parts of the world. There is a small but growing literature on how experience with wildlife—and especially with wilderness and outdoor recreation—influences values, beliefs, and attitudes (Finger 1994; Hendee and Pitstick 1993; Kaplan and Talbot 1983; Orams 1996; Rossman and Ulehla 1977; Shearl 1988; Shin 1993). One's conception of self is related to nature in highly symbolic ways. Few Americans wish to live in the kind of society that poisons the Bald Eagle, our symbol of national strength and pride. The grandeur of the symbol is enhanced by the opportunity to watch the Bald Eagle in flight. Conversely, the symbolic
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power of the eagle would inevitably be diminished if there were no eagles living in the wild. People are motivated by more than the satisfaction of their physical needs; they are moved by the possibility of expanding their horizons—both their own experience and also knowledge "for its own sake". The experience of biodiversity provides such opportunities. The examples cited above suggest that diverse environments contribute to a self-knowledge that, although it can take a multitude of forms and is difficult to catalog, is nonetheless irreducibly valuable in its own right. Aesthetics To superkill a species is to shut down a story of millennia and leave no future possibilities [Holmes Rolston III, quoted in Natural History 1996, p 75]. Many people develop a deep aesthetic appreciation for biodiversity and its components. This appreciation has several dimensions, including an appreciation of how biodiversity reveals the complex and intertwined history of life on Earth and a resonance with important personal experiences and familiar or special landscapes. In addition to moral, ethical, and religious values, there also are deeply intellectual reasons for conservation of biodiversity; chapter 4 reviews these in detail. The Copernican revolution was an intellectual breakthrough that changed our view of ourselves. The self-awareness that comes from knowledge of biodiversity is only beginning to be realized. Biodiversity ultimately arises from the fact that there has been one evolutionary history of life on Earth, with vertical (through time) inheritance. It follows that the species present today have unique histories. There are many definitions of organic evolution, but two that are especially relevant in this connection are "descent with modification" (Darwin) and "accumulated history" (Salthe). Species contain the histories of their lineages. It is the concept of lineage that is central to the imagery of evolution, and the vast panoply of life through time has become part of our culture. Equally central is the notion of relationship: some pairs of lineages are more closely related than others, in the sense that they have a more recent common ancestor. There are now well worked-out methods for assessing degree of phylogenetic relationship and for reconstructing the history of life on Earth. These developments have made it possible to express values in new ways. Sense of Place Long-branch taxa frequently have played special cultural roles or have been recognized as having intrinsic value (Dworkin 1994). The Ginkgo tree was saved
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from extinction in Buddhist monasteries because of a concern that is moral and cultural in origin. It now has a "sense of place" value in many parts of the world. Surprisingly, this is a case in which other values also come into play, in that Ginkgo extracts now constitute one of the most widely used medicines in Europe, prescribed by German medical doctors to over 10 million patients annually. Many writers have noted that biodiversity, especially the habitats of native and indigenous species, helps to root not only plants but also people by giving them a sense of place. As noted in chapter 2, it is a characteristic association of species that usually leads us to categorize a place. Indeed, some have suggested that the conservation of landscapes is the best remedy we might have to counter the transience, or rootlessness, that has become one of the most salient characteristics of American society. For example, Wallace Stegner (1962) wrote about American rootlessness and restlessness especially in the American West. He understood the lure of freedom in the absence of obligation. But that rootlessness, Stegner wrote, has often been a curse. Our migratoriness has hindered us from becoming a people of communities and traditions, especially in the West. It has robbed us of the gods who make places holy. It has cut off individuals and families and communities from memory and the continuum of time. Gary Snyder (1996) and Carolyn Merchant (1992) have suggested that our ethics and by implication the value we place on biodiversity, must be grounded in an understanding of local habitats and the functioning of ecosystems. This work, especially Leopold's notion of a "land ethic" has inspired work in both environmental philosophy and social psychology; the latter has indicated that concern with the intrinsic value of biodiversity is widespread in the United States (Karp 1996; Stern and others 1993, 1998). A sense of place is founded on relationships—for example, with nature, with the past, with future generations, and with those with whom one shares responsibility for maintaining the essential character of one's surroundings (Gussow 1972). To belong to or in a landscape, one must feel connected to its past, both natural and human. One is then aware of the moral obligation to cultivate the landscape in ways that maintain its identifying characteristics so that future generations can recognize it as one does now. The work of protecting native flora and fauna establishes a continuity with the future through a consistency with the past. Thus, we maintain a connection with a landscape through time (Cronon 1991; Worster 1985). The effort that we make to protect the habitats of native species entrenches a relationship between people and places. One sees one's own activities and those of one's community as rooted in a particular place; one's experiences, in other words, depend on where one is (Gallagher 1993; Light and Smith 1998). The protection of biodiversity is often the catalyst that turns generic locations into distinct places. The difference is that a place is a location that we have
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filled with meaning and thus have claimed with our feelings. History, natural or human, insofar as we claim it as our own, must be imbedded in places that we cherish in shared memory and whose symbols we maintain and respect. Native and indigenous species are living parts of our community history (Baily 1915). (See the case study below on Boulder, Colo., open space.) Space is the symbol of freedom in the western world; it is a frontier to conquer; it is the potential, not the actual. It is an ever-receding horizon. Place, in contrast, involves commitment and responsibility, actuality rather than potential. It is not the realm of conquest, but the sphere of concern and conservation. The reintroduction and protection of native species, in contrast, follows Virgil's counsel: It is well to be informed about the winds, About the variations of the sky, The native traits and habits of the place, What each locale permits and what denies. Much of what many people deplore about the human subversion of nature—and fear about the destruction of the environment—has to do with the loss of places that they keep in shared memory and cherish with collective loyalty. Many fears stem from the loss of the particular—the specific characteristics of places that make them ours—and so from the loss of the security one has when one is able to rely on the lore and the love of places and communities that one knows well. The beauty and majesty of nature have always affected human beings: we take pleasure in perceiving nature's beauty, and we feel wonder and awe at its enormous scale (the starry skies) and its dynamic power (a hurricane). The aesthetic categories of the beautiful and the sublime, which became prominent in the writings of 18th-century philosophers, apply to our understanding of the value of biodiversity today. Plants and animals in their intricate and functional design are beautiful; we perceive that beauty with pleasure. We garden; we cut flowers for our homes; we keep birds, fish, and many other animals in our homes; we frequent zoos; and so on. Ecotourism is based largely on people's enjoyment of natural beauty. Artists celebrate that beauty in paintings and sculptures drawn from nature. Indeed, nature is the primary object of representation in art and a constant theme of poetry. The record of evolution stretches the limits of our understanding and imagination. Those who study this record—paleontologists, zoologists, ecologists, botanists, and many others—discover in every kind of plant and animal a story worth telling, a complex tale of adaptation that exemplifies evolutionary processes. About 99% of the species that have ever existed on Earth are now extinct, and the ones that exist today are the latest descendants and deeply reward study for the historical record that they contain. No less than the artifacts of great civilizations gone by, rare species descended from organisms that lived eons ago possess a historical value and authenticity that demand attention and apprecia-
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tion. When we take pleasure in the qualities of these organisms—when we enjoy simply knowing and perceiving them with no further use or application in mind—we are engaged in the experience of the aesthetic. Case Study: Boulder, Colo., Open Space The city of Boulder, Colo., lies at the intersection of the eastern face of the Rocky Mountains and the western edge of the Great Plains in an area of high diversity of mountain and prairie species. The citizens of Boulder, an affluent educated community, have long valued and protected its natural setting, most recently by establishing the so-called blue line, a contour at the city's western edge above which no development is to be extended, and by approving an increase in the city sales tax of 0.4% to buy and protect land adjacent to the city as open space. Boulder now has the highest per capita acreage of municipally owned natural area of cities in the United States. The purposes of open space, as codified in a charter amendment approved by voters in 1986, are preserving and restoring natural areas and their biota, preserving land for passive recreational use, retaining traditional agricultural land uses, limiting urban sprawl, and preserving aesthetic values (City of Boulder Open Space Department 1995). Loss of natural areas to urban sprawl is proceeding rapidly throughout most of the region around Boulder, and there have been attempts to curtail the open-space program, initiated primarily by the real-estate, development, and general business communities in the Boulder Valley. However, care has been taken to get city council and general public support and involvement during all phases of land purchase and policy implementation. Public-opinion polls conducted in 1994 and 1995 indicate that although conservation of biodiversity is a factor in public support for open space, the primary purpose in the minds of most people is to keep urban and suburban sprawl at bay (Miller 1994; Miller and Caldwell 1995). It is clear that, to the great majority of Boulder's population, the value of open space as natural viewscape exceeds the value of the same land for possible commercial and residential development. In recent years, the Open Space Department has begun shifting its emphasis from the purchase of new land to the development of management plans that will ensure its ecological integrity into the future. Of particular concern is the increasing use of open space for outdoor recreation (Zaslowsky 1995). Two issues illustrate the growing conflicts between the value of Boulder open space as a biodiversity reserve and its value as a template for outdoor recreation. The first involves closing a trail to protect the high biodiversity of habitats and replacing it with a nearby trail. The second involves an attempt to implement leash laws in some areas where dog owners traditionally had been permitted to walk their pets
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off-leash. In both cases, the managers in the Open Space Department recommended restricting, but not prohibiting, recreation uses. Neither the users nor those who favored protection were satisfied. Those examples suggest three general lessons about the challenges that managers of suburban open spaces can expect to face. First, it is more difficult to impose restrictions on the use of open space after its establishment than at the time of its establishment. Second, hard data on the consequences of recreation on the biodiversity of open space will be helpful in resolving conflicts. Third, the ecological integrity of suburban open spaces will persist only if citizen users can be educated as to the consequences of their collective impacts. It is a daunting educational challenge. Public participation has long been an integral part of the planning process regarding Boulder open space. The relative success of the program is attributable largely to deliberate efforts to integrate public opinion and participation into the decision-making process. Ethics and Religion Very often, people value biodiversity for ethical and religious reasons. These reasons are often part of a comprehensive ethical or cosmological world view that, on the one hand, is anchored in a self-conception or identity and, on the other hand, is supported by an interpretative tradition and the communities that share it. Such values—and the worldly points of reference that support them—are held not in the form of needs or preferences, but rather as judgments that attach to identity. One does not "choose" these values; they are the deeply held values that form our identity. Summary In this chapter, we have discussed how the many dimensions of biodiversity and its components contribute to decisions on management of biodiversity. The goods and services, present and potential, that humans derive directly or indirectly from biodiversity can be viewed from different social and cultural perspectives. The case study examples of the Everglades and Boulder illustrate why a broadened understanding is necessary for management considerations. In the next chapter, we see that information on the many philosophical and systematic approaches to valuing biodiversity can favor particular outcomes in management decisions. Knowledge of these value systems can broaden a manager's ability to resolve conflicts and to understand differences among parties involved in management decisions.
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Representative terms from entire chapter: