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.
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."
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