Why Conserve Biodiversity?




	8.7 WHY CONSERVE BIODIVERSITY? Direct use value / Indirect use value / Option value / Economic valuation Functional and Intrinsic Value-- We do not know how many species live on planet Earth; therefore it is not surprising that we do not know what the ecological role of each of them. Perhaps there is a relationship between stability and complexity, whereby ecosystems with more species are more stable. In most cases, we cannot predict with certainly the effects of the loss of one or more species from an ecosystem. The changes may be minor if the functional role of the absent species can be compensated for by another species (i.e., if there is overlap or spare capacity in the system). However, removal of a species upon which others depend (perhaps because it is an important food item), may lead to a chain reaction and the loss of many other species. Ideally, this uncertainty would mean we should adopt the precautionary principle: i.e., act carefully to ensure that we preserve all species. Many people believe that biodiversity and natural landscapes are 'good things' with intrinsic or inherent value. This variety has non-use values for humans through enrichment of culture, religion or aesthetics, and should be preserved. However, this view is by not held by all. What is the value of biodiversity? Direct Use Value-- Biodiversity can provide resources of direct value to humans when it is consumed or turned into a marketable product. Biodiversity can be used directly as food (e.g., Mekong fisheries: see Section 12), a source of medicines, as agents of biological control of pests, and as a source of industrial materials (e.g., wood, rubber, dyes) and genetic raw material for new agricultural varieties. Recreational harvesting (for the pet and aquarium trade) and ecotourism come under this category also. Indirect Use Value-- Biodiversity provides services that are essential to the well being of the ecosystems that they make up and upon which humans depend. These can be regarded as 'free' in that they are not traded in markets. This category includes the many organisms that form the base of food chains that support fisheries, and the insects that pollinate agricultural crops and other plants. Forests have an indirect use value in the maintenance and generation of soil cover, and their influence on hydrology through river flows and flooding. The use of organisms for genetic research that can eventually be applied to benefit humans is another indirect use of biodiversity. Option Value-- Once extinct, species are lost forever. Humans may place value on the option of retaining biodiversity for direct or indirect use in the future. This may be viewed as the intergenerational value of biodiversity through the heritage it represents for future generations. Economic Valuation-- At present, policy-makers tend to treat water as a free resource, and do not take account of its indirect use value as a 'public good' on which rivers, floodplains and their biodiversity depend. Realistic economic valuations of rivers and other inland waters will be an essential first step toward a change in attitudes. Constanza et al. (1997) estimated the values of direct use of biodiversity (e.g., food in the form of fishes), indirect use (as ecosystem services), and cultural considerations. A global value of US$6,579 x 109/year was estimated for all inland waters. It exceeded the worth of all other non-marine ecosystems combined (US$5,740 x 109/year), despite the far smaller extent of inland waters. This is because the average per unit area value of rivers (US$8,498/ha) and wetlands (US$14,785/ha) far exceeds the most valuable terrestrial ecosystems (forest US$969/ha; grasslands US$232/ha). Although there are uncertainties in these estimates, the value of inland waters is certain to increase in future as ecosystem goods and services (especially unpolluted fresh water) become more stressed and scarce.