In seeking ways and means to use economic methodology to support conservation of biological resources, it is necessary to have a clear understanding of the major threats which biological resources face on the ground and in the water. It can be seen that most of these threats have an economic foundation. Major threats include:

• Habitat alteration, usually from highly diverse natural ecosystems to far less diverse (often mono-culture) agroecosystems. This is clearly the most important threat, often related to land-use changes on a regional scale which involve great reduction in the area of natural vegetation; such reductions in area inevitably mean reductions in populations of species, with resulting loss in genetic diversity and increase in vulnerability to disease, hunting, and random population changes (Soule and Wilcox, 1980).
• Over-harvesting, the taking of individuals at a higher rate than can be sustained by the natural reproductive capacity of the population being harvested; when species are protected by law, harvesting is called "poaching."
• Climatic change, often related to changing regional vegetation patterns; involves such factors as global carbon dioxide build-up, regional effects, such as "El nino" and monsoon systems, and local effects, often involving fire management.

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