CONCEPTS: Biodiversity has many direct economic values related to species that
are bought and sold in the market place (e.g., forest, fishing, and rangeland
commodities), and many indirect values such as various kinds of outdoor
recreation that do not require direct harvest of species. By far the most valuable of these indirect
economic values are ecosystem services, such as maintenance of clean air and
clean water, which have been very undervalued by human societies. Biodiversity also has ethical values that
are not normally considered from the standpoint of economics.