Examines a problem of growing concern and importance: obtaining accurate estimates of the ecological costs of human activities. This text covers a range of subjects, from the management and function of ecosystems to ecological issues affecting public policy. It focuses on the trade-offs inherent in environmental and conservation policy. Ecosystems provide resources that can be extracted and are valued in the market place, but the delivery of those resources depends on the functioning of natural processes whose maintenance may involve substantial costs. The book discusses the fundamental structure and behaviour of ecosystems and evaluates the tools employed by economists to value ecosystem goods and services not commonly bought and sold in existing markets. In addition, it examines the possible use of ecological risk assessment to link ecological and economic approaches. This text should be of interest to ecologists, foresters, geographers, natural resource economists, park managers and graduate students.