ABSTRACT
Ecosystem services are produced free of charge, as outputs of ecosystem processes described in Chapter 5. Although humans, unlike other organisms, are capable of transporting services great distances, we still ultimately depend on food and water supplies that result from ecosystem processes. The only costs associated with our use of ecosystem services are those required for extraction and transportation, costs that are passed along from land managers and utilities to individual consumers. The costs of maintaining articially high densities of crop species in agroecosystems or of replacing ecosystem services that are lost as a result of ecosystem degradation, are generally ignored (Christensen et al. 2000).
