The geography of ecosystem service value: The case of the Des Plaines and Cache River wetlands, Illinois

This paper explores the geography of ecosystem service benefits, the journey from ecosystem source to human beneficiary, using a comparative case study of the 2555 ha Cache River wetlands in rural southern Illinois and the 362 ha Des Plaines River wetlands in urban northeastern Illinois. Applying log-linear and exponential distance decay functions from source ecosystems to residents of zip code units yields annual economic values for the Cache River of $28,258–$2,548,793,956 and for the Des Plaines of $531,926–$216,284,749, with the Cache having greater value at shallow rates of spatial discounting and the Des Plaines at steeper rates. These extraordinarily wide ranges in estimated value highlight the essential importance of spatial discounting in ecosystem service valuation and, to a lesser extent, the importance of the spatial unit to which they are applied. They also highlight the dearth of empirical knowledge on the geographic context of ecosystem service values and the need to address critical research questions.

Research highlights
► The value of wetlands can vary by 2–3 orders of magnitude depending upon the definition of the economic jurisdiction.
► A small urban wetland can be more valuable than a large rural wetland if benefits are local.
► Zip codes and census tracts each have merits in applying spatial discounting of benefits.