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 (C) 2010 Elsevier Ltd All rights reserved