Can the Conservation Reserve Program Increase Fish Diversity in Streams?

Voluntary private lands conservation programs such as the Conservation Reserve Program (CRP) have been used to achieve ecological goals such as improved fish population conditions. However there is a lack of data clearly demonstrating whether or not the desired ecological effects are realized with these programs. The present study incorporates the regional species pool concept to assess the effect of CRP lands on local fish species richness in streams of the Kaskaskia River Basin, Illinois. Species richness varies greatly among sites in response to a range of environmental variables as well as to the number of species there are in the area surrounding it (i.e. “neighborhood”), which makes detecting the effects of CRP difficult. Neighborhoods were delineated at varying waterway distances (5 – 40km) from a fish sampling site, and the species pool was estimated for each neighborhood by stacking individual species distributions predicted using random forests classification. We divided the local species richness by the neighborhood species pool to minimize the effects of environmental factors other than the proportion of CRP. This method allows us to better assess the benefits of CRP to stream fish diversity, and offers insight into how CRP can be more ecologically efficient.