Ecosystem services of restored wetlands and riparian buffers---USDA conservation practices in the glaciated interior plains

Wetlands provide valuable ecosystem services such as water quality improvement, carbon (C) sequestration, nutrient (nitrogen [N] and phosphorus [P]) retention, and biodiversity support. Throughout the Midwest, wetlands and riparian areas have been drained and cleared for conversion to row-crop agriculture. Through the United States Department of Agriculture, programs such as the Wetlands Reserve Program (WRP) and Conservation Reserve Program (CRP) provide landowners an opportunity to restore wetlands and riparian buffers with the goal of reintroducing ecosystem services lost during the conversion to agriculture. However, there has been little research on the effectiveness of WRP and CRP sites in returning ecosystem services to the landscape.;To fill this knowledge gap, I measured water quality improvement functions (denitrification and P sorption), C sequestration, and nutrient (N,P) accumulation in natural and restored wetlands and riparian buffers in Indiana and Ohio. I also evaluated which of three USDA conservation practices (e.g., restored wetland, restored riparian, conserved riparian) provided the greatest relative level of water quality improvement functions. I then characterized fine-scale spatial variability of denitrification and associated soil properties in natural and restored wetlands to determine if restored wetlands had comparable heterogeneity relative to natural wetlands.;Overall, riparian areas had higher rates of denitrification, P sorption, and C sequestration than depressional wetlands. Restored and natural riparian areas provided comparable services, whereas natural wetlands provided greater services than restored wetlands. Water quality improvement functions (N and P removal) were dependent upon the interactions between parent material (clayey vs. sandy soils), hydrologic connectivity (depressional vs. pulsed), and disturbance regime. First, greater connectivity to adjacent aquatic systems increased N and P removal and C sequestration. Second, finer-textured clayey soils facilitated greater denitrification and P sorption relative to sandier soils. Third, prescribed fires in the restored wetlands inhibited the accumulation of soil organic matter, which influences denitrification and P sorption. Continued enrollment of agricultural land into conservation practices will return ecosystem services to the landscape, although whether wetlands or riparian buffers should be restored will depend upon the desired ecosystem service.