Sedimentation of Prairie Pothole Wetlands: The Need for Integrated Research by Agricultural and Wildlife Interests
Introduction
Spatial position and morphology of prairie wetlands in agricultural fields make them highly vulnerable to sedimentation (Neely and Baker 1989). Sediment is the most important pollutant of surface waters in the United States and the greatest source of sediment is erosion of agricultural lands (Robinson 1971; Long 1991; Wayland 1993). Impacts of suspended sediment and accelerated sedimentation on fish and aquatic life in riverine systems have been intensively studied (Ritchie 1972; Newcombe and MacDonald 1991; Waters 1995), but the influence of sediment on prairie wetland ecosystems is largely unknown. Sediment input from agricultural fields on prairie wetlands is of particular concern because these wetlands provide critical habitat required by breeding, migrating, and resting waterfowl (Batt et al. 1989), shorebirds (Eldridge 1987), and other wetland-dependent wildlife (Duebbert 1981). In addition to high wildlife values, wetlands are valued for flood control (Brun et al. 1981; Ludden et al. 1983), ground-water recharge (Winter 1989), and other societal values (Stevens et al. 1995).
A few studies have examined the influence of agricultural land-use on sedimentation of prairie wetlands (Adomaitis et al. 1967; Martin and Hartman 1987; Dieter 1991; Dryer et al. 1996), but impacts on water quality, primary productivity, and aquatic food webs are poorly understood (Gleason and Euliss 1996). Soil erosion is a primary concern of agricultural interests because erosion reduces the integrity, productivity, and sustainability of agricultural lands (Timmons 1980). Agricultural research and policy have been instrumental in developing and implementing agricultural conservation practices on private lands that reduce soil erosion, in order to maintain productivity and enhance soils and water quality. However, the success of conservation practices is normally evaluated from an agricultural perspective and generally does not include wildlife considerations (Miranowski and Bender 1982). Integration of goals from multiple interests and disciplines in conservation policies is in line with recent political emphasis on developing holistic agricultural programs (Gerard 1995). The amalgamation of pertinent interests and disciplines into research programs will ensure that appropriate information is available to policy makers.
Here we present an overview of research on the influence of agricultural land-use practices on sedimentation rates in prairie wetlands, and discuss potential effects of sedimentation on wetland ecology. We also discuss management strategies that reduce sediment inputs into prairie wetlands and the need to integrate research by wildlife and agricultural interests to develop holistic management strategies.
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