SEDIMENTATION OF PRAIRIE WETLANDS UNDER CHANGING CLIMATIC CONDITIONS: IMPLICATIONS FOR WETLAND-DEPENDENT AVIFAUNA

Agriculturally driven environmental change and global warming are major concerns in the conservation of prairie wetland landscapes, and in turn, for the conservation of wetland-dependent avifauna. Climate change models predict a warmer, wetter future for much of the Prairie Pothole Region (PPR), with warmer winters, earlier springs, and increased winter precipitation particularly in the eastern PPR. Concurrent with a warming climate is the search for new energy technologies, and investment in biofuels has already increased the number of tilled acres throughout the PPR. Changing climate and increased agricultural production will have a direct impact on the millions of pothole wetlands that wetland dependent birds rely upon for foraging, brood rearing, and refueling during migration. Changing climate will affect water budgets and resulting habitat conditions, while changing land use and precipitation patterns will increase erosion and wetland sedimentation.

As a tool for conservation, we are developing spatially explicit models to forecast the extent of erosion and wetland sedimentation in regions of the Great Plains of North America under future scenarios of precipitation, temperature, and land use. We are using the Revised Universal Soil Loss Equation, which is based on rainfall, erosivity, soil type, topography, and land use, to model sediment deposition into prairie wetlands. The amount of sediment entering wetlands (sediment delivery ratio) is inferred from empirical studies. Models use projections of future precipitation and temperature on an 8-km grid from downscaled climate models using IPCC4 scenarios. To understand the implications of wetland change for migratory birds, we are building, refining, and applying spatially explicit landscape scale niche models for wetland dependent birds, including long-distance migrant sandpipers refueling in the prairie pothole region of North America. Under the climatic conditions of the past decade, millions of en route calidridine species foraged in seasonally flooded wetlands in the drier agricultural areas within the PPR, the wetland type most threatened by sedimentation.