PARENT SESSION
Poster Session # 5: GIS and Remote Sensing.
Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
GIS-based estimates of former isolated depressional wetlands in an agricultural landscape.
McCauley, Lisa*,1, Jenkins, David2, 1 University of Illinois at Urbana-Champaign / IL DNR, Springfield, IL2 University of Illinois at Springfield, Springfield, IL
ABSTRACT- Before European settlement, 23% of Illinois (8 million acres) was covered by wetlands. Currently, only 3.5% of original wetlands (1.25 million acres) exist in Illinois, this is a loss of an estimated 90% of the state's wetlands. Champaign County was one of the most extensively drained counties in the State: 40-61% of its pre-settlement area was covered in wetlands: today only 0.9% of its area is covered by wetlands (i.e., 39-60% of original county area was drained), and 98% of the wetland number. We used GIS to map the spatial extent, density, pattern, and sizes of drained and extant depressional wetlands in Champaign County, Illinois. We derived several models of former wetlands; models used digital soil maps to identify hydric soils, but varied by using 10 m and 30 m Digital Elevation Models (DEM), Digital Raster Graphics (DRG), or Digital Orthophoto Quadrangles (DOQ). We also conducted visual field surveys for saturated or ponded conditions to test the models. Our most reliable model to date is based on DRGs and hydric soils, and indicates that circa 900 depressional wetlands (75% of number, 69% of area) were drained, accounting for 868 ha of lost wetland habitat in Champaign County alone. Thus, depressional wetlands accounted for the majority of historical wetland loss. Nearest-neighbor distances have dramatically changed, so that an organism adapted to disperse in the former landscape could reach 72% of all nearest neighbors within 500 m. Today, that probability never exceeds 23%, even at 3000 m distance. The modern, drained landscape of Champaign County poses potential risk for remaining wetland populations, and GIS models of precise former wetlands locations can be valuable for wetland conservation and restoration efforts.
Key words: wetland loss, spatial statistics, isolated depressional wetlands, GIS