. Critical trends in Illinois ecosystems. Ecological assessment (Biology); Environmental impact analysis; Nature; Pollution; Conservation of natural resources; Environmental quality. 86 Critical Trends in Illinois Ecosystems Bobcats, which have been sighted in Randolph and Madison counties since the 1980s, require extensive and varied terrain and cover region in and around the Sinkhole Plain still boasts a liandful of sizable forested tracts — the two largest are about 1,250 acres each — along the Mississippi and Kaskaskia rivers. However, the mean size of surviving tracts of contiguous forest
. Critical trends in Illinois ecosystems. Ecological assessment (Biology); Environmental impact analysis; Nature; Pollution; Conservation of natural resources; Environmental quality. 86 Critical Trends in Illinois Ecosystems Bobcats, which have been sighted in Randolph and Madison counties since the 1980s, require extensive and varied terrain and cover region in and around the Sinkhole Plain still boasts a liandful of sizable forested tracts — the two largest are about 1,250 acres each — along the Mississippi and Kaskaskia rivers. However, the mean size of surviving tracts of contiguous forested bottomland is 19 acres, vastly smaller than the 500 acres thought to be the minimum-sized woods capable of sheltering nesting songbirds. The 173. acres of loess hill prairie iii the region is split into 12 sites. The more than 3,000 emergent wetlands include a few large ones on the Mississippi near the former site of Valmeyer and near Fults, but the mean size of emergent wetlands is only acres. Hydrology - Paving once-porous surfaces and installing storm drains concentrates runoff from rains and melting snow, making bigger floods out of less water. The lower Kaskaskia River has always tended to flood. Carlyle Lake was built in 1969, 50 miles upstream from the Kaskaskia's confluence with the Mississippi, to catch and hold water that used to overwhelm downstream parts of the valley. The lake has caused noticeable reductions in peak water flow downstream. Carhle not onl\ lowers flood peaks but boosts flows during droughts when water is released from the reservoir. The remodeling of the watershed in and around the Sinkhole Plain has tended to aggravate the effects of drought. Drained farm fields speed the flow of water into nearby streams. This water used to soak slowly into the soil, building up subsoil moisture that fed streams for weeks or months. As a result, droughts that once merely reduced flow through the regions upland creeks now cause them to dr>' up complet
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