. Critical trends in Illinois ecosystems. Ecological assessment (Biology); Environmental impact analysis; Nature; Pollution; Conservation of natural resources; Environmental quality. 102 Critical Trends in Illinois Ecosystems The cypress- tupelo forest and the associated species of the swamps and sloughs are found only in the basin and are totally dependent upon the natural hydrologic cycle of the Cache River the Cache corridor. Nests of forest-dwellers in the basin, such as the yellow-billed cuckoo and indigo bunting, suffer more than 60% losses to predators. Losses are lower in the larger wooded tracts. Non-native species - Many of the plants that grow in the basin were introduced to the area, although the Cache River basin does not suffer infestations as severe as other parts of Illinois. Autumn olive is a significant problem throughout the area, and in the Cache River Natural Area in particular Black locust, planted to enrich depleted soils and to provide firewood, is a pest in such areas as the Halesia Nature Preserve.. Altering water tlow - No change made in the past 190 years has affected the ecosystem more drastically than the reordering of the presettlement hydrology undertaken to cure the areas chronic flooding. These alterations speed the flow of water from where it falls into the nearest stream channel. Rushing the water downstream has caused massive bank erosion and gullying in the Upper Cache River channel and led to excessive sedimentation and channel aggregation in the Lower Cache River Natural Area. The continued gully formation and deepening of stream channels drains wetlands (e.g.. Bird Spring Pond, Heron Pond), whose eleva- tion becomes significantly higher than the stream channel because of channel bed scour Draining wetlands takes away the natural water control func- tions they provide, such as slowing moving water and moderating the extremes of flood and drought. It also diminishes habitat for migrating geese, bald eagles, and other waterfowl.