Ecological Characteristics of County Drains in the River Raisin, Michigan

[摘要] Agricultural drainage is widely implemented throughout the U.S. to improve landdrainage and increase crop productivity, affecting as much as 50% of cropland area inMidwestern states. Many of the headwater streams of this region are managed understate laws by drainage districts, county drain commissioners or similar entities. Theecological condition of these streams is sparsely documented but considered poor. Ievaluated ten stream reaches, each of which contained a segment managed under theMichigan Drain Code and an unmanaged segment (;;natural”), using a paired reachsampling design. Habitat quality was significantly lower for seven of nine rapidassessment metrics and for overall habitat quality. Other physical characteristicsincluding woody debris, substrate particle size and sinuosity were all greater in naturalreaches. In comparison to natural reaches, county drains were significantly incised andwere nearly straight in planform. Biological assessment using macroinvertebratesindicated slightly improved scores in natural reaches but differences were not significantfor most metrics. A regression of biological metrics against habitat quality that includeddata from a wide variety of streams within the watershed reveals poorer biologicalcondition in both stream types than would be expected from habitat alone, suggesting thatthese systems are challenged by additional stressors.

[发布机构] University of Michigan

[效力级别] Agricultural Drainage

[关键词] River Raisin;Agricultural Drainage;School of Natural Resources and Environment