Evaluation of Forests and Native Vegetation for Nutrient and Sediment Management in Great Lakes Priority Basins

Abstract:

The use of native vegetation in strategic locations connecting the landscape to stream channels is one mitigation strategy used to reduce nutrient and sediment loads from current and legacy stores due to anthropogenic land uses. Planted vegetation has the capacity to limit the transport of materials through streambank stabilization, nutrient uptake, and by promoting greater water retention and nutrient storage deeper in sediment and soil profiles. This presentation evaluates bio-physical characteristics of landscapes to identify areas where re-establishment and conservation of existing forests and other native vegetation might provide reductions in excessive nutrient and sediment loading to the Fox River that enters Lake Michigan at Green Bay, WI. In addition, this work assesses how the spatial arrangement of these landscape and channel connectivity alterations influence these load reductions.

Geospatial tools are used to evaluate downstream nutrient loading scenarios based upon different land cover patterns. Existing geospatial data for soils, landform, slope, and land use that contribute to hydrologic and nutrient runoff in Great Lakes Priority Basins are used to evaluate areas where restored vegetation or its conservation may mitigate downstream transport of nutrients and sediment, thereby aiding efforts to reduce eutrophication risks. In addition, modeling scenarios consider land cover patterns that emphasize riparian buffers versus forest and native vegetation concentrated in the headwaters and other key runoff-prone areas. These models are applied and verified using field-based measurements to assess sediment and nutrient load reductions. Tradeoffs among the amount of land in native vegetation, the spatial arrangement of that area, and predicted changes in hydrologic and nutrient fluxes. Other considerations such as the retention of vegetated areas through park planning in the face of suburbanization and urbanization will also be presented. An in-depth stream study in one sub-basin and compiled literature data from other sub-basins are used to compare model predictions of water quality and trends to field observations.