Development of a preliminary vegetation-based indicator of ecosystem health for coastal wetlands of the Laurentian Great Lakes

Abstract

Wetland plants, due to their sedentary nature, hold great potential for use as indicators of ecosystem condition in the Great Lakes. However, natural variations in lake levels have historically confounded efforts to create such indicators. Our goal was to use zone-level vegetation data collected over a seven-year period of low to high water levels to overcome these difficulties and identify metrics capable of accurately reflecting disturbance despite lake-level variation. Through a combination of multivariate statistical analyses and a review of the literature, we identified and tested a series of plant-based metrics for wet meadow, emergent, and submergent zones of lacustrine coastal wetlands of Western Lake Huron. These were combined into zone-specific indicators of ecosystem health, which were then applied to wetlands of the remaining Great Lakes to assess basin-wide viability. The resulting indicators were found to reflect disturbance without bias towards high or low water levels. While they must be assessed for use in riverine and barrier-beach coastal wetlands before full-scale implementation can occur, we suggest their use on a preliminary basis in monitoring and management efforts.