Lake Erie coastal-wetland vegetation: community composition and spatial and temporal variation over a twelve-year period

Abstract

Lake Erie’s coastal wetlands have rich plant communities, but they are subject to a variety of anthropogenic threats, from coastal development to invasions by non-native species. Vegetation data collected from wetlands along the entire lakeshore from 2011 to 2022 as part of the Coastal Wetland Monitoring Program were analyzed to document the plant species present in these wetlands, to determine frequencies of occurrence of these species, and to seek spatial patterns and/or temporal trends in community composition. During this period, 58 wetlands were sampled, many of them multiple times. In total, 310 species were recorded, and the mean per-site richness was 23.7 species, although the distribution was right-skewed, ranging from four species to 58. Wetlands in the western basin of the lake tended to have lower species richness than those further east. Several of the most common species were non-natives, such as Common Reed (Phragmites australis) and Eurasian Watermilfoil (Myriophyllum spicatum), although the large majority of the 48 non-native species encountered were quite uncommon, being observed during 5% or fewer site visits. There were no temporal trends in total or non-native species richness, but frequency of aquatic (submergent and floating-leaved) species increased over time, likely as a result of a significant, multi-year rise in lake level over the study period.