Muskrat (Ondatra zibethicus) effects on wetland plant communities

Session: Wetland Restoration in the Great Lakes Basin: Research and Innovation (3)

Zi Xun Kua, SUNY-ESF, [email protected]
John Farrell, SUNY-ESF, [email protected]
John Stella, SUNY-ESF, [email protected]

Abstract

Water regulation in the Upper Saint Lawrence River has restricted the natural fluctuation of the river and reduced winter water levels. This has induced degradation of the regional coastal habitat, expansion of invasive cattails and decline in local muskrat (Ondatra zibethicus) populations. Muskrats rely on adequate winter water depths for foraging and have been shown as a sensitive bioindicator for hydrologic changes. Muskrat activity, including house construction, herbivory, and intensive grazing areas (“eat-outs”) generally increase wetland habitat heterogeneity, enhance local wetland plant diversity, and create additional niches for other species. We conducted a field study in wetlands along the St. Lawrence River to investigate the effects of muskrat herbivory and structure building on local wetland plant biodiversity. Multivariate analysis showed that wetland plant assemblages differed between muskrat-disturbed and reference areas. Species richness, diversity, and community similarity were greater in muskrat disturbed areas than in reference plots. Interactions between site cattail cover and soil moisture influenced species richness. The results from this study will help improve our understanding about the impact of muskrats on the health and diversity of wetland communities and inform best wetland management practices.