Environmental Control of Wetland Plant Communities

We have determined hydrologic regimes at a variety of sites while conducting studies to identify factors controlling wetland plant community composition and distribution. We have had relatively little trouble determining hydrologic regimes that result in wetland communities as opposed to what we considered to be upland or aquatic communities. However, defining a hydrologic regime that consistently resulted in a particular type of wetland plant community has proven much more elusive. In practice, we have not found that a knowledge of the hydrologic regime provides a sufficient basis for determining what wetland plant communities should exist on a site. Nor does a wetland plant community define the site's hydrologic regime. We have found that a knowledge of substrate characteristics and site history, particularly where man's influences have been present, are also necessary to understand the composition and distribution of wetland plant communities.