Effects of road salt and Phragmites australis invasion on the vegetation of a western Massachusetts calcareous lake-basin fen

Kampoosa Bog in Stockbridge, Massachusetts, US;A is a 70-ha wetland compris ed of calcareous basin fen and red maple swamp bordered, in part, by roads including the Massachusetts Turnpike. High salt concentrations in the groun d water (due to the application of deicing salts on the Turnpike) and Phrag mites australis colonies appear to be impacting the native vegetation at th is site. Sodium and chloride concentrations at Kampoosa Bog are generally b elow previously published threshold levels for impacting vegetation, althou gh such levels vary by species and in relation to other environmental stres s conditions. Giant reed (Phragmites), a salt-tolerant invasive species, in vaded the northern portion of the wetland adjacent to the Turnpike and a ga s pipeline sometime after they were built in the 1950s. By 1998, Phragmites had formed dense colonies that continued to spread across the wetland, whi ch supports several state-listed rare plant and animal species. High salt c oncentrations (Na+ > 112 mg/L, Cl- > 54 mg/L) are present up to 300 meters from the Turnpike. Phragmites colonies occur in areas with high and low sal t concentrations, and the species abundance is not well-correlated with ele vated salt levels. Although high salt concentrations and Phragmites abundan ce do not seem to produce an interaction effect on the vegetation of the we tland, the graminoid fen community is impacted by both factors separately. We attribute decreases in the abundance of species between invaded and non- invaded areas to the presence of Phragmites. In the graminoid fen, we attri bute decreases in both community measures (richness, evenness, and overall cover) and individual species abundances to high salt concentrations.