Forest wildlife habitat statistics for Maine 1982 /

no.9

Forest wildlife habitat statistics for New Hampshire, 1983 /

no.9

Plant species indicators of physical environment in Great Lakes coastal wetlands

Plant taxa identified in 90 U.S. Great Lakes coastal emergent wetlands were evaluated as indicators of physical environment. Canonical correspondence analysis using the 40 most common taxa showed that water depth and tussock height explained the greatest amount of species-environment interaction among ten environmental factors measured as continuous variables (water depth, tussock height, latitude, longitude, and six ground cover categories). Indicator species analysis was used to identify species-environment interactions with categorical variables of soil type (sand, silt, clay, organic) and hydrogeomorphic type (Open-Coast Wetlands, River-Influenced Wetlands, Protected Wetlands). Of the 169 taxa that occurred in a minimum of four study sites and ten plots, 48 were hydrogeomorphic indicators and 90 were soil indicators. Most indicators of Protected Wetlands were bog and fen species which were also organic soil indicators. Protected Wetlands had significantly greater average coefficient of conservatism (C) values than did Open-Coast Wetlands and River-Influenced Wetlands, but average C values did not differ significantly by soil type. Open-Coast and River-Influenced hydrogeomorphic types tended to have sand or silt soils. Clay soils were found primarily in areas with Quaternary glaciolacustrine deposits or clay-rich tills. A fuller understanding of how the physical environment influences plant species distribution will improve our ability to detect the response of wetland vegetation to anthropogenic activities

Forest wildlife habitat statistics for Vermont, 1983 /

no.10

Wetland Invasion by Typha×glauca Increases Soil Methane Emissions

Wetland invasion by monotypic dominant plants can alter the physicochemical and biological properties of soils that affect methane emissions, a potent greenhouse gas. We examined the effects of Typha × glauca invasion on soil methane using laboratory incubation and controlled mesocosm experiments. Typha-invaded soils collected from three Midwestern (USA) wetlands had greater methane production potential during laboratory incubation than soils dominated by native wet meadow vegetation. Ten years post-invasion of native plant-dominated mesocosms, Typha increased methane emissions at least three-fold (native: 15.0 ± 10.5 mg CH4-C m−2 h−1, median: 6.1 mg CH4-C m−2 h−1; Typha: mean: 45.9 ± 16.7 mg CH4-C m−2 h−1, median: 26.8 mg CH4-C m−2 h−1) under high (+10 cm) water levels, though methane emissions were negligible under low (–10 cm) water levels. Methane emissions were positively correlated with soil carbon, nitrogen, and aboveground biomass, all of which were greater in Typha-invaded mesocosms. Together, our data suggest that replacement of large tracts of native wetlands throughout eastern North America with monocultures of invasive Typha could alter regional methane emissions