N-fixation by kudzu (Pueraria montana): impacts on nitrogen cycling and soil microbial communities by an invasive vine.
Jonathan
Hickman, SUNY-Stony Brook, hickman@life.bio.sunysb.edu
Manuel
Lerdau, SUNY-Stony Brook, manuel.lerdau@sunysb.edu
(Presenting)
Among invasive plants, those that fix nitrogen (N) present a clear threat to the integrity of native ecosystems. Kudzu (Pueraria montana) is a legume that has become highly invasive in the U.S., and is known to fix N in its native range. Kudzu's tendency to form dense stands and its extensive coverage in the southern U.S. may increase rates of N cycling and accumulation in soils, potentially leading to changes in community composition, soil acidification, and increased fluxes of trace N gases and leached nitrate to neighboring ecosystems. We present data on the effects of kudzu invasion on nutrient cycling and microbial communities for sites in the McKee-Beshers Wildlife Management Area in Montgomery County, Maryland. Two pairs of sites were selected for sampling; each pair consisted of invaded and uninvaded sites in close proximity, with similar slopes, aspects, and land-use histories. Soil samples were collected from each site and analyzed for extractable nitrate and ammonium, net N mineralization, net nitrification, denitrification enzyme activity, and microbial biomass. Preliminary results suggest striking effects of kudzu invasion on ecosystem processes, with large increases in N-cycling parameters occurring in the invaded sites.