Biogeochemical impacts of the northward expansion of kudzu under climate change: The importance of ecological context

Abstract

Climate change is generally expected to push plant species to higher latitudes and elevations; how the climate-induced migrations of disruptive invasive species may affect higher-latitude ecosystems has not been widely examined. Kudzu (Pueraria montana) has large impacts on nitrogen (N) cycling and trace N gas emissions in the southeastern United States. To underst and how its projected northward migration under climate change will impact ecosystems in the northeastern United States, we examine the impacts of kudzu in the Mid-Atlantic region, near kudzu's northern invasion front. We pair plots invaded by kudzu with adjacent uninvaded plots, and examine rates of leaf litter decomposition, soil nitrogen pools and net cycling rates, N trace gas emissions, and microbial dynamics. Kudzu litter has more N and decomposes faster than litter from co-occurring species. Unlike in Georgia, near the center of kudzu's current range in the United States, kudzu invasion in the Mid-Atlantic has very small ecosystem impacts, causing significant increases only in the sizes of soil nitrate pools. These Mid-Atlantic ecosystems may be buffered against invasion impacts, creating a lag between changes in the plant community and biogeochemical changes. A combination of factors, including time since establishment, soil types, growing season length, and temperatures, may limit kudzu's biogeochemical impacts along its invasion front. © 2013 Hickman and Lerdau.