Environmental Drivers of Plant Invasion in Wetland Mitigation

Abstract

Abstract Invasive plant species can alter natural communities and degrade ecosystem function, yet the factors influencing species invasion are poorly understood. The purpose of this study was to characterize important environmental drivers of plant invasions on wetland mitigation sites. We sampled vegetation and environmental variables (site hydrology, light availability, soil physiochemistry, site age) across invasion gradients at multiple wetland mitigation sites in the Coastal Plain and Piedmont physiographic provinces of Virginia. Data analysis involved a multi-metric statistical approach combining correlation, AIC, and CCA to arrive at a plausible model for invasion risk by species based on environmental correlates. We targeted Arthraxon hispidus (joint-head grass), Microstegium vimineum (Japanese stiltgrass), and Typha spp. (cattail), three invasive species that are known to be problematic on wetland mitigation sites in the region. Our analysis revealed species-specific environmental drivers of invasion with a few factors consistently important across all targeted invaders – notably, canopy cover (light availability), hydrology, and a handful of important physiochemical variables. The results of this research have been used to develop a suite of recommended best practices that can be implemented at the outset of a wetland mitigation project to reduce the risk of invasion.