Tracking Its Roots: Expansion by Japanese Stiltgrass (Microstegium vimineum(Trin.) A. Campus) in the Forestlands of Tennessee

Abstract

Invasions by non-natives contribute to the loss of ecosystem biodiversity and productivity, modification of biogeochemical cycles, and inhibit natural regeneration of native species. Japanese stiltgrass (Microstegium vimineum) is one of the most prevalent invasive grasses in the forestlands of Tennessee. Hence, we aim to identify potential determinants of invasion and quantify the relative importance of each factor. We analyzed extensive field data collected Forest Inventory and Analysis Program of the U.S. Forest Service to quantify the range expansion of Japanese stiltgrass from 2000 to 2011. We then identified potential factors influencing the likelihood of its presence using boosted regression trees. Our results indicated that the presence of Japanese stiltgrass on sampled plots almost doubled during this period (from 269 to 404 plots), spreading extensively, geographically. The probability of invasion was positively correlated with landscape features, forest features, and disturbance factors. Our results suggest that range expansion by Japanese stiltgrass will continue to expand in Tennessee. The efficacy of management practices can be guided by identifying these factors of invasions and reduce the likelihood of invasion.