Invasion of exotic plants has increasingly deteriorated forest health, decreased forest productivity, degraded wildlife habitat, and diminished biodiversity.  It has been suggested that early detection and treatment are the keys to minimize efforts and costs to best defense against these invasive plants.  In order to identify areas with high invasion possibilities for constant surveillance, we investigated the landscape scale distribution patterns of nonnative invasive plants in forest ecosystems, and analyzed factors that influence the distribution of invasive plants in southern U.S.  Exotic invasive plants data from the USDA Forest Inventory and Analysis (FIA) were used in this study.  In this study, we analyzed the association between county level percentage of infested forest plots and its related environmental and disturbance factors, which included road density, population-interaction index, land cover diversity, forest connectivity, forest cover percentage, average elevation, and slope. 

Results/Conclusions

A total of 33 nonnative plants and groups, including trees, shrubs, vines, grasses, and ferns, has been observed in the southern 13 states in U.S.  The results show that road density, land cover diversity, forest connectivity, and elevation in the forested area, and forest cover percentage in the county have significant influences on exotic invasive plants distribution.  For all of the significant variables, invasive plants have the highest occurrence in the middle ranges, which indicates that the invasion of exotic plants is most likely to occur in areas with medium level disturbances.