Impacts of Roads on Non-native Plant Invasions

Plant invasions can often be attributed to human influences such as roadways and land-uses. It is not clear if roads and land use have a combined influence that can exacerbate plant invasions into forests. Additionally, variation in invasion patterns among forest regions could be better explained by potentially differing influences from roads and land-use. I hypothesized that roads aid plant invasions into forests by allowing invasive plants to establish along adjacent roadsides. Additionally, impacts of land use can exacerbate the road effects (i.e., number of invasive plant species & distance of invasive plants from a road). Here, using data from the Forest Inventory and Analysis (FIA) national program (n = 25,416), I examined the road effect on invasive plants in different landscapes in the Eastern U.S. (EUS). The results showed that, in general, invasive plant richness decreased as distance from a road increases. Additionally, forests associated with land uses such as agriculture and development have higher invasive plant richness pressure and larger road effects (measured in distance) than forests in more natural settings. Examining the road effect under different landscape settings proves to be a strong indicator of the influence humans have on plant invasions