Distribution and abundance of invasive plant species along the Appalachian National Scenic Trail in Pennsylvania

Background/Question/Methods

To effectively manage the biological integrity of nature reserves and parks, natural resource managers must know the location and magnitude of damaging forces. Invasive plant species are a contemporary and spatially broad threat to biological integrity in ecosystems throughout the world. The status of this threat, however, is largely unknown in many areas managed for uses that include the maintenance of biodiversity. During summer 2014, we conducted a survey of invasive plant distribution and abundance along the Pennsylvania section of the Appalachian National Scenic Trail, otherwise known as the Appalachian Trail (A.T.), to guide management of this resource by identifying areas of highest relative threat to biodiversity. Points of invasion were collected geospatially and considered independent if they were separated by a trail distance of 30 m. We also collected environmental variables that are possible predictors of invasion location and size, which we are actively in the process of analyzing.  Here, we report preliminary results for the four most abundant plant species: Alliaria petiolata, Berberis thunbergii, Microstegium vimineum, and Rosa multiflora.

Results/Conclusions

We documented 2622 points of invasion along the 370 km of the PA-A.T., or 7.1 points km^-1, for the four species included in this analysis. The total points and points km^-1 were highest for Microstegium vimineum (53% of all points; 3.8 points km^-1)^. Average area of individual invasions differed across species (p <0.0001), being largest for Microstegium vimineum (7.6 ±0.5 m²) and lowest for Alliaria petiolata (1.6 ±1.0 m²). Based on the number and size of independent points of invasion, we conclude that Microstegium vimineum currently poses the largest threat to the biological integrity of the forest understory along the PA-A.T. We are actively analyzing these data to understand environmental patterns of invasion and the efficacy of using easily collected environmental data to predict areas vulnerable to future invasion and proliferation. The lead author (an undergraduate) assumed the role of principle investigator, and the other authors (established scientists) acted as advisors. We took this strategy to maximize the undergraduate's growth as an ecologist.