Invasion theory aims to understand patterns of species spread and success in new environments to find solutions towards mitigating the damaging effects of invasive species. The successful establishment of invasive plants is often attributed to large-scale natural or anthropogenic disturbances while disturbances caused by small-scale human activities, like plant resource collection and individual forest management practices, are rarely accounted for in invasive plant models. In this study, we examine the effects of individual land use and resource collection (tablet collected data of individually identified sites of plant collection, management activities, and recreational use), historic land degradation, and natural disturbances on invasive species abundance in four dominant forest types in the bufferzone community forests of Chitwan, Nepal. This research addresses the following questions: (1) Do current land use and small-scale human activities contribute to species invasion? (2) Do the historical, biophysical and disturbance factors contributing to invasive plant spread differ by species? We evaluated invasive plant abundance for 2219 evenly distributed 10mX5m plots in 21 community forests.
Results/Conclusions
The most abundant invading plants in the study site are Mikania micrantha and Chromolaena odorata occupying 39% and 52% of the plots, respectively. These dominant invaders are influenced by distinct ecological drivers and occupy sites with unique overstory species. We found that management activities such as forest cleaning and burning may provoke invasive species and aid in their dispersal and establishment. Mikania was positively correlated (p=0.04) with areas of ‘jungle cleaning’ in the Dalbergia sissoo mixed forest. The management activity, ‘jungle cleaning,’ could be exacerbating the growth and abundance of invasive plants by decreasing other native plants in the area. In Shorea robusta forests, Mikania abundance was positively correlated with recent locations of fires. In all forest types, Mikania was significantly correlated with the presence of at least one other invasive plant. Areas with mutual co-occurrences of invasive species may be at greater risk for continued invasion or eventual severe effects on biodiversity and ecosystem functioning. Determining the factors that contribute to invasive plant establishment and spread in these forests will enhance our understanding of the invasion process and help to identify individual management or resource collection activities that could be unintentionally enhancing invasive plant success.