Historical Introduction Routes of Invasive Plants to Pennsylvania

Invasive species are a growing issue throughout the United States. Non-native invasives directly compete with native species for resources, such as light, nutrients, and space. Invasives also can be detrimental to the ecosystem, agriculture, and infrastructure. To approach limiting the spread of invasive plants, a thorough examination must be made to examine how they spread from areas of introduction. This study will use herbarium records to identify historical routes of invasion and the abiotic/biotic conditions conducive for invasion; the ultimate goal of this research is to identify high-risk corridors/habitats for future invasions. Additionally, these historical records can be used to determine if different plant growth forms (i.e., woody, herbaceous, or vining) have differing modes of invasion. In the present study we document several invasive plants introduced to Pennsylvania through intentional cultivation, including the Bradford pear (Pyrus calleryana), Autumn Olive (Elaeagnus umbellate), English Ivy (Hedera helix), Kudzu (Pueraria montana), Orange daylily (Hemerocallis fulva), and Periwinkle (Vinca minor). These species will be used as models to map historical invasions and predict high-risk habitat for future invasion. This research is timely and important as cultivation of exotic species still occurs, presenting continued potential for invasion.