Investigating the ecology of native and non-native lianas in Central and Western New York

Abstract

Woody vines, also called lianas, are increasing in abundance in temperate forests of the Northeastern United States. Both native and invasive taxa can alter community trajectories and affect ecosystem function, but invasive taxa such as oriental bittersweet (Celastrus orbiculatus) and Asian wisterias (Wisteria floribunda; Wisteria sinensis), are particularly problematic. Questions remain regarding whether these lianas are passengers or drivers of ecological change where they occur. To analyze the effects of invasive lianas in Central and Western New York, I constructed a two-part study. In the first portion of my research, I performed a selective liana-removal experiment within two local forests that contain infestations of C. orbiculatus and Wisteria floribunda. Over three growing seasons, I measured the effect of lianas on native tree-growth by comparing trees that had no history of liana-infestation to trees that were either still infested or had lianas cut. The impacts of liana treatment varied according to the initial trunk size and species of infested tree, with some evidence for negative impacts in a situationally-dependent manner. Overall, while mature tree growth was not impacted by lianas to the extent I predicted, future impacts of lianas on forest succession may reveal their more dramatic effects. For the second portion of my research, I compared sites with plant communities that supported C. orbiculatus to those supporting its native congener, C. scandens, to analyze for possible landscape and community patterns that could help to explain the occurrence and abundance of both species. While landscape patterns and community structure were similar between Celastrus sites, those with the invasive C. orbiculatus tended to have higher dominance by exotics and lower floristic quality. These results suggest that the encroachment of other exotics with C. orbiculatus into sites with C. scandens may be a symptom of underlying habitat disturbance. By quantifying conditions that may encourage the spread of invasive lianas and their impacts once present in plant communities, I highlight the challenge of regional conservation in a rapidly changing world.