Invasive plant management, white-tailed deer and nonnative earthworms are associated with understory plant community structure in forests in north-eastern North America

Premise Land managers spend substantial resources on managing invasive species because of their implication in ecological degradation and economic costs. However, management of invasive species is seldom coupled with empirical assessments of management outcomes or the ecological impacts of the target species. Additionally, the study of invasive species has, until recently, neglected to acknowledge co-stressors on native communities, which often are the drivers of ecological degradation. Methods We evaluated the independent and combined effects of <i>Vincetoxicum rossicum</i> (pale swallow-wort) management, white-tailed deer and non-native earthworms on forest understory plant communities in New York State Parks. Results During the study period, management and fencing significantly decreased the abundance of <i>V. rossicum.</i> However, management did not result in increased native plant cover or diversity. Native plant cover, diversity and evenness were all negatively associated with invasive earthworm biomass. Composition of plant communities was associated with both management and earthworm abundance, but fenced and open plots did not differ after two years of exclosure. Conclusions Continuous monitoring is needed, in particular to evaluate the potential role of invasive earthworms as a driver of ecological change. Further management coupling reduction of deer abundance with active transplanting of native species is required to restore native plant communities.