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Harvard Forest Symposium Abstract 2005
- Title: Responses of a New England forest community to increasing levels of invasion
- Primary Author: Kristina Stinson (University of Massachusetts - Amherst )
- Additional Authors: Luke Durbin (Illinois Wesleyan University); Sylvan Kaufman (Adkins Arboretum); Frank Lowenstein (The Nature Conservancy)
- Abstract:
Few studies have empirically tested whether biological invasions negatively affect native plant communities, and how these impacts may differ with respect to the severity of the invasion. We combined two years of vegetation sampling with experimental removal treatments to assess the community-level responses of a New England forest to invasion by the Eurasian biennial Alliaria petiolata (garlic mustard). We conducted vegetation censuses across twenty-four plots ranging from low to high invasive cover, and experimentally removed 0%, 50% or 100% A. petiolata from adjacent, highly invaded plots at the same study site. The Shannon Diversity Index declined linearly with increasing in situ densities of A. petiolata, and increased in response to full (but not partial) removal of garlic mustard at the experimental plots (Fig. 1). In both cases, higher diversity was related to increased species equitability, rather than species richness, indicating that garlic mustard cover directly alters the composition, rather than total number of species in the community. Our observational and experimental studies further demonstrated that the cover, relative densities and/or absolute abundances of native plants declined with higher abundance or cover of A. petiolata, including three native functional groups (herbs, sedges, and tree seedlings) the typical understory herb, Viola papilionacea and four dominant tree species (Fig. 2). Our results provide both correlative and empirical evidence that medium-to-high garlic mustard invasion reduces tree seedling abundance and native species diversity via changes in species composition. Managers may wish to implement full or partial removal depending on whether their priorities emphasize diversity or absolute abundances of certain species.
- Research Category:
