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Harvard Forest Symposium Abstract 2008

  • Title: Regional and historical effects on the distribution and abundance of an invasive herb
  • Primary Author: Kristina Stinson (University of Massachusetts - Amherst )
  • Abstract:

    The susceptibility of a site to invasion by nonnative species depends on its current ecological features and its historical land use. This study investigated the distribution of an invasive herb, garlic mustard (Alliaria petiolata), in historically wooded or historically cleared forested sites in two regions of Massachusetts with distinct ecological characteristics. Using GIS and historical records, the presence and absence of garlic mustard was surveyed at randomly selected 100 x 25 m presently forested study sites with known 1830’s forest cover history (open or wooded) in the Connecticut River Valley and the Housatonic River Valley. A significantly (p<10-10) higher proportion of these random survey sites contained garlic mustard in the Housatonic River Valley than in the Connecticut River Valley, while there was only a marginally significant (p=.057) difference in garlic mustard presence among sites with different 1830 land use. Among sites that contained garlic mustard—both random survey sites and 9 previously known sites—ANOVA showed that land use history, but not ecoregion, was a significant determining factor in the amount of garlic mustard present, with bigger populations in sites that were open in 1830. Thus, the ecologically distinct factors of each region appear to primarily determine the number of sites colonized, while land use history determines performance within colonized sites. This suggests that for garlic mustard, historical land use is not facilitating initial establishment, but rather serves as a cause or indicator of environmental quality for proliferation of the invasion. It also suggests that mechanisms of dispersal may differ in the two regions.

  • Research Category: Historical and Retrospective Studies, Invasive Plants, Pests & Pathogens