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Harvard Forest REU Symposium Abstract 2005

  • Title: Demographic Attributes of the Invasive Species Alliaria petiolata at 3 Spatial Levels
  • Author: Marit L Wilkerson (The University of Texas - Austin)
  • Abstract:

    This study researched the role of landscape and habitat factors on demographic attributes of the invasive plant, Alliaria petiolata (garlic mustard), in Northeastern Forests. We surveyed the Prospect Hill tract at Harvard Forest and found that six invasive species, including garlic mustard, are most abundant in sites with agricultural land use history. We also monitored local populations of garlic mustard in sun, intermediate, and forest habitats at Harvard Forest over a period of three years. Using census data from four life-stages in 90 1m2 quadrants, we constructed demographic population matrices and found that population growth rate (λ) was greatest in sun populations and lowest in intermediate habitats. Survivorship between life-stages depended mainly on yearly fluctuation and less on type of habitat. The reasons for the higher λ of sun populations were higher seed production (p<.0001) and a higher survivorship from first- to second-year plants. At a broader scale, we surveyed public protected forests for presence of garlic mustard in two valley ecoregions of Western Massachusetts (Fig 1). We mapped each discrete population and recorded the percent cover of first- and second-year plants and distance of incursion into forested habitat. The two ecoregions differed in the percent cover of first-year plants (p=.0336) and in total percent cover of garlic mustard (p=.0279). The mean distance of incursion into the forest did not differ between regions (p=.8262). Our data used different spatial scales to show that garlic mustard invasion is influenced by landscape, habitat, and population characteristics.

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