Purdue University Graduate School
Ashley Kovach-Hammons - May 2022.pdf (6.91 MB)


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posted on 2022-04-26, 18:03 authored by Ashley M Kovach-HammonsAshley M Kovach-Hammons

 Kudzu (Pueraria montana) is an invasive woody vine widespread throughout the  southeastern United States, with recent studies predicting that its habitat will expand northward.  New occurrences and recent studies using climatic parameters suggest that the Midwestern  region of the United States is at the greatest risk of kudzu invasion. As there have already been  25 reports of kudzu within the Great Lakes basin, and no previous landscape models exist for the  basin, I developed probability models from existing spatial data (land cover, hydrology, geology,  annual precipitation, elevation, aspect, and known kudzu locations) using generalized additive,  bioclimate envelope, and maximum entropy methods. I further expanded each model to include  the basin and a 2.25-degree buffer in order to include 193 reported kudzu sites. For each  predictive model, I determined the area under the curve (AUC) for a receiver operating  characteristic curve (ROC) comparing false positive and false negative rates. I performed field  surveys at eight known sites of kudzu presence in Michigan, Indiana, and Ohio. Each presence  site was paired with a control (known kudzu absence site). I collected environmental data  including canopy cover, volumetric soil moisture, soil pH, litter depth, midstory species diversity  and diameter at breast height (DBH), and overstory basal area. Each environmental measure was  compared between kudzu presence and control survey sites as well as between in-basin and out?of-basin survey sites using a two-way ANOVA. Maximum entropy models produced the highest  AUC in both the basin and buffer models during model development. These models showed that  urban and disturbed habitats resulted in the greatest probability of potential habitat for kudzu. I  found no statistically significant differences in environmental characteristics between kudzu  absent and presence sites or between in- and out-of-basin sites, suggesting kudzu might be  dispersal-limited rather than limited by environmental characteristics. Continuing existing  management and further monitoring of kudzu spread is likely necessary to limit further  introduction and to mitigate spread of kudzu within the Great Lakes region.  


Degree Type

  • Master of Science


  • Biological Sciences

Campus location

  • Fort Wayne

Advisor/Supervisor/Committee Chair

Jordan Marshall

Additional Committee Member 2

Mark Jordan

Additional Committee Member 3

Bruce Kingsbury