Graduation Year


Graduation Month


Document Type


Degree Name

Bachelor of Science

School or Department

Forestry and Conservation


Environmental Science and Sustainability

Faculty Mentor Department


Faculty Mentor

Rebekah Fields

Subject Categories

Biodiversity | Weed Science


For the capstone project with the University of Montana Davidson Honors College, I investigated the diversity index of grassland and rangeland plots across the state of Montana. My study, conducted from June to August 2023, includes data collected by my team. The purpose of this research project was testing the hypothesis that the diversity index decreases in plots containing invasive grass species.

During the summer of 2023, the Spatial Analysis Lab surveyed over 1000 plots in rangelands and grasslands across the state of Montana to locate an invasive grass, Ventenata dubia. Data collected includes species identification, ocular estimates of coverage, native, introduced, or invasive status, and location data. My study uses Simpson’s Diversity Index to estimate diversity for the surveyed plots and to compare the index for plots containing native and invasive species. Simpson’s Index uses the total number of organisms within a study area and their relative abundance to estimate the biodiversity in that area.

Out of the 1,314 samples that were taken, 54% of them included invasive species. It was found that for plots containing invasive species, the average Simpson’s index value was .542 and the standard deviation was .19. These numbers indicate that there is a moderate amount of diversity and also a moderate amount of variability within the plots that include invasive species. In comparison, 46% of samples that were taken did not contain invasive species. The Simpson’s index value for this data set was .536 and a standard deviation of .19, showing a moderate amount of diversity and a moderate amount of variability. The data does not support the hypothesis that the presence of invasive species decreases diversity. While the available data does not provide sufficient grounds for definitive conclusions, we cannot outright dismiss the hypothesis due to the absence of a baseline for diversity unaffected by introduced or invasive species. This challenge arises because Montana grasslands have undergone such significant alterations that locating truly pristine systems is exceedingly difficult.

The outcomes underscore the need for strategic conservation efforts, including continuous monitoring and prompt management actions, to preserve the ecological balance and maintain the resilience of Montana's grasslands.

Honors College Research Project


GLI Capstone Project




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