The importance of biodiversity to the health of our planet is increasingly being discussed, not only by scientists, but by the public at large. Therefore, an understanding of how human activities are affecting biodiversity is vital for informed participation in society, and thus it is an important topic for liberal arts education. Here, I present the protocol and results for a field activity that I have used in a non-majors' biology course to investigate the influence of anthropogenic disturbances on plant communities. Students surveyed plant-species abundances in five sites that had experienced a range of disturbance regimes, including protected nature trails, mowed fields, and a ruderal (waste) site. Disturbances had a negative impact on measures of species richness, evenness, and diversity; moreover, disturbances made the plant communities much more susceptible to invasion by alien species. While the approach taken in this study worked very well in my non-majors' course, it could easily be adapted and refined for use in ecology, conservation, and botany courses for biology majors.