Data on the association between garlic mustard and the plant community from a long-term observational dataset in Illinois, U.S.A.

The impact of a biological invasion on native communities is expected to be uneven across invaded landscapes due to differences in local abiotic conditions, invader abundance, and traits and composition of the native community. One way to improve predictive ability about the impact of an invasive species given variable conditions is to exploit known mechanisms driving invasive species’ success. Invasive plants frequently exhibit allelopathic traits, which can be directly toxic to plants or indirectly impact them via disruption of root symbionts, including mycorrhizal fungi. The indirect mechanism – mutualism disruption – is predicted to impact plants that rely on mycorrhizas but not affect non-mycorrhizal plant species. To assess whether invader-driven mutualism disruption explains observed changes in native plant communities, we analyzed long-term (1998–2018) plant cover data from forest plots across the state of Illinois. We evaluated native plant communities experiencing a range of a..., These data were collected by the Illinois Critical Trends Assessment Program (CTAP) of the Illinois Natural History Survey (Carroll et al. 2002). This program was established to quantify the conditions and ecological trends of three terrestrial plant habitat types (forests, wetlands, grasslands) in Illinois. We used plant survey data from the CTAP forest ground cover sites collected from 1998 to 2018. Sites were resampled on a 5-year rotation, meaning that ~1/5 of the plots were surveyed each year. If a site no longer met the CTAP criteria for inclusion in the monitoring program when resurveyed, a new, unassociated site elsewhere in the township was established to replace it. Because many plots are located on private land, latitude and longitude were rounded to 2 decimal points for privacy. Original dataset available by request from https://publish.illinois.edu/ctap/inhs/.
We used the species-specific ground cover data (<1m in height) for this study. At each site, ground cover sampli...,