The problem with buckthorn
Common buckthorn (Rhamnus cathartica) is one of Minnesota's most notorious invasive plant species. Originally introduced in the 1800's as an ornamental plant for hedge rows, buckthorn has now invaded forests throughout the state and can be found in almost every county. Buckthorn devastates native ecosystems as it shades out native plant species and reduces habitat quality for wildlife. Minnesotans are working hard to remove buckthorn, but keeping buckthorn out for good is an ongoing challenge. After its initial removal, buckthorn quickly returns through resprouting from cut stumps and from seeds in the soil.
What we know
The Cover It Up! research project investigates if re-establishing native plants can control buckthorn following removal efforts. Through a combination of field experiments, we have been able to determine the limits of buckthorn shade tolerance and identify key levels of shading that result in native species excluding buckthorn. In particular, we've shown woody species to be capable of producing this level of shading under some circumstances, but if, when, and where seed mixtures can result in these critical level of shading is still unclear. To better understand the potential value of seeding we are working with Citizen Scientists to expand the study throughout the state.
What Citizen Scientists are doing
The Citizen Science project works with volunteers throughout the state who conduct ecological research and contribute to more sustainable buckthorn control. Participants include landowners with buckthorn on their property, public or private land managers, non-profit groups, schools, community or friend groups, faith groups and many others.
The project is expected to run through summer 2022 and focuses on forested and woodland areas throughout the state where buckthorn is present. Participants removed buckthorn from areas (measuring ~ 30 x 40 ft) to establish experimental sites. Within each site, six squares (measuring 5 x 5 ft) were demarcated, and half of those squares were seeded with a mix of native grasses, sedges, wildflowers, shrubs and trees. Each summer between 2020-2022, participants report observations back to the program. Training and materials needed for the experiment are provided at no cost to participants by the University of Minnesota. More information about project commitments and activities are here.