COS 182-5 - Restoration method and fire management as drivers of restoration outcomes in tallgrass prairie

Background/Question/Methods

Land-use intensification has resulted in a vast reduction of tallgrass prairie and has had detrimental effects on biodiversity. Habitat restoration is critical for preventing the continued loss of plant diversity. Despite international efforts to restore ecosystems, monitoring the success of restorations is rare and their outcomes remain uncertain. Consequently, the mechanisms responsible for successful restoration are poorly understood. Here we look at historical land-use legacies, restoration method, and fire management as three mechanisms known to affect outcomes in restored communities and work to disentangle their relative importance. In 2018 and 2019, we conducted intensive vegetation sampling at 36 restored tallgrass prairies throughout southern Wisconsin that are enrolled in the National Resource Conservation Service’s (NRCS) Agricultural Conservation Easement Program (ACEP) Wetland Reserve Easements (WRE). Detailed documentation of the restoration method and fire history were obtained from the NRCS and sites were split into three categories: 1) not seeded, 2) seeded and 3) seeded and burned. Additionally, soil samples were collected for in-depth nutrient analysis. With these data we ask the following questions: 1) How does restoration method affect the different metrics of restoration success in tallgrass prairie? 2) Does fire management interact with the restoration methods to influence success?

Results/Conclusions

We found a wide range of restoration outcomes across our study sites, both within and between site categories. For example, species richness varies from 19 species per site to 111 species per site within the same restoration category. Our data suggests that both restoration method and fire impact restoration outcomes. Different metrics of success (e.g. % seeding establishment, species richness, native species richness, and coefficient of conservatism) respond differently to restoration method and management. Overall species richness is not affected by restoration category, however, the quality of the vegetation (i.e. coefficient of conservatism scores and native richness) improves with seeding and fire management. Elevated soil nutrients resulting from historical land-use can have effects on vegetation for decades and may be a major driver of within site category variation. Other factors that may influence the outcome of a restoration include restoration size, fire frequency, time since last burn, or proximity to a high quality prairie. Overall, the results suggest that the restorations are improving plant community composition, which should provide more resources for pollinators and wildlife.