by Elizabeth Bach, Research Scientist at Nachusa Grasslands

This blog originally appeared in The Applied Ecologist blog on Dec. 7, 2021.

The challenges facing our planet can feel overwhelming and paralyzing. Climate is changing, biodiversity is declining, people are struggling to be in community with one another. However, there are signs of hope. The United Nations declared 2021-2030 as the Decade on Restoration, upholding ecosystem restoration as a transformative approach to addressing environmental challenges. To understand, improve, and enact restoration practices, it is important to monitor restoration outcomes.

Our new article Twenty years of tallgrass prairie restoration in northern Illinois, USA published in Ecological Solutions and Evidence, as part of the cross-society special feature on the UN Decade on Restoration, provides one example of long-term ecosystem restoration monitoring. This dataset follows plant communities in native prairies, savannas, and planted prairies at The Nature Conservancy’s Nachusa Grasslands preserve. Conservation and restoration efforts began at Nachusa in 1986. Volunteers and staff began right away to remove invasive species, restore historic fire regimes, and plant tallgrass prairie restorations into crop fields. As the vision grew, project manager Bill Kleiman knew measuring restoration outcomes would be vital to honing restoration approaches and building support for large-scale restoration. He established several permanent transects in the mid-1990s, recording plant communities on native prairies, planted prairies, and savanna habitat at the preserve. Amidst the many demands of the project, Bill ensured these transects were resampled several times across the years as the preserve expanded.

Our paper synthesizes the data collected between 1994 and 2016. Plant communities on native prairies have maintained their unique structure, including most of the rare plants that initially attracted the attention of conservationists. Plant communities on native prairies have maintained their unique structure, including most of the rare plants that initially attracted the attention of conservationists.

Planted prairies reached 75-80% native plant species, achieving restoration goals of establishing plant communities dominated with native species. Savanna habitats have transitioned from shrub-dense communities to open understories dominated with native herbaceous plants.

Our long-term results contrast previous studies that have observed declines in plant diversity over time within tallgrass prairie restorations. Few restorations have been monitored repeatedly over time, so previous work has relied on sampling prairies of various ages to infer changes over time. This approach has many advantages, including being able to perceive long-term trends in one or two seasons of field work. However, it can limit our ability to untangle plant community changes over time from changes in restoration practices over time. At Nachusa, as in many places, our most recent plantings included more diverse seeding mixes and denser seeding rates. These younger restorations do have greater plant diversity than older restorations. In this study, we synthesized long-term data from the exact same transect locations, exclusively focusing on plant community changes over time.

Generally, these data show that long-term restoration efforts at Nachusa Grasslands have successfully reached floristic goals. Active management is central to our approach to restoration. The tallgrass prairie ecosystem developed over millennia with Indigenous people actively dwelling with the system. Numerous Indigenous cultures cultivated fields, planted trees, set fires to select plant communities and attract large game like bison, and harvested food, fiber, and shelter from the landscape. Their actions have been essential to shaping and sustaining this ecosystem. It is hardly surprising the plant communities at Nachusa have responded neutrally or positively to regular prescribe fire, aggressive invasive species removal, and active planting into former crop fields and degraded areas.

Today, Nachusa Grasslands is 1600 ha, ten times the size of the original area. Volunteers, staff, and scientists work side by side actively restoring the landscape. Many animals are also rebounding. Restoration efforts are recreating a medium landscape-scale habitat, large enough to support organisms ranging from tiny insects to the iconic bison. We continue long-term monitoring of plant and animal communities to evaluate how our efforts succeed and how they fall-short. We look forward to continuing to learn from our work and the work of colleagues engaged in restoration around the world.