Twenty years of tallgrass prairie restoration in northern Illinois, USA

Elizabeth Bach and Bill Kleiman share their latest findings from monitoring long-term ecosystem restoration on The Nature Conservancy’s Nachusa Grassland preserve.

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 published in Ecological Solutions and Evidence, as part of the cross-society special feature on the UN Decade on Ecosystem 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.

A diverse native plant community at The Nature Conservancy’s Nachusa Grasslands in northern Illinois © Dee Hudson

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 from the exact same transect locations, exclusively focusing on plant community changes over time.

VegSurveys_NickFoster_ElizabethBach_MG_0656-©Dee Hudson
Nick Foster (left) and Elizabeth Bach (right) collect plant community data along a transect at Nachusa Grasslands © Dee Hudson

The results show that 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 natives. Savanna habitats have transitioned from shrub-dense communities to open understories dominated with native herbaceous plants.

Our long-term results appear to contrast previous studies that have observed declines in plant diversity over time within tallgrass prairie restorations. However few restorations have been repeatedly monitored for long periods, so previous work had 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 from one or two seasons of field work – but it can limit our ability to untangle plant community changes over time, from changes in restoration practices over time.

Generally, our data show that long-term restoration efforts at Nachusa Grasslands have successfully reached their floristic goals.

Transect collage
Prairie restoration transects pictured in 1996, the first year of data collection © Bill Kleiman

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.

Therefore 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 are continuing our long-term monitoring of plant and animal communities to evaluate how our efforts succeed and how they fall-short and look forward to continuing to learn from our work and the work of colleagues engaged in restoration around the world.

Read the full article: “Twenty years of tallgrass prairie restoration in northern Illinois, USA” in Issue 2:4 of Ecological Solutions and Evidence.

Discover more articles from our cross-society, cross-journal Special Feature on the UN Decade on Ecosystem Restoration.

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