Conservation and Restoration of Piedmont Prairies
Native savannas and grasslands were once widespread in the Piedmont of the eastern Unites States. Most of these habitats have vanished as a result of fire suppression, extirpation of bison, invasion by non-native pasture grasses, and urban development. At the Clifton Institute we are studying remnant grasslands in the Piedmont of northern Virginia to (1) better understand what plants and animals are found in these habitats, (2) learn about the conservation status of these species and sites, and (3) come up with strategies to restore Piedmont prairies.
The Composition and Conservation Status of Piedmont Prairies in Northern Virginia
In the summer of 2020, we teamed up with researchers from the Restoration Ecology Lab at Virginia Tech to study remnant grasslands at 38 sites in five counties. We found nearly 500 species of plants, including several rare or threatened species such as Torrey’s Mountain-mint (Pycnanthemum torreyi), Stiff Goldenrod (Solidago rigida), and Yellow Nodding Ladies’ Tresses Orchid (Spiranthes ochroleuca). Amazingly, one of our 50-by-2-meter plots had 93 species of plants, which made it the third most diverse vegetation plot that has been sampled in the state (out of 4,500 surveys). We also found that most of the high quality grasslands we encountered were in power line clearings (as opposed to pastures, hay fields, or fallow fields) and that diverse prairies were found on a wide range of soil types. Finally several of the diverse prairies we studied are threatened by invasive plants or urban development, and we are working with landowners and power companies to conserve these sites. We aim to publish these results in 2022. This research was funded by the Virginia Native Plant Society.
We discovered this diverse, high quality, Piedmont prairie remnant in a Prince William County power line clearing during our research in 2020. We found 93 species of plants in a 50×2-meter plot here, which makes this one of the most diverse vegetation communities in the state of Virginia.
Experimental Restoration of Piedmont Prairies for the Benefit of Plants, Insects, and Birds
In 2019 we started a major project to restore 110 acres of overgrazed cattle pasture to a native grassland. The first step in establishing a native grassland is getting rid of the nonnative plant species; we did this by using herbicides and repeated discing (an organic alternative similar to plowing). Once native plants are established, we will maintain the grassland by mowing or prescribed burning. We are testing eight combinations of establishment and management methods in order to figure out how best to help declining native species. The map below shows the layout of our experiment. Virginia Working Landscapes and the Oak Spring Garden Foundation are replicating this experiment on their respective properties. The restoration work is being funded by the Natural Resources Conservation Service, the Oak Spring Garden Foundation, and the Raines Family Fund.
We are measuring the effectiveness of each treatment with biodiversity and soil surveys. To get a baseline understanding of the state of the pasture, volunteers from the Piedmont Chapter of the Virginia Native Plant Society estimated the relative abundance of all plant species in the pasture over the course of the summer of 2018 (you can find the full list here). Starting in the summer of 2018, Clifton Institute staff, collaborators, and volunteers have conducted regular bird, butterfly, and plant surveys, all of which will continue in the years to come. Jordan Coscia, a Ph.D. student in the Restoration Ecology Lab at Virginia Tech, is measuring the effectiveness of each experimental treatment in terms of restoring native plants as part of her dissertation. Our findings will be used to guide our future restoration projects and to educate local landowners.
This is a map of our 110-acre grassland restoration experiment. We are comparing the effectiveness of eight treatments (control, herbicide, organic, fire, and mowing) to convert the field from non-native to native plants, and to benefit declining insects and birds.