Floristics, Conservation, and Restoration of Virginia's Piedmont Grasslands

Abstract

The native grasslands of Southeastern North America contain higher native plant diver- sity than the prairies of the Great Plains, but they have lost 90-99% of their historic range through disruption of their natural disturbance regimes and conversion to agricultural lands. To inform the conservation and restoration of Southeastern grasslands in Virginia's Pied- mont, I address four research objectives: 1) Characterize the floristic composition of native grasslands; 2) Assess the impacts of agricultural land use and restoration on grassland bio- diversity; 3) Determine the barriers to grassland regeneration through the comparison of restoration techniques; and 4) evaluate the impacts of long-term land management on native grassland plant communities. I identified 604 native plant taxa across 132 native grass- lands in Northern and Central Virginia. Only 57% of these taxa were found in agricultural, post-agricultural, and restored grasslands. Experimental restorations had 52% higher native species richness than agricultural grasslands, but only 49% of the native richness of refer- ence grasslands. Native richness and cover did not differ between treatments, indicating that native grassland regeneration is limited by post-agricultural legacy effects. Finally, an evalu- ation of 30 years of management in Shenandoah National Park revealed that longer intervals between prescribed burns were associated with increases in woody plants and decreases in forbs, indicating that frequent management is necessary to maintain open conditions. To- gether, these results reveal that grassland management and restoration strategies employed in northern and central Virginia are insufficient to support native biodiversity, demonstrating the critical conservation value of the remaining native grasslands.