Grasslands: Savanna Base Layer In terms of acreage, the restored native grasslands comprise the largest vegetation change proposed. It involves the conversion of some 125 acres of cool season fescue grasses, orchard grass, and other exotics (as well as some natives – see the summary of Virginia Working Landscapes inventory work in Part 2 for a list of existing species in grasslands) into native warm season grasses and wildflowers (NWSG). With the addition of scattered trees, a savanna landscape will be created. There are three primary variables to installing a NWSG meadow. Each is a moving target with a variety of options, and mixed published opinion. A final decision on each is dependent on budget tolerance, level of patience, and desired outcome. COMPOSITION Although savannas and large grasslands occurred in the Piedmont and other areas of the Shenandoah Valley in presettlement times (see Part 1), there is no clear agreement of what the community was composed of, nor the relative abundance of species. Virginia DCR (Fleming et al. 2017) lists a Piedmont Prairie natural community, noting, however, its unclear history. Vast areas of oak-savanna in the upper Midwest, occurred in historic times and ecologists have better information for those
ecosystems. But on account of its early settlement history, Virginia lacks solid documentation of those community types. This is both freeing, and also presents challenges. It’s freeing because there is no right or wrong list when it comes to species composition for NWSG. The challenge lies in trying to be true to Virginia’s natural communities and deciding which species to include. There are many resources available with suggested lists. The list provided here suggests the most common species that make up the vast majority of biomass in the community. It is an average of many lists. PROCESS Most sources suggest broad-spectrum herbicide is the most efficient and effective means for eliminating exotic cool season grasses. Considering the slopes at Oak Spring, disking and tilling will leave soils vulnerable to erosion. With proper herbicide treatment and use of a no-till drill, soil can be maintained. Sources agree on the importance of using the correct seed drill. The depth to which the seeds are planted is critical. Seeds of bluestem, Indian grass and others are light and fluffy and need to be set at a specific depth. A proper seed drill cuts through the layers of dead fescue, then plants a seed at the correct depth, and seals the trough over. Seed drills are available for use from Virginia Working Landscapes and VA Division of Forestry.
180