Management effects on erosion of Civil War military earthworks

ABSTRACT:

The U.S. National Park Service has the difficult task of preserving Civil War battlefields, including trench and fortification earthworks, while allowing public access. Soil erosion, both natural and human-induced, is a primary concern facing the preservation of the military earthworks. Vegetative cover is central to protecting military earthworks against erosion and a variety of vegetative-management regimes have evolved in the parks. This study used a modification of the Universal Soil Loss Equation (Dissmeyer and Foster, 1984) and erosion pins to estimate soil erosion that occurred for five earthwork-vegetation management practices: prescribed burning, mowing, herbaceous-trimming, woody-trimming, and forest for one year following treatment installation.

Both erosion estimation methods indicated that the prescribed burning treatment resulted in the highest erosion rates. The erosion pin data indicated that the woody-trimming treatment could potentially increase erosion. The forested military earthworks had the lowest erosion rates, while the trimmed and mowed management regimes had intermediate erosion values. Overall, this study indicates that military earthworks managed for continuous ground cover with minimum physical intervention are best protected from erosion. Treatments that minimize ground cover should be used only in areas where historic accuracy regarding vegetation or high visitor interest can justify the potential for increased erosion.