SURFACE SOIL PROPERTY CHANGES IN ALDER BALD WITH RESPECT TO GRASSY BALD AND RHODODENDRON BALD VEGETATION ON ROAN MOUNTAIN, TENNESSEE/NORTH CAROLINA

The Grassy Balds of Roan Mountain Tennessee/North Carolina are classified as temperate mountain balds and ranked as a G1 Biome, the highest-level of rarity among ecosystems in the world. The balds are part of the Blue Ridge Physiographic Province, with underlying Cambrian and Precambrian rocks: Roan gneiss, Cranberry granite, and Bakersville gabbro. This area is home to a rare disjunct population of Green Alder (Alnus viridis ssp. crispa). A major problem currently facing this and other rare species on the balds is woody plant encroachment. Over the last century, around 75% of the grasslands have been lost, with the majority of the losses occurring in the last 50 years. Apart from the rare ecosystems, which house many rare species, Roan Mountain deserves a high level of conservation for the beautiful mountain vistas observed by the thousands of visitors who voyage from around the country. This interdisciplinary study was conducted, in part, to gain an understanding of the vegetation’s impact on the soils of the area. We designated three vegetation communities for study: Southern Appalachian Alder Bald (dominated by Green Alder), Rhododendron Bald (dominated by Rhododendron catawbiense), and Grassy Bald (dominated by mixed grasses and sedges). The specific aim of this study was to compare physical and chemical surface soil properties of the different vegetation communities. The soils in these communities exhibited sandy loam to loamy texture. Our field studies indicated Green Alder grows in very thin and well-drained soil cover. In contrast, the grassland and Rhododendron community have thicker soil cover with larger proportion of clays, and can retain more moisture than that of Green Alder. The soil under Alder and Rhododendron vegetation is darker because of high production of nutrient rich leaf litter. The soil pH is expected to vary with vegetation community type. A high level of nitrogen is expected in the Green Alder community since this plant is a known nitrogen fixer. This study allows a more complete understanding of the distribution of nitrogen and pH balance in the Grassy Balds of Roan Mountain.