H13L-1750
Acidic Deposition along the Appalachian Trail Corridor and its Effects on Acid-Sensitive Terrestrial and Aquatic Resources
Monday, 14 December 2015
Poster Hall (Moscone South)
Gregory Brad Lawrence1, Timothy J Sullivan2, Douglas A Burns3, Scott W Bailey4, Bernard J Cosby Jr5, Martin Dovčiak6, Holly A Ewing7, Todd C McDonnell2, Rachel Riemann8, Juliana Quant6, Karen C Rice9, Jason Siemion10 and Kathleen C Weathers11, (1)USGS New York Water Science Center Troy, Troy, NY, United States, (2)E&S Environmental Chemistry, Corvallis, OR, United States, (3)USGS, Troy, NY, United States, (4)US Forest Service Durham, Durham, NH, United States, (5)Center for Ecology and Hydrology Bangor, Bangor, United Kingdom, (6)SUNY College of Environmental Science and Forestry, Environmental and Forest Biology, Syracuse, NY, United States, (7)Bates College, Lewiston, ME, United States, (8)USDA Forest Service, Troy, NY, United States, (9)University of Virginia Main Campus, Charlottesville, VA, United States, (10)US Geological Survey, Troy, NY, United States, (11)Cary Institute of Ecosystem St, Millbrook, NY, United States
Abstract:
The Appalachian National Scenic Trail (AT) spans 3,500 km from Georgia to Maine. Over its length, the trail passes through a corridor with wide variations in climate, bedrock type, soils, and stream water quality. These factors create a diverse range of ecosystems. The health of these ecosystems is a cause for concern because the AT passes through the heavily populated eastern U.S. with its many sources of sulfur (S) and nitrogen (N) emissions that produce acidic deposition. To address concerns about the health of the AT, a study was designed to evaluate the condition and sensitivity of the AT corridor with respect to acidic deposition. Collections of stream water (265 sites), soil (60 sites), tree cores (15 sites) and atmospheric deposition samples (4 sites) were made along with understory and overstory vegetation measurements (30 sites) over the full trail length within a 40 km-wide corridor. Existing data on atmospheric deposition, geology, vegetation, stream chemistry, and soil chemistry were also used in the analysis. Mean acid-neutralizing capacity (ANC) was lowest in the streams in the North section, intermediate in the Central section and highest the South section, despite the South having the highest acid rain levels. At least 40% of the study streams exhibited pH and/or Ali measurements that indicated potential harm to biota. Approximately 70% of the soil sites had values of base saturation under 20%, the threshold below which acidic deposition can mobilize inorganic aluminum (Ali), the form harmful to terrestrial and aquatic life. Compositional similarity of understory and canopy species was positively correlated with acidic deposition, suggesting that during past decades, species poorly adapted to acidic deposition were replaced with tolerant species. Target loads modeling indicated that exceedance of sulfur target loads to achieve stream ANC = 50 µeq/L by the year 2100occurred throughout the trail corridor.
