1. Introduction Acid deposition (AD) from air pollution is a chronic stress on forest ecosystems in the northeast and mid-Atlantic regions of the U. S. The health of some high elevation forest streams has declined and forest soils have become less fertile and more acidic. However, it is unclear if and how the rest of the forest ecosystem has been affected, and if management plans of National Forests in this region need to accommodate this potential threat to forest health. Data from Forest Inventory and Analysis (FIA) plots are being used to determine if any measurable forest health declines attributable to AD are occurring on the Monongahela National Forest. Hypothesis 1.Forest sensitivity to AD can be estimated using site factors that influence soil buffering and forest productivity. 2.A sensitivity gradient can be tested using Basal Area growth as an indicator of productivity on FIA sites. 3.Site sensitivity will be a factor of: Parent material Soil depth Soil mineralogy Aspect Elevation Landform 4.Soil and foliage sampling can provide ground- based evaluations of site sensitivity to AD. 5.Current FIA protocols may need to be adjusted to adequately monitor AD effects. Implications The Monongahela National Forest, in eastern West Virginia, lies within 300 kilometers of seven of the highest 10 SO 2 emitting coal-fired power plants which makes it subject to high levels of AD (Figure 2). National Forests are mandated to manage for multiple uses such as wildlife protection, water and air quality, and timber production. Because AD may threaten many of these resources it is critical to understand how this source of pollution affects forest ecosystem services. The results of this project will be used to develop monitoring and management protocols for the forest. Acknowledgements The USDA Forest Service Timber and Watershed Lab and the Monongahela National Forest have provided funding for this project. Many thanks to a number of Forest Service employees who helped develop the MOU for FIA data access. We also thank the Forest Service employees and Virginia Tech students who helped with field sampling. We are grateful to our partners at NRCS and the Forest Service FHM administrative office Works Cited National Atmospheric Deposition Program (NRSP-3), 2006. Acid Deposition Effects on Forest Composition and Productivity in the Monongahela National Forest P.E. Elias 1, J.A. Burger 1, M.B. Adams 2, and S. Connolloy 3 1 Virginia Tech Department of Forestry, Blacksburg, VA 2 USDA Forest Service Timber and Watershed Lab, Parsons, WV, 3 USDA Forest Service Monongahela National Forest, Elkins, WV Methods Calculate growth on Forest Inventory and Analysis (FIA) Plots on the Monongahela National Forest from 1987-2005 (Figure 1) Map growth over the hypothesized factors that influence site sensitivity to acid deposition Correlate this mapping exercise with field-based soils data taken adjacent to 30 FIA plots Soils at the 30 plots will be sampled using the Forest Health Monitoring protocol, and one specifically tailored for measuring AD effects on soils. The data from both sampling approaches will be correlated with changes in productivity and composition. At 10 sites sample foliage from indicator species Correlate foliar chemistry with changes in productivity and composition to test its ability to monitor AD effects Progress to Date Basal area increment has been calculated for 95 plots on the Monongahela National Forest; rates ranged from 0 - 8 ft 2 /ac/year. This growth has been mapped over the hypothesized site sensitivity gradient, and correlation statistics are being run. Soils adjacent to 10 FIA plots have been sampled by depth and by horizon. At 10 additional sites foliage has been sampled from indicator species, including L. tulipifera, Q. rubra, P. serotina, C. ovata and A. saccharinum.. Figure 2: pH of precipitation in the Southeastern United States (NADP, 2006) The Monongahela National Forest Figure 1: FIA Locations across the Monongahela National Forest Example of forest soil profile. Study Area