VULNERABILITY OF MID-ATLANTIC FORESTED WATERSHEDS TO TIMBER HARVEST DISTURBANCE REX H. SCHABERG 1 * and ROBERT C. ABT 2 1 Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC 27708; 2 Department of Forestry, North Carolina State University, Box 8008, Raleigh, NC 27695 USA (* author for correspondence, phone: 919-515-7790, fax: 919-515-8149, e-mail: rex_schaberg@ncsu.edu) Abstract. Forested watersheds of the Mid-Atlantic Region are an important economic resource. They are also critical for maintaining water quality, sustaining important ecological services, and providing habitat to many animal and plant species of conservation concern. These forests are vulnerable to disturbance and fragmentation from changing patterns of land use in the Mid-Atlantic Region, and from harvests of commercially mature and relatively inexpensive timber. The U.S. Department of Agriculture Forest Service (USDA-FS) Forest Inventory and Analysis (FIA) compiles data on forest condition by state and county. We have transformed these FIA data to a U.S. Geological Survey (USGS) 6-digit hydrologic unit code (HUC 6) watershed base, and projected trends in timber growth, inventory, and harvest to 2025 using a timber economics forecasting model (SRTS). We consider forest sustainability from the perspective of timber production, and from the perspective of landscape stability important to conservation values. Simulation data is combined with FIA planted pine acreage data to form a more complete picture of forest extent, composition, and silvicultural practice. Early recognition of prevailing economic trends which encourage the fragmentation of mature forests due to increasing timber harvests may provide managers and policy makers with a planning tool to mitigate undesirable impacts. Keywords: environmental modeling, forest landscape modeling, regional vulnerability assessment, simulation model, timber harvest, watershed, Mid-Atlantic 1. Introduction The forested watersheds of the Mid-Atlantic provide an array of resources to the human, plant, and animal populations of the East Coast region of the United States. These watersheds help sustain water quality for the growing human population; they provide a host of recreational opportunities; and they provide timber which constitutes an important economic resource for the region. Additionally, forested watersheds provide significant and, in some instances, potentially vital habitat to plant and animal species of conservation concern. With 77.8 million acres of privately owned forest in 1982, forests represent the dominant land use in an eight state Mid- Atlantic Region including Delaware, Maryland, New Jersey, New York, North Carolina, Pennsylvania, Virginia, and West Virginia. These states contain an additional 7.2 million acres of federal land, much of which is forested (USDA NRCS, 2000). Environmental Monitoring and Assessment 94: 101–113, 2004. c 2004 Kluwer Academic Publishers. Printed in the Netherlands.