Our research on sugar maple decline on the Allegheny Plateau and across northeastern North America has heightened our attention to the distribution of nutrients across the landscape and its relation to glaciation, landscape position, and atmospheric deposition. It has also increased our appreciation of the differences in nutrient requirements among plant species, and how these nutrient requirements can increase or decrease the resilience of forests to stressors such as defoliation and drought. We plan to strengthen our understanding of the relationships among nutrients, landscapes, glacial history, Allegheny Plateau plant species, and forest health, and to develop guidelines to assist managers in integrating this understanding into management strategies. This work will continue to focus primarily on sugar maple, and include development of both maps and indicator plant associations to aid managers in sustaining Northern Hardwood forests. As resources permit, we will add other species to this work. Research on this problem will lead to the development of guidelines and support management unit-level indicators for Montreal Process Criteria 1 (biological diversity), 2 (productive capacity of forest ecosystems), 3 (maintenance of forest health and vitality) and 6 (long-term socio-economic benefits to meet the needs of societies). We will study the effects of stress and nutrient relationships on sugar maple regeneration. Regeneration of sugar maple appears to be limited by site, seed supply, insects, and diseases. We will increase our efforts to understand the relationships among soil parent material, soil processes, nutrient cycles, native and exotic insects and diseases, and regeneration of sugar maple. This work will depend on results from our long-term study of the effects of liming, herbicide, and deer exclusion on sugar maple dominated forests, and is closely related to our forest renewal problem. Our primary partners in this work include USFS Research Work Unit NE-4558 (Delaware, OH) and the Pennsylvania DCNR Bureau of Forestry. This research will be conducted at the research plot and stand scale, although landscape influences will be among the factors considered. We will increase our understanding of site/species relationships. Using data from existing long-term studies, we will develop a DRIS (diagnostic recommendations and treatment) system for sugar maple, reflecting its need for soils with at least threshold levels of base cations including magnesium and calcium. We will link these requirements with productivity of sugar maple on sites of different soil nutrient status. We will also develop maps and systems of indicator plants to help managers recognize the underlying site conditions where they are working in ways that are easily adapted for field use. As resources permit, we will adopt this approach with other species, including black cherry, for which we have considerable preliminary data. Our primary partners in this work include USFS Research Work Units NE-4558 (Delaware, OH), NE-4352 and NE-4155 (Durham, NH), the Pennsylvania DCNR Bureau of Forestry, the Allegheny National Forest, and the NY Department of Environmental Conservation. This is intrinsically landscape scale research. As resources permit, we will conduct research to understand the mechanisms that influence the health of sugar maple. This work will build on our ongoing study of the effects of soil liming on declining sugar maple on the Susquehannock State Forest, and our study of sugar maple decline along a topographic gradient across the northeastern US. In these studies, sugar maple decline occurred after at least two moderate to severe defoliations within a decade on sites with low base cation status. Both poor nutrient status and defoliation were required for sugar maple decline to develop. These results have been described as the best empirical evidence of the decline-disease hypothesis advanced by Mannion and Huston and others. The scientific team conducting this research will seek grant funding for a manipulative study to confirm the relationships observed in the observational studies. Primary partners in this research will be USFS Research Work Units NE-4558 (Delaware, OH), NE-4352 and NE-4155 (Durham, NH), NE-4505 (Hamden, CT), the Pennsylvania DCNR Bureau of Forestry, and the NY Department of Environmental Conservation. Although we will conduct manipulative work under this problem at the research plot or stand level, position within the landscape will be a critical characteristic of study sites.