Dendroecology of Old-growth Forests
A number of undisturbed, old-growth oak and pine forests in the mid-Atlantic have been located and used for detailed analysis of composition, structure, historical development, disturbance history, species recruitment patterns, and future succession. Dominant forest types were for study include white pine, pitch pine, white oak, chestnut oak, and red oak. Prior to European settlement, oak and pine species grew in uneven-aged conditions and experienced recurring understory burning. Fire exclusion during the 20th century appears to be leading to the successional replacement of most oak and pine forest to later successional species, in particular red maple, sugar maple, beech, and blackgum.
Ecophysiological Responses to Interaction Among Light, Site, and Drought
Naturally occurring field plants are invariably affected by multiple environmental interactions, including concurrent stress factors. Seasonal physiology and leaf morphology were monitored in naturally occurring tree species under a variety of ecological conditions in the eastern United States, including high- and low-light environments, burned and unburned plots, and sites of contrasting water relations. In most cases seasonal droughts allowed us to evaluate the impact of multiple stresses or environmental interactions in ecologically contrasting tree species. The results of these studies indicate the wide variation and complexity of responses to environmental interactions in temperate tree species.
Vegetation Classification of Mid-Atlantic Forest Types
The mid-Atlantic region is highly diverse physiographically. This variation produces highly distinct forest types on different physical units. Studies of vegetation classification have been completed for a large number of second-growth hardwood- and conifer-dominated forests in central Pennsylvania, West Virginia, and Virginia. These studies have been successful in relating spatial variation in forest composition and structure to physiographic variation. Temporal variation in these forests has been related to land-use history. Studies of presettlement forest in each region through the use of witness tree data indicate the dramatic changes that have occurred since European settlement.