IMPACTS OF LAND-USE HISTORY, FIRE, DEER BROWSING AND GLOBAL CHANGE ON FOREST STRUCTURE AND FUNCTION IN THE EASTERN UNITED STATES.

One of the most fundamental approaches for evaluating the disturbance history of a stand is through the tree-ring science of dendrochronology. Calculation of releases is a powerful and unique tool in that it reflects both localized and stand-wide disturbances at a high temporal resolution. Mean fire intervals of 4-20 years have been reported for most oak forests in the eastern and central U.S. Oak species possess a suite of adaptations for fire and drought stress, but not for competing in a closed forest understory dominated by later successional species. Strong indirect evidence for this idea is found in the fact that when fire is suppressed in oak forests during the 20th century, they are rapidly invaded by later successional, fire sensitive species, such as maple, beech, birch, and blackgum. These species are now replacing oak and becoming dominant trees. We believe that the suppression of fire and the successional replacement of oak forests is a cause and effect relationship. Throughout the eastern U.S., interactions and feedback among climate, vegetation, soils and topography, large- and small-scale disturbances, anthropogenic factors, and wildlife impacts created an ecological dynamic for oak forests that can only be understood from a long-term, multifactor perspective. By studying the natural and cultural environment under which oak forests developed we may better understand the ecological requirements needed to manage and conserve our existing oak and pine communities.