Forest ecosystems, restoration ecology, fire ecology, and community ecology. Investigate vegetation dynamics (mortality, regeneration, composition, and diversity changes) of forest species following forest disturbances (cutting, burning, windthrow, and insects and pathogens); and (2) assess variation in vegetation dynamics across environmental gradients, feedback linkages between vegetation dynamics and ecosystem processes, and responses to stressors and other disturbances. Current and future research emphasizes the effects of multiple disturbances on vegetation dynamics and relates these dynamics to ecosystem processes such as net primary production and water, nutrient and carbon cycling in southern Appalachian forest communities.
Riparian area structure and function; Rhododendron maximum in riparian areas; loss of eastern hemlock; and restoration of riparian areas. The role of a diverse herbaceous flora in ecosystem function.
importance of research
In many regions, riparian areas contribute significantly to plant diversity in a watershed by providing unique habitat. Near-stream vegetation operates synergistically with geology, soils and topography to influence channel form, in-stream habitat, nutrient dynamics, and temperature and flow patterns. The diversity and productivity of riparian communities are strongly linked to the condition of the landscape, and maintaining some level of protection to streamside vegetation is believed to be integral to preserving the biological integrity of steam ecosystems. Knowledge of the functional role of diversity is important for evaluating how changes in vegetation diversity impact ecosystem processes such as net primary production and nutrient and water cycling. The experimental removal of a species or a functional group of species from an ecosystem can provide information on their contribution to ecosystem function.
Nutrient Cycling Modeling using NUCM: Predicting future response to altered atmospheric environmental conditions requires a modeling approach because of the complexities of nutrient cycling processes in forest ecosystems. Southwestern pine ecosystems. Regeneration of ponderosa pine is a problem for resource managers in the Southwest because of the increased frequency of large wildfires. Part of the regeneration problem is attributable to competition for water from grasses sown on the burned sites. I investigated how different herbaceous species affect survival and growth of ponderosa pine seedlings and whether various herbaceous species had different effects on pine seedling water potential, soil moisture, and soil nitrogen. Competitive effects of northern hardwoods on planted red pine growth, nutrient use efficiency, and leaf morphology. On sites previously occupied by northern hardwoods in the northeastern U.S., large industrial landowners often plant conifers after clearcutting because these species are preferred for pulp and paper products. I examined the competitive effects of three northern hardwood species on planted red pine seedlings.