Scaling forested ecosystem processes under disturbance regimes and forest management: Case study of Southeast
A wide array of human-induced disturbances can alter the structure and function of forests, including climate change and management. While forest management (production, ecological, passive, preservation) is one of the most intensive land use changes that occur across the Southeastern U.S., interactions among management, changing climate and natural disturbance are not well characterized. Projections of the range of plausible responses of changes in structure and function of forests and the services they provide to climate change and management are need for informed decision making on new management approaches under changing climate, as well as adaptation strategies for coming decades. Terrestrial biosphere models (TBMs) provide an excellent opportunity to assess simultaneous responses of terrestrial ecosystems to climatic perturbations and management across multiple spatio-temporal scales, but management has rarely been incorporated in these models and when it is, it relies on stand scale assumptions not evaluated at regional scales. We incorporated common forest management practices into the Ecosystem Demography model 2 (ED2). Since ED2 incorporates non-linear effects of fine-scale (~10-1 km) heterogeneity in ecosystem structure both horizontally and vertically at a plant level, it is an ideal candidate to incorporate different forest management practices across various spatial scales.
We implemented six forest management practices in ED2: clear-cut, planting, partial harvest, restoration, salvage, and herbicide. Results were validated against observed data across four different sites in the U.S. Southeast (Duke Forest, Joseph Jones Ecological Research Center, North Carolina Loblolly Pine, and Ordway-Swisher Biological Station). Then using remote sensing land-cover information, we selected 4000 stratified random samples of 10x10 km2, covering predominant management types, to evaluate regional impacts of forest management and natural disturbances on forest ecosystems. Results indicate that forest management is the strongest driver of forest structural change compared to climate and edaphic conditions. Moreover, indirect effects of climate change through impacts on disturbance regimes are more important for forest ecosystems function and structure than the direct effects of climate change on temperature and precipitation. Therefore, adaptation policies that affect forest management have more profound impacts than direct ecological effects of climate change.