Native upland pine-grassland communities once dominated the southeastern U.S. Coastal Plain but have been largely replaced by intensive land use practices such as row crop agriculture, plantation forestry, pasture, and urban development. These land use changes generally represent a loss of ecosystem resilience to environmental impacts associated with climate change, including altered temperature, precipitation, and fire regimes. Restoration of natural ecosystem function is key to increasing landscape resilience, but little is known about the long-term potential for such restoration. In this presentation, recent studies in Florida and Georgia are used to describe succession on post-agricultural land during application of fire at historic return intervals (1-2 years). Studies include repeated observations of the plant community during seven years following cessation of tilling, comparison of species composition between native and mature post-agriculture pine communities, and a chronosequence approach to describe plant community succession following abandonment of agriculture over the period of a century, including comparison to native reference sites. Changes in species life history characteristics over time are considered, as well as changes in soil physical and chemical characteristics that are predictive of hydrological function, carbon sequestration, and maintenance of plant productivity.
Results/Conclusions
Repeated observations of plant communities following cessation of intensive disking and with initiation of frequent burning show an initial rapid increase in native plant species richness. However, multivariate analyses showed native pine-grassland and mature post-agricultural communities to remain compositionally distinct, although with considerable overlap in species. The chronosequence approach revealed steady accumulation of perennial native plant species and decrease in ruderal species over a century, gaining similarity to but not equivalence with the native community, indicating that a suite of native plants are unable to reinvade. Soil characteristics also showed steady development toward native conditions, including decreased bulk density, higher infiltration rates, and increased total carbon, demonstrating that such restored communities provide valuable ecosystem services similar to native communities. Many species of rare native animals are thriving in the restored communities, and the fuel structure has proven conducive to frequent prescribed fire mimicking natural ecosystem function. The restored communities provide economically important timber resources and recreational hunting while contributing resilience to the landscape in the face of climate change. However, full restoration of native plant communities and biota that depend on them is not achieved passively through succession and application of fire regimes.