Impacts of Land Use Change On Ecosystem Carbon in Subtropical Grassland Ecosystems.

Land use intensification often has impacts on plant communities and soil characteristics leading to a change in ecosystem carbon (C) cycling, especially on soil C storage. The objective of this research is to investigate the long-term effects of land use change on plant biomass, soil organic C stocks and characteristics, and on microbial community structure and activities in subtropical grasslands. Experimental sites include three grassland ecosystems: native rangelands, pine-bahiagrass silvopasture, and intensively-managed grazed bahiagrass pastures (improved pasture) receiving nitrogen (N) fertilizer. Results indicate that silvopasture system has greater litter C mass and soil C associated with the mineral fraction relative to native rangelands and improved pastures.  Data also shows that despite greater root biomass (0 to 100 cm soil depth), soil C stock and particulate organic C in native rangelands is smaller than improved pastures. These findings suggest that proper fertilization and grazing management may promote soil C accumulation in subtropical ecosystems.