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 was to investigate the long-term effects of land use intensification effect on plant biomass, soil organic C stocks, and microbial activities in subtropical grasslands. Experimental sites consisted of native rangelands, pine-bahiagrass silvopasture, and intensively-managed grazed bahiagrass (Paspalum notatum) pastures. Each ecological unit (area of ~ 6 ha) was replicated twice and exhibited the same topography, soil type, and climate conditions. Results indicate that silvopasture system has greater litter C mass relative to native rangelands and improved pastures. Despite the greater root biomass (0 to 90 cm soil depth), smaller soil C stocks (75.6 Mg ha^-1, at the 0 to 90 cm depth) were observed in the native rangelands than that in the improved and silvopastures (110 and 101 Mg ha^-1, respectively). Grassland intensification promoted soil C accumulation and microbial activity. Our findings suggest that grassland intensification by using proper fertilization and grazing management can promote soil C accumulation in subtropical ecosystems.