Ecosystem Carbon Density of Grasslands under Different Grazing Exclusion Ages in Semiarid Region of the Loess Plateau Effects of Different Management Measures on Soil Carbon in Bamboo Forest Ecosystems Changes of carbon pools of alpine sandy Salix cheilophila shelterbelts with stand age Biomass and carbon storage of shrub forests ecosystem in karst city Carbon Concentration Storage and Partition of Populus×euramericana "Zhonglin-46" in Shelterbelts Storage and distribution of soil organic carbon in Dinghushan Biosphere Reserve