Net effects of China’s five key ecological stewardship projects on carbon sequestration in 2001-2010

Background/Question/Methods: Terrestrial ecosystems play an integral role in the global carbon cycle. Long-term over- and misuse of forests and grasslands lead to large-scale carbon loss from ecosystems, but also indicate the vital need for carbon sequestration in areas of carbon loss. Consequently, national scale ecological stewardship projects can be planned, and implemented and managed over the long-term to sequester carbon. During the first decade of the 21st century, as a result of China's reformed ecosystem management policy, five national key ecological stewardship projects (i.e., Three-North Shelter Forest Program 4th Phase, Yangtze River Shelter Forest Project and Zhujiang River Shelter Forest Project 2nd Phase, Natural Forest Protection Project, Grain for Green Program, and Beijing and Tianjin Sand Source Control Project) were gradually initiated. In the present study, based on a large-scale investigation of forest, shrub and grassland biomass, soil density and literature surveys, carbon stock increase in the project regions, project contribution to CO₂ atmospheric absorption and climate change mitigation (i.e. carbon sequestration) were estimated. Furthermore, a net greenhouse gas budget accounting model, which take the projects’ carbon sequestration, carbon cost and GHG leakage together in to consideration, was built to estimate the net contribution to global warming mitigation of the projects.

Results/Conclusions: Results showed total carbon stock increase in the five ecological stewardship project regions reached 1353Tg in the beginning of the 21st century, and represented 55% of the ecosystem carbon sink in China during the project years. The decade total carbon sequestration for the five projects was 916 Tg C, almost 67.7% of the carbon accumulation in the project regions, which indicated the project importance in CO₂ mitigation, not only in the project area, but also on national scale. The carbon cost from afforestation and pastureland governance within the project boundary and carbon leakage out of the boundary countervailed 0.31% to 25.5% (8.24% - 8.66% in average) of the carbon sequestration of different projects, and resulted in a total net carbon sequestration of 837 – 840 Tg Ce from the five projects. Our results also suggested the project required relatively low economic costs compared with mitigation efforts imposed on energy or industrial sectors, and could make greater contributions to GHG mitigation and corresponding ecological services in the future, e.g. the 2030 to 2050 period. Therefore, China's experience implementing key ecological stewardship projects and corresponding policies might serve as a reference for other parts of the world facing carbon loss challenges.