Soil organic carbon stock and change of forests in China 1980s-2010s

Abstract:

Soil organic carbon (SOC) accounts for about 45% carbon stock of global forest ecosystems. The assessment of carbon stock and carbon change of forest soil in China is absence, though huge carbon sinks has been observed in biomass both of China and global forests in decades. This reveals less understanding of SOC than biomass of forests at large scale. We estimated the bulk density, SOC density and carbon stock of forest soil in China based on 1662 soil profiles collected in the first forest soil inventory during 2012-2014. We also analyzed the carbon stock change, and the effect of afforestation to both of the carbon stock change and SOC density change of forest soil in China 1980s-2010s. The results indicate that, for the forest soil in China 2010s, the average bulk density is 1.18 g cm^-3, the mean SOC density is 114.7 Mg ha^-1, and the SOC stock is 23.82 Pg C. During the period of 1980s-2010s, the SOC stock increased 2.45 Pg C, about 81.5 Tg C yr^-1, which is a little less than the biomass carbon change of forests in China. Moreover, not the SOC density, but the increased forest area by afforestation is the major contribution to the SOC sink. The SOC density increased after afforestation for the soil great groups formed under cropland and desert, but decreased for the most soil great groups formed under grassland in 1980s-2010s. Therefore, if both of forest area and SOC density could be increased in China, the carbon sequestration ability would be enhanced and the effect of climate change would be released.