Increased soil organic carbon storage in Chinese terrestrial ecosystems from the 1980s to the 2010s

摘要

Soil stores a large amount of the terrestrial ecosystem carbon (C) and plays an important role in maintaining global C balance.However,very few studies have addressed the regional patterns of soil organic carbon (SOC) storage and the main factors influencing its changes in Chinese terrestrial ecosystems,especially using field measured data.In this study,we collected information on SOC storage in main types of ecosystems (including forest,grassland,cropland,and wetland) across 18 regions in China during the 1980s (from the Second National Soil Survey of China,SNSSC) and the 2010s (from studies published between 2004 and 2014),and evaluated its changing trends during these 30 years.The SOC storage (0-100 cm) in Chinese terrestrial ecosystems was 83.46±11.89 Pg C in the 1980s and 86.50 ± 8.71 Pg C in the 2010s,and the net increase over the 30 years was 3.04 ± 1.65 Pg C,with an overall rate of 0.101 ± 0.055 Pg C yr-1.This increase was mainly observed in the topsoil (0-20 cm).Forests,grasslands,and croplands SOC storage increased 2.52 ± 0.77,0.40 ± 0.78,and 0.07 ± 0.31 Pg C,respectively,which can be attributed to the several ecological restoration projects and agricultural practices implemented.On the other hand,SOC storage in wetlands declined 0.76 ± 0.29 Pg C,most likely because of the decrease of wetland area and SOC density.Combining these results with those of vegetation C sink (0.100 Pg C yr-1),the net C sink in Chinese terrestrial ecosystems was about 0.201 ± 0.061 Pg C yr-1,which can offset 14.85％-27.79％ of the fossil fuel C emissions from the 1980s to the 2010s.These first estimates of soil C sink based on field measured data supported the premise that China's terrestrial ecosystems have a large C sequestration potential,and further emphasized the importance of forest protection and reforestation to increase SOC storage capacity.