Increasing soil carbon stocks in eight typical forests in China

Abstract. Forest soils represent a major stock of organic carbon (C) in the terrestrial biosphere, but the dynamics of soil organic carbon (SOC) stock are poorly quantified, especially based on direct field measurements. In this study, we investigated the 20-year changes in the SOC stocks at eight sites from southern to northern China. The averaged SOC stocks increased from 125.2 ± 85.2 Mg C ha−1 in the 1990s to 133.6 ± 83.1 Mg C ha−1 in the 2010s across the forest sites, with a mean increase of 127–908 kg C ha−1 yr−1. This SOC accumulation was resulted primarily from both leaf litter and fallen logs and equivalent to 3.6–16.3 % of aboveground net primary production. Our findings provide strong evidence that China's forest soils have been acting as significant carbon sinks although their strength varies with forests in different climates.