Insert Fig. 2
The SOC and TN storages calculated by the FD and ESM methods showed significant variations (Fig. 2). The deviations should be caused by the inequal soil mass that induced by variations of soil BD (Vandenbygaart and Angers, 2006; Wiesmeier et al., 2016). In this study, large sample statistics were carried out on BD, and the results showed that BD increased significantly after deforestation (Fig. 2c,lnRR = 0.09, P < 0.05), and decreased significantly after land restoration (Fig. 2c, lnRR = -0.02,P < 0.05). Therefore, when LUCC increased soil mass (i.e., higher soil BD), the FD underestimated the loss of SOC/TN storage. By contrast, when LUCC decreased soil mass, the FD overestimated the SOC/TN storage. Thus, the ESM were found to be more accurate in capturing SOC/TN storage changes and we only adopted the ESM for the following analysis.