Fig. 11 SOC contents from previous studies during 2000-2015 in the east of study area (a), and in the west (b).
SOC data from previous studies were obtained from Ding, (2009), Gao et al., (2016), Gao et al., (2011), Gao et al., (2005), Guo et al., (2007), Han et al., (2007), He and Cao, (2014), Hu et al., (2008), Liang, (2004), Wan et al., (2006), Wu, (2014), Xie et al., (2009), Xu and Gong, (2014), Xu et al., (2006), and Zhang and Wang, (2013).