Effects of vegetation rehabilitation on soil organic and inorganic carbon stocks in the Mu Us Desert, northwest China

In arid and semiarid areas, the importance of soil inorganic carbon (SIC) is at least as high as that of soil organic carbon (SOC) in affecting the regional carbon budget following vegetation rehabilitation. However, variations in SIC have been uncertain, and few studies have analyzed the interactions between the SOC and SIC pools. We measured SIC, SOC, C-13-SIC, and C-13-SOC after planting Mongolian pine (MP) and Artemisia ordosica (AO) on shifting sand land (SL) over 10years in the Mu Us Desert, northwest China. The results showed that, compared to SL, SIC stocks at 0-100cm in MP and AO lands significantly increased by 12.6 and 25.8Mgha(-1), respectively; SOC stocks in MP and AO lands significantly increased by 24.0 and 38.4Mgha(-1), respectively. Both C-13-SIC and C-13-SOC in the 2 plantation lands were significantly lower than those in SL were. All 315 samples exhibited a negatively linear relationship between SIC content and C-13-SIC (R-2=.70, p<.01) and showed positively linear relationships between SIC content and SOC content (R-2=.69, p<.01) and between C-13-SIC and C-13-SOC (R-2=.61, p<.01). The results demonstrated that vegetation rehabilitation on SL has a high potential to sequester SIC and SOC in semiarid deserts. The reduction in C-13-SIC and the relationship of SIC with C-13-SIC following vegetation rehabilitation suggested that SIC sequestration is likely caused by the formation of pedogenic inorganic carbon. The relationships between SIC and SOC and between C-13-SIC and C-13-SOC implied that the pedogenic inorganic carbon formation may be closely related to the SOC accumulation