Elevation and total nitrogen are the critical factors that control the spatial distribution of soil organic carbon content in the shrubland on the Bashang Plateau, China
2021
Zhang, Xiao | Li, Xiao | Ji, Xiaodong | Zhang, Zhiqiang | Zhang, Hengshuo | Zha, Tonggang | Jiang, Li
Shrubland has been identified as the most uncertain factor in the C sink in China, but little detail is available regarding the soil organic carbon (SOC) of this significant biome. The effects of influencing factors on the spatial distribution of SOC content have been extensively investigated, but whether these factors reflect a ‘direct’ or ‘indirect’ effect is not clear. In this study, 93 topsoil plots were surveyed to measure the SOC content and the influencing factors, including topography (elevation (Ele), slope gradient (SG), and aspect (SA)), soil conditions (pH, bulk density (BD), soil total porosity (STP), soil water content (SWC), soil temperature (ST), soil salinity (SS), total nitrogen (TN), total phosphorus (TP), and available potassium (AK)), and vegetation (aboveground biomass (AGB)) on the Bashang Plateau in China. The results indicated that the SOC content varied moderately across the entire catchment and was closely related to Ele and all soil conditions (P < 0.05), except for STP. All influencing factors were grouped into four driving indicators of the spatial distribution of SOC content: soil nutrients (TN, TP, and AK), migration of soil water and salt (pH, SWC, and SS), topography and biomass (Ele, SG, and AGB), and basic soil physical properties (BD, STP, and ST). Soil nutrients had the largest relative contribution to the spatial distribution of the SOC content. Ele influenced the spatial distribution of SOC content through direct and indirect effects, and TN had the greatest effect on the SOC content. Ele and TN were the critical factors controlling the spatial distribution of SOC content in the shrubland on the Bashang Plateau, China. The results of this study are a useful supplement to the study of SOC in shrublands and may provide support for the evaluation of the shrubland SOC dynamics after regional vegetation restoration in China and globally.
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