Effects of Vegetation Characteristics and Soil Properties on Soil Organic Carbon after Land Use Changes in the Horqin Sandy Land, China

Abstract

The transformation of land-use practices in semi-arid areas constitutes an effective measure for augmenting soil carbon sequestration and mitigating global warming. However, the impact on soil organic carbon and storage changes after the conversion of sandy areas in arid deserts to other land-use types is still not well understood. The present study investigated the changes in soil organic carbon content and storage, as well as their relationships with influencing factors, following the transition in land cover from mobile sand (MS) to semi-fixed sand (SFS), fixed sand (FS), farmland (FA), grassland (GR), and forest land (FO) at the southern periphery of the Horqin Sandy Land in China. The results showed that the soil organic carbon (SOC) content and soil organic carbon density (SOCD) of the 0-60 cm soil layer increased in other land-use types compared to MS, and the SOC content and SOCD of FA, GR and FO were significantly higher than those of SFS and FS in each land-use type, indicating that positive anthropogenic disturbances favor soil organic carbon sequestration in desert regions, and that their sequestration capacity exceeds that of the natural recovery processes. The SOC content and SOCD of all land-use types showed a maximum range in the surface 0-10 cm soil layer, decreasing with increasing soil depth. Changes in land-use types led to variations in vegetation characteristics (vegetation diversity index [SWI], belowground biomass [BGB]), and soil physicochemical properties (silt content [Silt], total nitrogen [TN], and soil water content [SW]), which, in turn, altered the soil carbon cycle. Our results will further enhance the understanding of the carbon cycle in desert ecosystems, while providing important scientific references for ecosystem restoration and management in arid sandy areas.

Keywords: Land use change, soil organic carbon, Influencing factors, Structural equation modelling