Landscape-scale spatial variability of soil organic carbon content in a temperate grassland: Insights into the role of wind erosion

Understanding the spatial variability of soil organic carbon (SOC) and its main influencing factors is crucial for sustainable land use management and climate change mitigation. Existing studies mostly focus on the influence of environmental factors on the spatial variability of SOC, while little attention has been paid to the effects of wind erosion which has important influences in arid and semi-arid landscapes. In this study, spatial variability of SOC content at landscape scale and its main influencing factors were analysed at 0-1 cm and 1-6 cm in a typical temperate grassland. Results show that SOC content ranges from 0.45% to 4.11% and is higher at 0-1 cm. SOC presents strong and moderate spatial autocorrelation at 0-1 cm and 1-6 cm, respectively. SOC is high in part of the hilly area, and low in the west plain and southeast undulation. Elevation and vegetation coverage have significantly positive effects on SOC. SOC varies with land uses with the order that arable land (AL) < heavily grazed grassland (HG) < moderately grazed grassland (MG) < lightly grazed grassland (LG) < ungrazed grassland (UG) at 0-1 cm and AL < HG < MG < UG < LG at 1-6 cm. Under the same land use, SOC is generally the highest in the flatland at both layers and lowest in the leeward slope at 0-1 cm and the windward slope at 1-6 cm, respectively. Wind erosion and deposition can both alter SOC content and increase its spatial variability. SOC is high in areas without wind erosion and deposition and decreases with erosion and deposition rates due to the selective erosion and remote region sourced deposition materials which generally have low SOC. Such effects have important influence on land productivity, global carbon cycle and climate change, and it could not be neglected in carbon accounting.