Spatial variability of soil physicochemical properties under different land uses impacted by erosion on karst hillslopes in Southwest China

Abstract

Karst hillslopes are generally characterized by different land uses. Land use and slope position impact soil erosion seriously, which in turn impacts the process of soil development and the patterns of soil properties. However, the impact of land use on soil physicochemical properties and the spatial variations and correlations between them are not fully understood on karst hillslopes. Therefore, nine sites had similar soil types, slope gradients, elevations, slope aspects and previous tillage practices were selected to conduct further research. This study was conducted to quantify the spatial distribution, variability and correlation of soil physical and chemical properties and stoichiometries as impacted by different land uses on a karst hillslope in Southwest China. Soil physical properties were significantly affected by slope position and soil depth. The soil bulk density and clay content increased with soil depth, while the opposite was true for the sand content. For the three land uses, the soil bulk density varied the most at the lower slope position, while clay and sand particles varied the most at the middle slope position. The mean spatial coefficient of variation (CV) of soil physical properties was ranked as sand (11.08%) > clay (7.77%) > bulk density (6.85%) > silt (3.81%). The mean spatial CV of soil chemical properties was ranked as available K (44.49%) > total P (16.77%) > total C (16.31%) > total N (13.09%) > available P (8.45%) > total K (7.51%). Overall, soil physicochemical properties exhibited significant spatial differences with slope location and land use on karst hillslopes. Soil chemical properties had greater spatial variation than physical properties, moreover, there were significant correlations between them. The results not only contribute to a deeper understanding of the impact of land use on the erosion process and mechanism on karst hillslopes but also provide a scientific understanding of the sustainable restoration of karst ecosystems.