The soil organic carbon density spatial heterogeneity and its impact factors under different karst landforms

To study the spatial heterogeneity and effect factors of soil organic carbon density (SOCD) under different karst landforms, total of 1,173 samples were taken from different karst landforms including Puding (KP), Xingyi (KPCD), Guanling (KC), Libo (KVF) and Yinjiang (KTV) in Guizhou Province. SOCD characteristics in lands with different vegetation types, land uses and soil types under different karst landforms were analysed. The relationship between SOCD and environment factors was analysed via redundancy analysis. The results indicate that there is a larger discrepancy of SOCD among difference karst landforms types, and this distinction decreased gradually with the increasing of soil depth. The SOCD in soil horizons (0-100 cm) of KPCD, KP, KTV, KC and KVF were 11.10 kg·m−2, 8.43 kg·m−2, 8.13 kg·m−2, 7.06 kg·m−2 and 7.06 kg·m−2, respectively. Soil thickness and rock exposure rate are critical factors affecting SOCD in karst regions.