土壤有机碳作为土壤的重要组成部分,其空间变异对土壤资源的合理利用、土壤碳循环等具有重要意义。选取河北坝上地区典型草地坡面,通过实地采样、试验分析、地统计与空间插值制图,探究农牧交错带坡面土壤有机碳含量空间变异特征及机理。结果 表明:坡面土壤有机碳含量平均为2.72%,空间差异较大,在坡形上表现为凹坡>偏凹坡>偏凸坡>凸坡,在坡位上表现为坡下>坡中>坡上。随着深度的增加,土壤有机碳含量逐渐减少,且土壤有机碳的空间变异有增强趋势。表层变程为49.8 m,其他深度变程范围100.90～108.50 m,表明表层土壤有机碳空间自相关的距离明显小于其他深度。与较大尺度相比,该坡面尺度土壤有机碳主要受地形、土壤性质、植物根系等结构性因子影响,各层均表现出强空间自相关。地形控制着坡面的水热再分配,在其作用下土壤颗粒的流失、迁移、堆积以及根系生物量在不同深度的生长差异引起有机碳的空间变异,人类活动主要影响表层土壤。
Soil organic carbon(SOC)is an important component of soil, and its spatial variability is of great importance to the rational utilization of soil resources and the soil carbon cycle. In order to explore spatial variation characteristics and mechanism of SOC at the slope scale in the agro-pastoral transition zone, field sampling, experimental analysis, geostatistics and spatial interpolation mapping were implemented on a typical grassland slope in Bashang region of Hebei Province. The results showed that the average content of SOC was 2.72%, and the spatial difference was obvious; the SOC content was the highest on the concave slope, and followed by sub-concave, sub-convex, convex slope, and the SOC content decreased with elevation; SOC content decreased with depth, and the spatial variation of SOC tended to increase; the range was 49.8 m in the surface layer, and it varied from 100.90 m to 108.50 m at other depths, indicating that the spatial autocorrelation distance of surface SOC was obviously shorter than other depths; compared with other larger scales, the SOC at this slope scale mainly affected by structural factors such as topography, soil properties and roots and SOC at all depths shows the strong spatial autocorrelation. Topography controls the redistribution of water and heat on slopes. Under the influence of topography, the loss, transportation and accumulation of soil particles and the differences of root biomass at different depths affected the spatial variability of SOC at slope scale. Human activities mainly affected the surface soil.
