水力侵蚀对砒砂岩区土壤有机碳空间变异性的影响

Effect of Rainfall Erosion on Spatial Variability of Soil Organic Carbon in Arsenic Sandstone Area

以侵蚀剧烈的砒砂岩区为研究对象,应用地统计学Kriging插值法准确描述水力侵蚀下土壤有机碳空间动态迁移过程来探究侵蚀与碳平衡的关系并为有效治理砒砂岩区坡面水土流失提供科学的参考。结果表明:(1)降雨前后各土层有机碳均随着土层增加而减少,表现为中等变异、空间自相关均为正相关且0-10 cm土层自相关性最大。降雨后0-20 cm土层有机碳含量减少而20-40 cm土层增加,且各土层变异程度均较雨前减弱。(2)降雨前后土壤有机碳分别与高斯模型,球状模型较为拟合,且变程值均随土层增加而增大。降雨前后0-10 cm土层表现均为强烈空间相关性且雨后结构比增大,而10-40 cm均为中等相关性雨后结构比减小。(3)降雨后空间异质性减弱斑块面积变大,总体表现为同一土层坡上侵蚀坡下沉积,而不同土层下0-20 cm土层表现为侵蚀,20-40 cm土层表现为沉积。(4)降雨前后土壤有机碳均与黏粒呈现较显著正相关,其中降雨前0-10 cm土层有机碳与黏粒为极显著正相关,降雨后各土层相关性增强均为极显著正相关。但降雨前后土壤有机碳与粉粒相关性均较小且不显著,与砂粒则基本表现为负相关。

In this paper,the spatial dynamic transfer process of soil organic carbon under hydraulic erosion was accurately described using geostatistics Kriging interpolation method to explore the relationship between erosion and carbon balance,and to provide scientific reference for effective control of soil erosion on the slope surface of Pisha sandstone area.The results indicated that:(1)Before and after the rainfall,the organic carbon of each soil layer decreased with the increase of soil layers,showing medium variation and positive spatial autocorrelation.The maximum autocorrelation occurred in the 0-10 cm soil layer.After rainfall,the organic carbon content of 0-20 cm soil layer decreased while that of 20-40 cm soil layer increased,and the variation degree of each soil layer was weaker than that before rainfall.(2)Before and after rainfall,soil organic carbon was fitted with Gaussian model and spherical model respectively,and the range increased with the increase of soil layers.Before and after rainfall,0-10 cm soil layer showed strong spatial correlation and the nuggrt/sill increases after rain,while 10-40 cm soil layer showed moderate correlation and the nugget/sill decreased after rain.(3)After rainfall,the spatial heterogeneity weakened and the patch area became larger,which was generally manifested by the erosion in the same soil layer.Erosion occurred in the 0-20 cm soil layer,while sedimentation in the 20-40 cm soil layer.(4)Before and after the rainfall,soil organic carbon and clay contents showed a significant positive correlation.A very significant positive correlation was found in 0-10 cm layer before the rainfall,and the correlations increased after the rainfall,showing a very significant positive correlation in all soil layers.However,the correlation between soil organic carbon and silt contents before and after rainfall was weak and not significant,while the correlation between soil organic carbon and sand contents was basically negative.