农田土壤有机质空间变异的尺度效应

Scaling effect on spatial variability of soil organic matter in crop land

采用10m×10m高密度网格设计,在面积为10.24hm2的农田内取土壤样本1024个,测定土壤有机质(SOM)含量,通过"再采样"方法,研究改变取样幅度和取样间距对表征土壤有机质变异特征的变异系数和半方差函数参数的影响,分析获得土壤有机质空间变异特征的尺度效应.研究结果表明,10.24hm2取样区内,土壤有机质空间分布表现为弱变异性,CV≤3.43%,但整体含量偏低,SOM≤1.04%;随着采样幅度增加,土壤有机质变异性不同程度增加,变异相关范围和结构性变异比例也不断增大;当采样间距增大时,土壤有机质变异性呈无规律变化,但变异相关范围显著增大,而结构性变异比例呈下降趋势.

Data of 1024 samples collected from a 10.24hm^2 crop land in dense grid of 10m× 10m were used to analyze the scaling effect on spatial variability of soil organic matter（SOM）by re-sampling to ehange sampling extent and resolution. Within the sampled area, soil organic matter had weak variability as CV ≤ 3.43 %, but it was entirely low in the content no more than 1.04%. The results showed that spatial variability of soil organic matter inereased with the ascending extent at different degrees, while spatial dependency and correlation distance increased distinctly. With eontrast to the change of extent, descending resolution can not result in spatial variability of SOM varying orderly, but descended spatial dependency, and increased the correlation distance constantly.