大别山区龙潭小流域土壤全氮和有效磷的空间变异及条件模拟

Spatial variability and conditional simulation of soil total nitrogen and available phosphorus in Longtan watershed of the Dabieshan Mountain, China

土壤属性的空间变异研究对于了解土壤的差异性具有重要意义.运用普通克里格法和序贯高斯模拟方法对大别山区龙潭小流域土壤全氮和有效磷的空间分布进行估值和模拟.结果表明:土壤全氮、有效磷的空间变异均属于中等程度变异,具有强烈的空间自相关,半方差函数拟合的模型均为指数模型,全氮变程为333 m,有效磷变程为474 m.全氮含量主要分布在1.2-1.6 g kg-1之间,占总面积的34.96%,流域的中部和南部较高,北部、东部、西部较低;有效磷含量主要集中在60-100 mg kg-1之间,占总面积的42.17%,流域的西北和南部含量较高.1 000次的序贯高斯模拟显示,普通克里格插值得到的土壤全氮、有效磷的空间分布整体较连续,具平滑效应,序贯高斯模拟的空间分布整体离散,波动性较强.临界概率值为0.50时可以满足条件模拟的要求.随机模拟能够较好地描述土壤属性空间分布的不确定性,为揭示区域土壤属性的空间结构特征提供了有力的工具.

To study on the spatial variability of soil properties for the understanding of the differences in soil is important. Using ordinary Kriging and sequential Gauss simulation methods, we calculated and simulated the spatial distribution of soil total nitrogen and available phosphorus in the Longtan watershed of the Dabieshan Mountain. The results showed that the spatial variability of soil total nitrogen and available phosphorus were moderate with strong spatial autocorrelation. Semivariogram was of exponential model, with total nitrogen variable range of 333 m and phosphorus variable range of 474 m. Total nitrogen content was mainly 1.2-1.6 g kg-~, accounting for 34.96% of the total area, higher in the central and southern watershed. Available phosphorus content was mainly 60-100 mg kg~, accounting for 42.17% of the total area, comparatively higher in the northwestern and southern watershed. The 1 000 sequential Gauss simulation showed that the soil total nitrogen and available phosphorus obtained by ordinary Kriging spatial distributions was smooth, while the result from sequential Gauss simulation was relatively discrete with great volatility. The critical probability value of 0.50 can meet the conditional simulation requirement. Stocbastic simulation can describe the spatial distribution of soil properties uncertainty and provide a powerful tool for spatial structure of regional soil attributes.