沙坡头固沙植被若干土壤物理因子的空间异质性研究

Spatial Heterogeneity of Soil Physical Properties in Shapotou Artificial Sand-fixing Vegetation Area

采用地统计学的理论和方法,对沙坡头人工植被表层土壤(0～15 cm, 15～30 cm)物理因子的空间异质性进行了研究.传统统计学分析结果显示:土壤水分、容重平均值在0～15 cm层小于15～30 cm层,毛管持水量、空隙度在0～15 cm层大于15～30 cm层,各因子变异系数在0～15 cm层均大于15～30 cm层.变异函数分析结果表明:土壤水分、土壤容重、土壤毛管持水量和空隙度在0～15 cm层具有明显的空间异质性,表层土壤水分有效变程最大为28.2 m,土壤毛管持水量有效变程最小为13.8 m,各因子自相关部分的空间异质性变化范围在85.3%～99.9%之间,显著大于随机部分的空间异质性.15～30 cm层土壤容重、毛管持水量、空隙度为线性模型.在Kriging插值分析的基础上,绘制了土壤属性各因子的等值分布彩图,清楚直观地表达了各因子在空间上的分布.此外还分析讨论了土壤空间异质性和植被的关系.

With the development of desertification in the world getting more and more serious at present, the exploring of the methods reversing desertification is especially important. The establishment of sand-fixing artificial vegetation in Shapotou area is a good example of controlling desert. The achievement and the pattern of reversing desertification have been recognized by many scientists in the world. The artificial sand-fixing vegetation in Shapotou area was primarily established in 1956. With the succession of the artificial vegetation for more than 40 years, an artificial-natural vegetation ecosystem has been formed. Many former scholars studied this ecosystem in the aspects of plants, soil physical and chemical properties, soil moisture, soil microbiologic crusts and climatology. However, there is little information on spatial variability and scales of soil physical factors in this vegetation area. The present study aims to address the general need for basic information about soil physical factor heterogeneity and to offer important reference information for the further relationship study between soil heterogeneity and vegetation patterns by using principle and methods of geostatistics.\;In Shapotou artificial vegetation area, the soil moisture, bulk density in 0~15 cm layer are less than that in 15~30 cm layer; the capillary moisture capacity and porosity are reversed, whereas the variation coefficients of 0~15 cm layer are more than that of 15~30 cm layer. Results of semi-variance analysis show that there are high degrees of spatial heterogeneity in soil moisture, bulk density, capillary moisture and porosity in 0~15cm layer. The scale of spatial heterogeneity is 13\^8~28\^2 m. The spatial heterogeneity of autocorrelations in total spatial heterogeneity are 83\^5%~99\^9%, which are far more than the spatial heterogeneity of random in total spatial heterogeneity. There is no spatial heterogeneity for each soil physical factor in 15~30 cm layer. The semi-variance function of soil moisture is stochastic model, and the semi-variance function of bulk density, capillary moisture capacity and porosity are linear modals. On the basis of Kriging interpolation, the distribution maps are produced, from which the distributions of each soil physical factors can be seen clearly. The relationship between spatial heterogeneity and vegetation is discussed.