丰乐河流域表层土壤有机碳空间变异特征研究

Spatial Variabilities of Topsoil Organic Carbon in Fengle River Basin

土壤有机碳含量空间变异特征的研究对于区域土壤资源的可持续利用具有重要意义。在Arc GIS技术的支持下对丰乐河流域表层土壤(0~20 cm)有机碳(SOC)含量的空间变异特征进行了研究。结果表明:丰乐河流域SOC含量为14.31±4.50 g·kg^(-1),不同土地利用类型下SOC含量差异显著(p<0.01)。其中,林地SOC含量的均值最大,为15.58±5.93 g·kg^(-1);水田和旱地次之(分别为15.39±3.09 g·kg^(-1)、11.46±3.04 g·kg^(-1));园地最小(11.09±3.48 g·kg^(-1))。流域SOC含量变异系数(CV)为31.44%,属中等变异程度。其中,林地的CV为38.06%,在4种土地利用类型中为最大;园地、旱地的CV分别为31.38%、26.52%;水田的CV最小,为20.07%,表明人类活动影响表层土壤有机碳含量的变异程度。研究区表层SOC半方差模型为球状模型,块金效应小于25%,存在强烈的空间自相关性,且空间变异主要由结构性因素引起。SOC含量空间分布的各向异性显著,在南北方向上变异程度最为剧烈。SOC含量空间分布表现为东北部、西南部较高,西北部偏低,总体呈斑块状分布。

The study of spatial variability of soil organic carbon content is important for sustainable utilization of regional soil resources. Spatial variability of SOC（ soil organic carbon） content in the surface layer of Fengle river basin was analyzed using the Arc GIS method. Descriptive statistics of the results shows that the soil organic carbon content in this area is averagely 14. 31 with SD of 4. 50（ g·kg^（-1））. Analysis of variance showed that the effects of land use on soil organic carbon were significant（ p〈 0. 01）. In terms of different land use patterns,average organic carbon content in forest land soil（ 15. 58 ± 5. 93 g·kg^（-1））is notably higher than that in paddy field and dry land（ 15. 39 ± 3. 09 g·kg^（-1） and 11. 4 ± 3. 04 g·kg^（-1））,which is then remarkably higher than that in garden land（11. 09±3. 48 g·kg^（-1））. The coefficient of variation（ CV） was 31. 44%. Its variance belongs to a moderate level. Moreover,forest land boasts of the greatest dimensional variability with a variability index of 38. 06%,much higher than that of garden land and dry land（ 31. 38% and 26. 52%）. The CV of the paddy field was20. 07%,in four kinds of land use types,is the minimum. The result indicated that the variability of topsoil organic carbon content was affected by human activities. The soil organic carbon semivariance model is spherical model. Moreover,geostatistical analysis suggests that the study area was very strong in spatial auto correlation and structural factors played a dominating role in spatial variability of soil organic carbon,which was significant in anisotropy. And in the northern and southern direction,the degree of variation is most severe. The spatial distribution of soil organic carbon content is higher in the northeast,southwest,and lower in the northwest. The content of soil organic carbon showed a maculosus distribution approximation.