川中丘陵县域土壤pH空间变异及影响因素分析——以四川仁寿县为例

SPATAIL VARIABILITY OF SOIL pH AND ITS INFLUENCE FACTORS AT A COUNTY SCALE IN HILLY AREA OF MID-SICHUAN BASIN—— A CASE STUDY FROM RENSHOU IN SICHUAN

利用2012年在仁寿县采集的555个表层土样（0~20cm）,应用地统计学方法分析了该县域尺度表层土壤pH值的空间变异特征;并采用方差分析和回归分析量化主要影响因素对土壤pH值空间变异的影响程度。结果表明：研究区土壤pH值在4.02~8.14之间,平均为6.80,总体上以中性和碱性土壤为主;变异系数为14.48%,属中等程度的空间变异性。地统计分析表明,研究区土壤pH值变异函数的最佳理论模型为球状模型,具有中等程度的空间自相关性,且空间自相关范围较大。方差分析和回归分析表明,土壤类型、成土母质和土地利用方式是显著影响土壤pH值的主要因素。其中,成土母质和土地利用方式分别能独立解释76.2%和4.8%的土壤pH值空间变异。土壤类型的解释能力与分类级别有关,土类、亚类和土属可分别独立解释41.3%、57.3%和83.7%的土壤pH值空间变异,因而能反映成土过程和母质特性的土属是研究区土壤pH值空间变异的主控因素。研究结果可为川中丘陵县域尺度土壤pH空间变异分析及区域生态环境管理与建设提供有益参考。

Based on 555 topsoil samples（0-20cm）collected from the Renshou county of Sichuan Province in 2012,spatial variability of topsoil pH at the county scale in the hilly area of Mid-Sichuan Basin was analyzed using geo-statistics,while variance analysis and regression analysis were employed to quantify the extent of impact of the main factors on soil pH variability.Results show that soil pH values in the study area range from 4.02 to 8.14,with an average of 6.80.Overall,41.08% and 32.07% of soil samples are neutral and alkaline soils,respectively.Coefficient of variation is 14.48%,indicateing a moderate spatial variability.Geostatistical analysis showed that the best theoretical model is the spherical model with a nugget/sill ratio of 0.302,suggesting that soil pH has a moderate spatial dependence,and structural factors play a dominant role while random factors also have an impact on spatial variability of soil pH in the study area.The range is 52.7 km,suggesting soil pH has a large range of spatial autocorrelation.Variance analysis shows that land use type,soil type and parent material have significant impacts on soil pH.Land use type and soil parent materials are able to explain 4.8% and 76.2% of the spatial variability of soil pH,respectively.The explanatory power of soil type is related with soil classification.Soils in lower soil categories of the soil classification are more capable of explaining the spatial variability of soil pH.Soil group and soil subgroup are able to independently explain 41.3% and 57.3% of soil pH variability respectively,while soil genus independently explain 83.7% because soil genus is classified based on both soil-forming process and characteristics of parent materials which have a great effect on soil pH.Therefore,it is advisable to use soil genus as main influencing factors in predicting and assessing spatial distribution of soil pH value at the county scale in the hilly area of Mid-Sichuan Basin.This result provides useful information for management and construction of ecological environment for the study area.