【摘要】 准确、高效地掌握草原土壤属性的空间分布能够为草地资源境管理提供基础信息和参考依据。相比于传统土壤调查方法,基于模糊逻辑的土壤—环境推理能够提高野外采样效率和预测制图精度,被广泛应用于数字土壤制图。但由于土壤自身的空间变异性及其与环境条件间的非线性,现有推理模型的稳定性较低,尚未在高寒草原区进行应用。选择新疆巴音布鲁克典型亚高山草原地区约4 km~2区域为研究区,以高程、坡度、坡向、沿剖面曲率、沿等高线曲率、地形湿度指数6个地形因子为土壤环境因子,采用模糊C均值聚类(Fuzzy C-means Clustering,FCM)方法对环境因子聚类,得到9个环境因子组合,并在隶属度值高的环境因子组合中心共设置18个典型点。运用土壤—环境推理方法模拟研究区表层土壤pH值空间分布,其变化范围在7.170～8.186之间。选取35个独立样本进行精度检验(均匀采样点16个,横截面采样点9个,垂直带采样点10个),模拟结果与实测值基本吻合,且基于模糊聚类和土壤—环境推理方法的模拟精度高于普通克里格法和反距离权重法。通过基于模糊逻辑和土壤—环境推理的数字土壤制图方法在小尺度区域的运用验证,结果表明基于典型点的采样方案能够快速、有效地对区域土壤属性进行空间模拟,该方法对于类似小尺度的研究区同样有效。更多还原

【Abstract】 Obtaining spatial distribution of grassland soil properties accurately and efficiently can provide basic information and reference for grassland resource management.Compared with the traditional soil survey method,the soil environment inference model based on fuzzy logic can improve the efficiency of field sampling and accuracy of predictive mapping,which has been widely used in digital soil mapping.However,due to the soil’s spatial variation and its non-linearity with the environmental conditions,the stability of the existing models are relatively low.The models have not been applied in alpine meadow area.In this study,fuzzy C-means clustering(FCM) was used to predict soil pH in the surface layer of grassland soil within a 4 km~2 area in Bayanbulak District,Xinjiang Uyghur Autonomous Region,China.Six terrain factors,including elevation,slope,aspect,planform curvature,profile curvature and topographic wetness index,were clustered.Fuzzy membership of 9 groups of environmental factors were derived to position 18 soil samples in the area with membership larger than 0.9.Then pH distribution was predicted with fuzzy membership model.The pH value of study ranged from 7.170 to 8.186 and was consistent with the measured values.The mapping results reflected continuous changing of soil properties with terrain changing.There were 35 individual soil samples(16 equal-interval sampling points,9 cross-sectional sampling points and 10 sampling points according to altitude) collected as validation data set.The agreement coefficients between observed values and predicted values were high,and the accuracy of FCM model is higher than that of Ordinary Kriging method and Inverse Distance Weighted method.FCM and purposive sampling for digital soil mapping is also suitable for small-scale region.This approach is an efficient digital soil mapping method with satisfactory prediction precision using less samples.It could be possibly applied to the areas with the similar landscape conditions.更多还原