五道梁高寒草原土壤水分和植被盖度空间异质性的地统计分析

Spatial Heterogeneity of Soil Moisture and Vegetation Coverage of Alpine Grassland in Permafrost Area of the Qinghai-Tibet Plateau

青藏高原高寒草原区,由于长期冻融和地下冰的存在形成了独特的生态水文结构,土壤水分是控制高寒草原生态过程的关键因子。利用地统计学对多年冻土区高寒草原土壤表层含水量和植被盖度的空间变异性进行研究,结果表明,高寒草原生态系统浅层剖面（0~50 cm）土壤水分和植被盖度均符合正态分布,土壤含水量沿垂直方向逐渐增大,介于19.43%~25.37%之间,变异系数介于23.77%~40.92%;植被盖度具有强变异性,变异系数为47.99%。0~50 cm土壤含水量具有高度的空间异质性,其中91.1%的空间异质性是由空间自相关部分引起的,主要体现在10~190 m的中尺度上;植被盖度在研究尺度上具有中等程度的空间自相关,植被盖度随机部分的空间变异性占总空间变异性的比例为34.2%,主要体现在〈10 m的尺度内。各向异性分析表明,土壤水分和植被盖度具有明显的各向异性,其空间格局有明显的差异。

Alpine grassland in Qinghai-Tibetan plateau has special eco-hydrological structure due to long term freeze-thawing and existence of ground ice,where soil moisture is the key ecological factor controlling ecological process.In this paper,the spatial variability of soil moisture in permafrost area was investigated based on geo-statistical theory and methods.The research was carried out in an alpine grassland environment in permafrost area.The results indicated that the distribution of surface soil moisture and vegetation coverage was normal distribution.The soil moisture at the 0-50 cm soil layer increased with the increase of depth was,on average,19.43%-25.37%,and the variable coefficient was 23.77%-40.92%.The variability of vegetation coverage was strong,with the variation coefficient being 47.99%.There was high degree of spatial heterogeneity of surface soil moisture.The auto-correlation factors mainly at 10-190 m scale occupied about 91.1% spatial heterogeneity.The autocorrelation of vegetation coverage spatial heterogeneity in total spatial heterogeneity was 65.8%,and the distance of spatial autocorrelation in vegetation coverage was found within distance from 10-60.3 m.There existed a stronger anisotropic structure in E 0° and N 90° directions in both soil moisture and vegetation coverage,which indicated soil moisture and vegetation coverage had complex spatial pattern.