黑河中游荒漠-绿洲过渡带斑块状植被区土壤水分变异特征分析

Spatial Variability Characteristics of Soil Moisture of Patch Vegetation Area ionn Desert-oasis Ecotone in the Middle Reaches of the Heihe River

土壤水分是荒漠-绿洲过渡带斑块状植被生长发育和维持稳定的主要环境因子.基于甘肃临泽县荒漠-绿洲过渡带斑块状植被区2014年雨季前、雨季后72个采样点0～100cm土壤层含水量的实测数据,并结合中国生态系统研究网络临泽内陆河流域研究站的野外气象观测资料,利用经典统计学和变异函数理论,分析了荒漠-绿洲过渡带斑块状植被区土壤水分的时空变异特征.研究表明：1）雨季前、雨季后土壤水分在垂直分布上随着土层深度的增加而增大,而对于同一土层的土壤含水量均值,雨季后分别小于雨季前;2）雨季前、雨季后0～20cm土壤水分的变异分别为强变异、中等变异,而其余各层土壤水分的变异均为强变异;3）雨季前、雨季后土壤水分的变异函数理论模型为球状或指数模型,虽然雨季前、后同一土层的土壤水分模型大多不一致,但是其模型都能较好地反映土壤水分的空间结构特征;4）雨季前、雨季后由随机因素引起土壤水分的空间变异较小,而土壤质地、植被斑块格局等结构性因素是引起土壤水分空间变异的主要因素.其中,雨季前,在64.2～145.3m尺度范围内,土壤水分75.6%～99.7%的空间变异由空间自相关引起;雨季后,在79.9～154.2m的尺度范围内,土壤水分76.9%～92.9%的空间变异也由空间自相关引起.

Soil moisture is the main environmental factor to keep vegetation growth and stability.Based on the field observation＇s soil moisture data of the soil layer of 0-100 cm in depth including72 sampling points in the patch vegetation area of desert-oasis ecotone before and after the rainy season in 2014 and the meteorological data of the observation meteorological station in continental river basin,the spatial and temporal variability characteristics of soil moisture are studied by the classical statistics and variation function theory.The results show that the soil moisture content before and after the rainy season is increasing with the increase of soil depth,and the average moisture after the rainy season is less than that before the rainy season in the same layer.The variation of soil moisture of the soil layer of 0-20 cm in depth before and after the rainy season is medium and strong,respectively,but that of the others belongs to strong variation.The semivariogram models of soil moisture before and after the rainy season are exponential or spherical models,although which of soil moisture in the same layer before and after the rainy season is mostly different,the model can clearly reflect the characteristics of the spatial structure of soil moisture.The spatial variability of soil moisture caused by random factors is litter,but structural factors such as soil texture,vegetation patches pattern are major factors.Meanwhile,it is about 75.6%～99.7% of the space mutation of soil moisture caused by spatial autocorrelation before the rainy season,and the space mutation of soil moisture caused by spatial autocorrelation after the rainy season is 76.9%～92.9%.