祁连山区不同土地覆被类型下土壤水分变异特征

发布时间：2018-07-15 07:14

【摘要】：结合土壤、植被、地形等要素,建立黑河上游土壤水文观测体系,收集代表黑河上游区域特征的36个定位观测点土壤水分数据和12个气象站的降水数据,采用经典统计方法揭示祁连山区区域尺度上7种土地覆被类型下的土壤水分变异特征。结果表明,降水和植被特征是影响生长期土壤水分的主要因素。降水量大的土地覆被类型上土壤水分值较高。同时土壤水分值越低,降水补给和蒸散发消耗所引起的相对波动就越大,导致其变异性越大。由于植被根系对土壤水分的显著影响,高盖度草地、低盖度草地的土壤水分值在剖面各层变化不大,而农田、草甸、灌丛、林地和裸地土壤水分值随深度变化较明显。草甸、灌丛、裸地土壤水分整体均在夏季最高、秋季次之、春季最低。农田和高盖度草地土壤水分均呈现秋季最高、夏季次之、春季最低。土壤水分变异程度除灌丛外,存在春季变异最大,夏季次之和秋季最小的规律。降水是导致土壤水分值和变异系数在夏、秋季变化的主要因素,而土壤冻融过程则是导致其在春季变化的主要因素。总而言之,祁连山区土壤水分具有明显的空间分布差异与季节变化特征,与不同土地覆被类型的降水条件、植被特性和人工影响都有着密切的关系。
[Abstract]:Combining soil, vegetation, topography and other factors, the soil hydrological observation system was established in the upper reaches of Heihe River, and the soil moisture data and precipitation data of 12 meteorological stations were collected, which represented the characteristics of the upper Heihe River region. The variation characteristics of soil moisture under 7 land cover types in Qilian Mountains were revealed by classical statistical method. The results showed that precipitation and vegetation were the main factors affecting soil moisture in growing period. The soil moisture value of land cover type with high precipitation is higher. At the same time, the lower the soil moisture value, the greater the relative fluctuation caused by the consumption of precipitation recharge and evapotranspiration, resulting in greater variability. Because of the significant effect of vegetation roots on soil moisture, the soil moisture value of high coverage grassland and low coverage grassland changed little in each layer of the profile, but the soil moisture value of farmland, meadow, shrub, woodland and bare land changed more obviously with depth. The soil moisture of meadow, shrub and bare land was the highest in summer, followed by autumn and the lowest in spring. The soil moisture of farmland and high coverage grassland were the highest in autumn, followed by summer and the lowest in spring. Except the shrub, the variation degree of soil moisture was the highest in spring, followed by the lowest in summer and autumn. Precipitation is the main factor that causes the variation of soil moisture and coefficient of variation in summer and autumn, while the process of soil freezing and thawing is the main factor that leads to the change of soil moisture and coefficient of variation in spring. In a word, the spatial distribution and seasonal variation of soil moisture in Qilian Mountains are closely related to the precipitation conditions of different land cover types, vegetation characteristics and artificial effects.
【作者单位】：兰州大学资源环境学院西部环境教育部重点实验室旱区流域科学与水资源研究中心西部环境教育部重点实验室;美国西密歇根大学地理系;
【基金】：国家自然科学基金重点项目(91125010);国家自然科学基金重点项目(41530752)
【分类号】：S152.7

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