古尔班通古特沙漠腹地土壤水分时空分异研究

Space-Time Distribution of Soil Moisture in Hinter Land of Ggurbantonggut Desert

古尔班通古特沙漠土壤水分补给以积雪融水和雨水为主,土壤水分是维系古尔班通古特沙漠荒漠植被发育最主要的制约因子。选取沙漠腹地典型沙垄为研究区,并分地貌部位布设了土壤水分监测点、植物监测样方以及沙面蚀积监测铁钎和气象观测站,从而形成以土壤水分监测为主的综合监测场。通过野外标定,利用中子水分仪对典型沙垄的不同地貌部位土壤水分动态进行系统监测,结果表明:土壤水分受季节性积雪、降雨、地貌部位、地形起伏、植被盖度等因素的影响而出现明显的空间分异与时间变化。土壤水分的空间差异整体表现为垄间土壤水分高于垄顶,坡下高于坡上。土壤水分的时间变化表现:3～4月为土壤水分的补给期,5～6月为土壤水分快速损耗期,7～10月土壤水分最低,11月～次年2月表层土壤水分积累,而次表层、深层土壤水分相对稳定。

The soil moisture, which is mainly replenished by rainwater and snowmelt, is a crucial factor in maintaining the stability of the fragile ecosystem. Choosing a typical sand dune as study area in the hinterland of Gurbantonggut desert. In different terrain parts that contain the crest, the slope, and the foot of the natural dune, we laid 7 aluminum tubes by which the soil moisture content could be measured with a neutron probe, disposed 7 plant sample areas, 7 iron poles which mark the wind-sand activity correspondingly, meanwhile, set up one weather station. With neutron probe, through field calibration and systemic study on soil moisture, plant sample area and wind-sand activity. The result shows that the space-time distribution of the soil moisture is closely related to terrain parts, the depth of soil, plant cover, rainfall, and the depth of accumulated snow. It is clear that the space distribution difference of the soil moisture. Generally, the soil moisture content of the inter-dune is higher than the dune crest, the lower slope higher than the upper slope. In the vertical direction, the soil moisture content of the surface layer is highest from late autumn to May of next year, the subsurface layer, from June to July, and the deep layer, after the August. In the time aspect, the change of soil moisture content shows that the soil moisture content is higher and the soil moisture content increases from March to April; the soil moisture content decreases rapidly from May to June; the soil moisture content is least from July to October; the soil moisture content is invariable except the soil moisture content of the surface layer in late autumn and winter.