陕北黄土区不同降水量地点微地形土壤干燥化效应研究

Soil Desiccation Effects of Micro-Topographic in Different Precipitation Locations in the Loess Region of Northern Shaanxi Province

【目的】为揭示降水量及微地形对陕北黄土区深层土壤水分的影响,促进植被恢复的可持续发展。【方法】以陕西省吴起县降水量低的王洼子和降水量高的白豹流域的原状坡、缓台、浅沟、切沟、塌陷、陡坎6种微地形为研究对象,对比分析王洼子和白豹各微地形0~10 m土层土壤水分变化规律、干燥化程度及区域分布特征。【结果】不同降水量地点及不同微地形土壤含水量均存在显著差异,且土壤含水量随土层深度增加总体呈现先降低后升高的趋势。王洼子和白豹不同微地形土壤含水量分别介于5.82%~8.88%和10.42%~14.62%,切沟、缓台和塌陷的土壤含水量、有效贮水量及水分过耗量均优于原状坡、浅沟和陡坎。王洼子土壤干燥化指数均值为68.72%,呈现严重干燥化,各微地形土壤干燥层厚度介于970~1 000 cm,干燥化程度依次为陡坎>浅沟>原状坡>缓台>塌陷>切沟,白豹土壤干燥化指数均值为6.54%,呈现轻度干燥化,各微地形土壤干燥层厚度介于280~900 cm,干燥化程度依次为原状坡>陡坎>浅沟>塌陷>缓台>切沟。【结论】降水量及微地形对深层土壤含水量及干燥化程度影响显著,植被恢复重建可充分利用切沟、缓台和塌陷等土壤水分环境较好的微地形。

【Objective】The aim of this study was to figure out the effect of precipitation and micro-topography on deep soil moisture content,then accelerate the sustainable development of vegetation restoration in local loess region.【Method】The soil moisture content,desiccation degree and regional distribution was analyzed in 0~10 m soil layer of 6 different kinds of micro-topography in terms of undisturbed slope,platform,shallow gully,gully,collapse and scarp,located at Wangwazi(low precipitation) and Baibao(high precipitation) catchment in Wuqi County of Shaanxi province.【Result】The soil moisture content was different significantly in different precipitation locations, as well as in different micro-to-pographies. With the increase of soil depth,the soil moisture content generally decreased first and then increased. The soil moisture content of Wangwazi and Baibao in different micro-topographies was 5.82%-8.88% and 10.42%-14.62%,respectively. The soil moisture content,available soil moisture storage and soil moisture overconsumption in gully,platform and collapse were all better than that in undist-urbed slope,shallow gully and scarp. In Wangwazi,the soil desiccation index was 68.72%,which was serious desiccation. The soil thickness of desiccation in different micro-topographies was between 970 ~1 000 cm,and the order of soil desiccation degree was as follows:scarp>shallow gully>undisturbed slope>platform>collapse>gully. While in Baibao,the soil desiccation index was 6.54%,which was mild desiccation.The soil thickness of desiccation in different micro-topographies was between 280~900 cm,and the order of soil desiccation degree was as follows:undisturbed slope >scarp >shallow gully >collapse >platform >gully.【Conclusion】The deep soil moisture content and desiccation degree were affected significantly by precipitation and micro-topography. The micro-topography with good soil moisture environment,such as gully,platform and collapse,could be used efficiently in vegetation restoration and reconstruction.