黄土高原白草塬土壤水分特征及对土地利用变化的响应

目的]对黄土高原白草塬土壤水分特征及对土地利用变化的响应进行分析,为该区水资源管理和生态建设提供重要的参考依据。方法]测定并分析白草塬6种利用方式下0—10m的土壤水分,并基于土壤储水量、水分亏缺量及干燥化指数等指标评价土地利用变化的影响。结果]6种土地利用方式0—10m平均含水量表现为:农地荒草地苜蓿地杏林地杏林柠条间作地杏林苜蓿间作地。土地利用变化对土壤水分的影响深度不同,苜蓿地与荒草地的影响集中在0—5m,而包含杏树的利用方式对土壤水分的影响向深层推进甚至可贯穿整个剖面。0—5m除农地外皆有重度土壤干燥化现象;5—10m包含杏树的利用方式干燥化程度较农地、荒草地和苜蓿地严重。结论]农地转变为包含杏树的利用方式后对土壤深层水分有显著的影响,造成土壤水分储水量减少和干燥化现象严重。

Characteristics of Soil Water and Response to Land Use Changes on Baicao Loess Tableland

Objective] The characteristics and response of soil water to land use change(LUC) on Baicao loess tableland were demonstrated to provide information for water resources management and ecological construction. Methods] Soil water contents in 0-10 m profile were measured under six typical land use types (farmland, grassland, alfalfa, apricot, apricot-caragana, and apricot-alfalfa land), and soil water storage(SWS), soil water deficit(SWD) and soil desiccation index(SDI) were calculated. Results] The average soil water contents under the six land use types ranked as farmland > grassland > alfalfa > apricot > apricot-caragana > apricot-alfalfa. The depth of water profiles being influenced by vegetation were different. The effects of alfalfa and grassland on water content concentrated in 0-5 m profile, while the effects of other land use types as apricot, apricot-caragana, and apricot-alfalfa were detected in the whole measured profile, it was as deepen as 10 m. Except for farmland, SDIs were very large for all land use types in 0-5 m depth. In 5-10 m profile, SDIs were comparatively small under farmland, grassland and alfalfa; and were moderate under apricot and apricot-caragana; exhibited the largest under apricot-alfalfa. Conclusion] The conversion from farmland to other land use types with apricot greatly impacted soil water at deep soil profile. These land use types reduced SWS and deteriorated soil water condition by desiccation.