西安地区不同植被下土壤含水量及水分恢复研究

通过大量土壤样品采集和室内水分测定，对西安地区极端降水前后不同植被下0～6m土壤水分含量及其水分恢复进行了研究。结果表明，西安地区杨树林、法国梧桐林和中国梧桐林下大约1．5～4m深度范围内土壤含水量分别为9．3％，9．0％和9．7％，土壤干层已存在，干层厚度约2．5m。麦地和草地下0～6m未出现土壤干层。丰水年极端降水后土壤干层消失，水分得到很好的恢复，原来的土壤干层所在层位恢复后的水分含量明显高予其上部和下部。发育弱的土壤干层并未影响到人工林的正常生长，说明在西安或与西安地区类似降雨量的黄土高原其他地区，种植高大的乔木林是可行的，但应避免更为严重的土壤干层出现。

Research on Moisture Content and Moisture Restore in Different Vegetation in Xi''an Area

Through gathering massive soil samples and determining the moisture content in the lab.,the author had research on the moisture content and the moisture restore in the depth of 0 ~ 6 m in the different vegetation around extreme precipitation in Xi'an area.The research indicates that in Xi'an area in the poplar woods,the plane tree forest and the Chinese parasol tree forest the moisture content in the depth of 1.5 ~ 4 m separately is 9.3%,9.0% and 9.7%,the soil dryer has existed,and the thickness is approximately 2.5 m.In the wheat and lawn field the soil dryer does not appear in the depth of 0 ~ 6 m.In abundant water year after extreme precipitation the soil dryer vanishes,the soil moisture restores well,and the moisture content in the original dryer is obviously higher than the upside and lower part.That the weak-growth dryer does not affect the normal growth of the planted forest indicates in Xi'an area or in other area of loess plateau with similar rainfall amount to the Xi'an area planting big tree forests is feasible,but should avoid a more serious soil dryer appearing.