黄土高原南部人工植被作用下的土壤水分研究

在大量野外调查和室内测定的基础上,研究了黄土高原南部地区丰水年前后不同人工植被下0～6m土壤水分含量。研究表明,年均降雨量600mm左右的正常年份,该区内杨树林、法国梧桐林和中国梧桐林下1.5～4m土层平均含水量约为90g/kg左右,发育了弱的土壤干化层,4～6m土层平均含水量约为120g/kg,水分状况优于上部土层。麦地和草地下0～6m水分状况良好,未出现土壤干化现象。丰水年充足的降水后所有林木下土壤干层消失,水分得到很好的恢复,说明该区并未形成永久性土壤干层,这为该区人工植被的良好生长提供了必要的条件。但目前加速发展的生态建设及经济林业仍会给该区土壤水分良性循环带来威胁,因此应加强人工植被下土壤水分的长期观测,合理引种、适当栽培,在收益的同时保证生态环境的可持续发展。

Research on soil moisture under effect of artificial vegetation in southern Loess Plateau

Based on abundant field investigation and indoor measurement, soil moisture contents were studied at the depth of 0-6 m under different artificial vegetations in southern Loess Plateau before and after the extreme precipitation. The results indicated that in the ordinary year with annual mean rainfall of 600 mm, the average moisture contents at the depth of 1.5-4 m in poplar woods, chinar woods and Chinese phoenix tree forest were approximately 90 g/kg, and the weak drying soil layer hac developed. The average moisture contents at the depth of 4-6 m were about 120 g/kg, which surpass the upper soil layer. Soil moisture contents at the depth of 0-6 m under wheat and lawn fields were good and no soil drying occur. In the year of abundant rain soil drying under all forest vanishes and soil moisture restores well after extreme precipitation, and soil drying was not permanent, which provides necessary condition for good growth of artificial vegetation in the area. But at present, the acceleratory development of ecosystem construction and economic forestry still bring threats to the virtuous cycle of soil moisture in the area, so it should monitor soil moisture chronically, introduce and plant rationally new species in order to obtain economic benefits and meanwhile to realize sustainable development.