特大丰水年洛川人工林地土壤水分特征研究

根据2004年1月对洛川人工林地和农田0~6 m深度土壤含水量的测定,研究了黄土高原半湿润地区土壤干化现象和土壤水分恢复问题。受2003年特大丰水年降水补给作用,人工林地4 m以上深度的土壤干化现象消失,而4 m以下的土壤干化层依然存在。这就表明,年均降水量600 mm左右的黄土高原半湿润区人工林地存在难以自然消除的土壤深层干燥化现象,成为黄土高原植被生态建设的限制性因素。特大丰水年降水对土壤水分的补给深度一般可以达到4 m深度以下,并且随人工林植被类型和植被生长年限不同而有较大差异。因此要从根本上消灭和减轻土壤干化层的危害,应该通过选择合适的造林树种和控制造林密度加以实现。

Research of soil water character below artificial forest of the heaviest rainfall year in Luochuan area of Yan'an

Based on the determination of soil moisture below artificial forest in Luochuan area of Yan'an,the change of soil moisture from zero to deeper than six meters,the soil dried layer and infiltration depth of rainfall is studied in this paper.As a result of rainfall infiltration,dried layer in the depth between 2 and 4 meters has disappeared,but the soil dried layer under 4 meters keep there.Rainfall infiltration depth of 2003 reached more than 4 meters,according to the depth of dried layer and drying degree.Rainfall infiltration effect continues only a short time,and can't eliminate dried layer.The deep layer soil drought will be carried out by all kinds of artificial forests after certain years,the degree of drying correlate to the type of artificial plants and the density of plantation.We can choose the right artificial plant types and reduce the density of plantation,to lighten or avoid the disadvantageous effect of the dried layer.