黄土高原人工林土壤水分效应的地带性特征

Zonal characteristics of artificial forest effecting soil moisture on Loess Plateau

为提高黄土高原人工植被建设成效,依据天然植被呈地带性分布的规律,对比分析不同地带人工林与天然植被对土壤水分利用的差异。结果表明:不同植被地带的人工林下均存在一定程度的水分亏缺和干化层现象,其严重程度为森林带<森林草原带<典型草原带。森林带的水分条件可满足林木成材对水分的需求,林木采伐后土壤水分可得到很好恢复;森林草原带可满足10龄以下林木生长对水分需求,10龄以上林分的水分亏缺严重,林木采伐后土壤水分恢复进程缓慢;典型草原带不能满足人工林生长对水分需求。在此基础上,提出了与地带性水分条件相适应的人工林草植被建设模式。

Vegetation construction is one of the major measures to improve eco-environment of Loess Plateau.In order to improve the effectiveness of artificial vegetation construction,comp-arative analysis of the difference between artificial forest and natural vegetation was carried out using soil moisture data according to the distributive law of natural vegetation.The results showed there are different soil moisture deficit s and soil dry-layers under artificial forests of different vegetation zones,the order of serious degree is forest zone<forest-steppe zone<typical steppe zone.Water condition is reluctantly satisfied for the requirement of tree growth in forest zone.In forest-steppe zone,it can satisfy the normal growth of less than10-year age tree and there is serious soil moisture deficit in more than10-year age standing forest.In typical steppe zone,water condition is not enough for tree and shrub’s normal growth,so it is not suitable to develop woodland in large -scale.Recovery of soil moisture is easy after3rainy seasons but as the artificial forest is cut in forest zone,the moisture recovery process is very slow in forest-steppe zone and the recovery is impossible in typical steppe zone.Based on the above results,some constructive models of artificial vegetation are suggested suitable for water conditions in different vegetation zones.