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根据人工林地土壤水分收支平衡方程式,在陕北黄土丘陵区的安塞县水土保持站有设了水分平衡场,对人工刺槐林生态系中的水分平衡状况进行了多年的定量观测。分析结果认为,在半干旱的黄土丘陵区营造人工林之后,由于强烈的蒸发蒸腾和根系深层发育的吸水作用,会使土壤向干燥化发展。深层土壤储水补给调节树木需水的作用逐渐消失,使之只能依靠当年降水进行生长。从这个意义上来看,人工林是在不断地恶化自身生长的土壤水分条件,从而形成生长缓慢、生长量受降水量控制的局面。
According to the soil moisture balance equation of plantation soil, a water balance field was set up in Ansai County Soil and Water Conservation Station in Loess Hilly Region of Shaanxi Province. The water balance in artificial Robinia pseudoacacia forest ecosystem was observed for many years. The results showed that after the artificial forest was built in the semi-arid loess hilly region, the soil would be desiccated due to the strong transpiration and the water absorption of deep root development. Deep soil water supply to adjust the water demand of trees gradually disappear, so that it can only rely on the current precipitation growth. In this sense, plantations are continuously deteriorating their own growth of soil moisture conditions, thus forming a slow growth, growth by the amount of precipitation control situation.