土壤水分植被承载力初步研究

土壤水分植被承载力是干旱、半干旱和半湿润易旱地区土壤水分与植物生长关系调控、合理利用水土资源和林草植被的核心科学问题之一。定位研究密度与植物生长、土壤水分补给和消耗的关系是确定土壤水分植被承载力的实验基础。我们以黄土高原半干旱区16年生人工柠条林为例,进行了实验研究,实验密度包括8700、7100、5100、3200、1600丛/hm2。研究结果如下:土壤水分植被承载力为土壤水分承载植物的最大负荷,它是指在较长时期和特定条件下,土壤水分所能维持相应植物群落健康生长的最大密度;多年生柠条根系虽然可分布到500cm以下土层,但是大部分根量分布在0～150cm土层,根系随深度分布可用指数方程描述;降水最大入渗深度为170～270cm。柠条主要吸收利用0～270cm土层的土壤水分;一年内植物生长与土壤水分的关系可分为4个阶段;柠条密度与生产力或土壤水分补给量为线形关系,与土壤水分消耗量为二次抛物线关系,研究区柠条林地土壤水分承载力为8115丛/hm2,柠条林合理利用方向为保持水土和改善环境质量。

Preliminary Study of Vegetation Carrying Capacity of Soil Water(VCCSW)

VCCSW, short for Vegetation carrying capacity of soil water, is a key and scientific question for rational utilization of soil water and vegetation resource in the arid, semi-arid and semi-humidy region. Field study of density and plant growth, soil water supply and consumption is experimental base for determing vegetation carrying capacity of soil water. The field experiment was conducted in the shrubland having 16-years old artificial Caragana forest in the semi-arid region of Loess plateau to determining the value of VCCSW. Experimental density includes 8 700, 7 100, 5 100, 3 200, 1 600 clumps perhectare. The results showed as following: The term vegetation carrying capacity of soil water can be defined as the ability of soil water to carry vegetation. The limit is the largest density soil water keep plants grow and develop healthily on an annual basis under special conditions. Although the brush root penetrates to a depth of more than 500 cm, most of the root mainly distributed in the upper 150 cm soil, the relationship between root and depth is exponential function. The largest depth of rain penetration is from 170 cm in 2002 to 270cm in 2004. The root soil from which plant roots take and utilize water mainly is the soil layers from 0 to 270 cm soil layer. The relationship between soil water and plant growth can be divided into four stages. The relationship between density and productivity of Caragana forest or the amount of soil water supply in the shrubland is linear, the relationship between density and the amount of soil water consumption in the shrubland is parabola. The value of soil water's carrying capacity is 8 115 clumps per hectare. The best use orientation of perennial Caragana forest is to conserve soil and water and improving environment.