黄土丘陵区不同植被类型下土壤水分动态

目的]探讨黄土丘陵区不同植被类型对土壤水环境分异规律的影响。方法]以陕西省延安市燕沟鸡蛋卯小流域1997年退耕建造的样板坡面为对象,于2009年4—10月对其西坡面,自坡顶向下分布的7种植被类型(苹果园、刺槐林、沙棘灌丛、柠条林、紫穗槐灌丛、荒草地、农地(谷子)),采用土钻法每月中旬监测。结果]生长季(4—10月)0—200cm深度平均土壤含水量大小呈现:紫穗槐灌丛荒草地农地(谷子)刺槐林柠条林沙棘灌丛苹果园。不同植被类型下土壤水分垂直剖面分布有较大差异,在浅层(0—40cm),恢复时段的紫穗槐灌丛、刺槐林下土壤含水量一般高于荒草地,沙棘灌丛、农地(谷子)、苹果园土壤含水量低于荒草地;在中层(40—120cm),荒草地土壤含水量最高,苹果园含水量最低,乔灌林地居中;在深层(120—400cm),只有紫穗槐灌丛、农地(谷子)土壤含水量高于荒草地,其他乔灌林地、苹果园含水量较低。结论]延安地区植被恢复的乔灌林土壤含水量以紫穗槐灌丛偏高,柠条林、刺槐林、沙棘灌丛对深层土壤水分消耗较大,不利于土壤水环境及其永续利用。

Dynamics of Soil Moisture Under Different Vegetation Types in Loess Hilly Area

Objective] To determine the spatial and temporal dynamics of soil moisture under different vegetation types in loess hilly area.Methods] We studied the typical slope which was built in Yangou watershed of Yan'an City, Shaanxi Province in 1997. The soil moisture content was measured using drilling method from April to October in 2009 under seven vegetations(apple orchard, Robinia pseudoacacia forest, Hippophae rhamnoides scrubland, Caragana microphyllas forest, Amorpha fruticosa scrubland, grassland, farmland with Setaria talica) in the middle of each month.Results] The average soil moisture(0-200 cm) in growing season(April to October) was:A.fruticosa scrubland>grassland>farmland(Setaria talica) >R. pseudoacacia forest >C. microphyllas forest >H. rhamnoides scrubland >apple orchard. Soil moisture under different vegetation types was significantly different in the vertical profile. The soil moisture of A.fruticosa scrubland and R. pseudoacacia forest was generally higher than that of grassland. In 0-40 cm, the soil moisture in H. rhamnoides farmland and apple orchard was lower than that in grassland. In 40-120 cm, soil moisture was highest in grassland and lowest in apple orchard. In 120-200 cm, soil moisture of amorpha shrub and farmland was higher than that of grassland, whereas the soil moisture of bushes trees and apple orchard was relatively lower.Conclusion] The results revealed that C. microphyllasforest, R. pseudoacacia forest and H. rhamnoides scrubland made greater consumption of deep soil moisture, being harmful to the soil water environment and its sustainable utilization.