祁连山排露沟流域青海云杉(Picea crassifolia)林土壤水分特征

Soil moisture variation characteristics of Picea crassifolia forestry in Pailugou Watershed of Qilian Mountains

土壤水分是植物生长的关键水分来源,对生态系统的演变具有重要作用。选取祁连山排露沟流域青海云杉(Picea crassifolia)林为研究对象,通过建立固定样地,进行了两个生长季的分层(0~10、10~20、20~30、30~40、40~50、50~60 cm)土壤含水量监测。结果表明:(1)在各海拔青海云杉林之间,土壤含水量差异很大,海拔3 300、3 100、2 900、2700、2 500 m处土壤水分含量依次降低。(2)青海云杉林土壤含水量随土壤剖面深度的增加呈降低趋势,土壤含水量变异系数随土壤深度增加有递减的趋势;0~10 cm土层土壤含水量的变异系数最高。相同土层的含水量变异系数海拔2 500 m处>2 700 m处>2 900 m处>3 100 m处>3 300 m处。(3)小流域空间尺度内,海拔、降水、温度和土壤特性等因素共同作用,影响着土壤含水量的差异,使土壤含水量的空间分布具有随海拔升高而增大的变化规律。

Soil moisture is the key source for plant growth and plays an important role in ecosystem dynamics.This study selected Picea crassifolia forest with different elevation gradients in Pailugou catchment of Qilian Mountains as the research objects,and the soil moisture content was monitored by stratification during the two consecutive growing seasons(0-10,10-20,20-30,30-40,40-50,50-60 cm)by establishing fixed plots. The results showed that:(1)During the samples of Picea crassifolia forest,there is a great difference in soil moisture content,which is shown as the following elevation gradient:soil moisture at 3 300 m>3 100 m>2 900 m>2 700 m>2 500 m.(2)Both soil moisture content and the coefficient of variation(CV)were decreased with the increase of soil depth at different elevation gradients. In the range of 0~10 cm soil layer,the CV of soil moisture content is the highest. The order of variation coefficient of soil moisture content in the same soil layer is basically in order of elevation CV at 2 500 m>2 700 m>2 900 m>3 100 m>3 300 m.(3)On the spatial scale of small watershed,elevation,precipitation,temperature,and soil characteristics affect the differentiation of soil moisture content,which makes the spatial distribution of soil moisture content increase with elevation,and therefore the vegetation change.