金沙江干热河谷不同土地利用方式的土壤水分特征

目的]研究金沙江干热河谷地区不同土地利用方式下的土壤含水量的变化特征,为干热区脆弱生态环境的生态恢复、物种选择提供依据。方法]以金沙江干热河谷典型区云南省元谋县的6种土地利用类型为例,采用TRIME-PICO-IPHTDR每月定期测定土壤水分,每个样地设3个重复,定期分别测定0～20、20～40、40～60、60～80、80～100cm处的土壤含水量。结果]罗望子纯林土壤含水量相对稳定,且含水量较高;银合欢间伐林土壤含水量高于银合欢与其他物种组合的人工林;在草本植物较多的人工林内,土壤含水量均较低。土壤0～20cm含水量变异系数最大,40～60和60～80cm处变异系数旱季比雨季略大。不同林分组合对土壤水分影响明显,Ⅱ和Ⅵ为代表的用地类型土壤含水量较高,Ⅳ和Ⅴ中的20～60cm土壤含水量均下降,Ⅰ和Ⅲ中的80～100cm深度范围内土壤含水量均有小幅下降。结论]土壤含水量随土壤深度的增加而增加,雨季含水量明显高于旱季,雨季土壤含水量变化速率高于旱季,植被郁闭度、草本层盖度是影响土壤含水量的主要因素。

Effect of Different Land Use on Soil Moisture in Dry-Hot Valley of Jinsha River

Objective] To observe variation of soil moisture under different land use patterns in the dry-hot valley of Jinsha River and to provide the basis for restoration of fragile ecological environment and species selection in dry-hot areas.Method] Six kinds of land use patterns in Yuanmou County of Yunnan Province,a typical dry-hot area in the valley of Jinsha River,were selected.TRIME-PICO-IPH TDR was used to determine soil moisture at the depth of 0-20,20-40,40-60,60-80 and 80-100 cm every month.Three duplicates were set up for each plot.Result] Tamarind(Tamarindus indica)had relatively stable and high soil moisture.Leucaena leucocephala for thinned stands had higher soil moisture than Leucaena leucocephala and other species for combined plantation.The plantation with more herbaceous plants had lower soil moisture.The coefficient of variance of soil moisture was highest at the depth of 0-20 cm.The coefficient of variance of soil moisture at the depth of 40-60 and 60-80 cm was higher in dry season than in rainy season.Stands combination had significant different effects on soil moisture.The land use patterns represented by VI and II had higher soil moisture.The soil moisture decreased at the depth of 20-60 cm in the land use patterns represented by IV and V.The soil moisture decreased slightly at the depth of 80-100 cm in the land use patterns represented by I and III.Conclusion] Soil moisture increases with soil depth,and it is higher in rainy season than in dry season.Soil moisture varied more rapidly in rainy season than in dry season.Vegetation density and herb coverage are important factors affecting soil moisture.