岷江杂谷脑流域典型天然林和人工林林地水文效应研究

Hydrological Effect of Natural and Planted Forest Stands in the Zagunao Watershed of the Minjiang River Basin

通过野外测定和室内实验分析,研究了岷江杂谷脑流域4种典型天然林和3种人工林地被物和土壤持水特征。结果表明:不同森林植被类型地被物最大持水量存在显著性差异,表现为天然针叶林>天然针阔混交林>中高郁闭度人工针叶林>天然落叶阔叶林>天然常绿/落叶阔叶林>人工天然针阔混交林>低郁闭度人工针叶林;不同森林植被类型0~20 cm土壤饱和持水量差异显著,表现为天然针叶林>天然针阔混交林>人工天然针阔混交林>中高郁闭度人工针叶林>低郁闭度人工针叶林>天然常绿/落叶阔叶林>天然落叶阔叶林;所有森林植被类型土壤水源涵养能力远大于地被物层。人工林与天然林相比,天然林地被物自然含水率和最大持水率分别约为人工林的1.26、1.24倍。在3种人工林中,低郁闭度人工针叶林除自然含水率外,其余地被物水文指标均低于其他2种人工林;中高郁闭度人工针叶林地被物自然含水率、最大持水量和有效拦蓄量最高;人工天然针阔混交林0~20 cm土壤饱和持水量和非毛管持水量最高。鉴于土壤层是区域水源涵养主体,在人工造林时应采取以针叶树种为主,阔叶树种为辅的混交方式,有利于改善林分结构,提高人工林林下植物的多度和丰富度以及地被物和土壤拦蓄降水的能力。

In this study,the water holding capacity of ground cover and soil layer of 4 natural forest stands and 3 planted forest stands in the Zagunao watershed were investigated through field measurements and laboratory experiments.The results show that there was a significant difference in the maximum water holding capacity of ground cover in different forest stands(natural coniferous forest>natural coniferous and broad-leaved mixed forest>dense planted coniferous forest>natural deciduous broad-leaved forest>natural evergreen/deciduous broad-leaved forest>planted-natural coniferous and broad-leaved mixed forest>sparse planted coniferous forest);0–20 cm soil saturated water holding capacity was significantly different among 7 forest stands(natural coniferous forest>natural coniferous and broad-leaved mixed forest>planted-natural coniferous and broadleaved mixed forest>dense planted coniferous forest>sparse planted coniferous forest>natural evergreen/deciduous broad-leaved forest>natural deciduous broad-leaved forest);Soil water conservation capacity was much greater than the ground cover water conservation capacity for all forest stands.The natural water content and maximum water holding capacity of natural forest ground covers were about 1.26 and 1.24 times of that of planted forests,respectively.Among the 3 types of planted forests,hydrological indicators of the ground cover except for the natural moisture of sparse planted coniferous forests were lower than those of the other 2 planted forest stands;The dense planted forest stand had the highest maximum water holding capacity and the effective holding capacity of ground cover;0–20 cm soil saturated water holding capacity and non-capillary water holding capacity of planted-natural coniferous and broad-leaved mixed forest was the highest.Given that the soil layer is the major contributor to regional water conservation,the mixture of coniferous and broad-leaved trees should be adopted in forest plantation,which helps in improving the forest structure,enriching understory plants of planted forests and enhancing water holding capacity of forest ground cover and soil layer.