潮河源头不同水源涵养林的土壤饱和导水率

Soil saturated hydraulic conductivity of water conservation forests in Chaohe headwater

为缓解潮河源头断流现象,增强当地水源涵养能力,近年来,在潮河源头实施大面积以涵养水源为目的的植树造林工程。为科学评价水源涵养林的造林成效,了解当地水源涵养林土壤饱和导水率特征,选取当地5种水源涵养林典型林分与撂荒地作对比,利用定水头法测定土壤饱和导水率,运用相关分析研究土壤饱和导水率与土壤理化性质的相关性,运用主成分分析法研究影响饱和导水率的主导因子。结果表明:1)各林分平均土壤饱和导水率由高到低依次为:油松×山杏混交林>侧柏×山杏混交林>落叶松×油松混交林>油松纯林>侧柏纯林>撂荒地,随着土壤深度的增加饱和导水率逐渐降低。2)饱和导水率与土壤密度、黏粒含量呈指数函数关系,与总孔隙度、毛管孔隙度、粉粒含量和砂粒含量呈幂函数关系,与有机质含量呈线性关系。3)土壤密度、有机质、毛管孔隙度和黏粒含量是影响饱和导水率的主导因子。通过各林分与撂荒之间的对比,油松×山杏混交林的土壤饱和导水率最高,侧柏×山杏混交林次之,在今后水源涵养林营造过程中应该优选针阔混交林,尤其是油松×山杏混交林。

[Background]In order to enhance the water source conservation capacity and alleviate the problem of the current interruption at the source of the Chaohe,in recent years,a large number of afforestation projects for the purpose of conserving water resource have been implemented in the source area of the Chaohe. We aim to explore the characteristics of soil saturated hydraulic conductivity( Ks) of water conservation forests in Chaohe source and to assess the effects of soil physicochemical properties on soil saturated hydraulic conductivity. Then we scientifically assess the function of water conservation forests through the research results. [Methods]We measured soil saturated hydraulic conductivity( Ks)of 5-type water conservation forests( Pinus tabuliformis forest land,Larix gmelinii × P. tabuliformis forest,P. tabuliformis × Armeniaca sibirica forest land,Platycladus orientalis × A. sibirica forest land,and P. orientalis forest land) and wasteland using constant-hydraulic head method, analyzed the relationship between Ksand soil physical factors and organic matter with correlation analysis,and assessed the dominant factors affecting Ksby principal component analysis. [Results]1) The average Ks of various forests ranks in descending order as follows: P. tabuliformis × A. sibirica forest land > P.orientalis × A. sibirica forest land > P. tabuliformis × L. gmelinii forest land > P. tabuliformis forest land> P. orientalis forest land > wasteland,showing that Ksdemonstrates a negative exponent as the depth of soil increases. The effect of forest stand on improving surface soil is better than that of deep soil. The P.tabuliformis × A. sibirica forest land has the highest water resource conservation capacity among these 5 forests. 2) Ksis exponentially related to bulk density and clay content,and the soil Ksdecreases with the increase of the content of these two influencing factors. Kshas a power function relationship with total porosity,capillary porosity,silt content and sand content. Kshas a linear relation with organic matter content as well. The effect of organic matter on Ksis to improve the structure of soil and colloids. 3) The dominant factors affecting Ksinclude soil unit weight,organic matter content,capillary porosity and clay content. Soil unit weight,organic matter and capillary porosity have the highest effect on soil saturated hydraulic conductivity,followed by soil clay content. The four factors play important roles in affecting soil saturated hydraulic conductivity. Soil total porosity,silt content and sand content have little effect on soil saturated hydraulic conductivity. [Conclusions] Through the comparison between the forests and the wasteland,we find that the soil Ksof P. tabuliformis × A. sibirica forest is the highest,followed by the P.orientalis × A. sibirica forest land. And it is advised that coniferous and broad-leaved mixed forests should be the priority for future water conservation forests construction,especially P. tabuliformis × A. sibirica forest land.