三峡库区典型城郊防护林土壤饱和导水率特征研究

【目的】分析三峡库区土壤剖面饱和导水率的变化特征,了解土壤水分在不同土壤深度的运动规律,为改善防护林造林模式提供科学参考。【方法】选取位于三峡库区尾端的针叶纯林、针叶混交林、阔叶混交林、针阔混交林等典型人工林及荒地,采用恒定水头法测定土壤饱和导水率(K_s),探讨库区典型人工林土壤饱和导水率的特征及其与影响因子之间的关系。【结果】土壤饱和导水率随土层加深呈现出负指数形式的递减规律,各林分土壤饱和导水率由高到低为:针阔混交林>阔叶混交林>针叶混交林>针叶纯林>荒地。土壤有机质含量与土壤饱和导水率呈二次曲线关系,随着土壤有机质含量的增加,平均饱和导水率逐渐增加,但增加速率逐渐降低,当土壤有机质含量达到最大值(18.596 g/kg)以后其增加速率趋于平缓。土壤密度和孔隙度是影响土壤饱和导水率的最主要因素,机械组成为次要因素,其他物理因子的相关性较小。【结论】各土壤理化因子对土壤饱和导水率的影响作用不同,土壤饱和导水率越大,对延缓地表径流的作用越强。在防护林建设过程中适合营造针阔复合型防护林,有利于保持水土、防风固沙、改善环境和维持生态平衡。

Characteristics of soil saturated hydraulic conductivity in classic suburb shelter forests in the Three Gorges Reservoir

【Objective】The change of characteristics in the soil profile saturated hydraulic conductivity was analyzed and the law of movement of soil moisture at different soil depths was understood, which provided a scientific reference for improving the afforestation model of shelter forest.【Method】In this paper, four artificial forests, including coniferous pure forest, mixed coniferous forest, mixed broadleaf forest, mixed coniferous-broadleaf forest and wasteland, were chosen to discuss the characteristics of soil saturated hydraulic conductivity in these four kinds of artifical forests and the relationship of its impact factors with the method of determining soil saturated hydraulic conductivity at the fixed water level.【Result】Soil saturated hydraulic conductivity exhibited a negative exponent as the depth of soil increased and soil saturated hydraulic conductivities of various forests ranked in descending order were as follows:mixed coniferous-broadleaf forest>mixed broadleaf forest>mixed coniferous forest>coniferous pure forest>wasteland. Soil organic matter content and soil saturated hydraulic conductivity are in a quadratic curve. The higher the species richness, the greater the saturation of the soil. As the content of organic matter increased, the average soil saturated hydraulic conductivity increased, but the rapid increase began to slow gradually. When the content of organic matters reached the maximum(18.596 g/kg), the rapid increase became increasingly gentle. Unit weight of soil and porosity are the main impact factors of soil saturated hydraulic conductivity. Mechanical composition is the secondary factor. Other physical factors have no large impact.【Conclusion】Different soil physical and chemical factors have different effects on soil saturated hydraulic conductivity. The higher the soil saturated hydraulic conductivity, the stronger the effect on delay of surface runoff. Therefore, in the construction of the protection forest, it is suitable to build a compound protective forest, which can help to maintain soil and water, wind proof and sand fixing, and improve environment and maintain ecological balance.