兰州市南北两山5种典型人工林土壤的渗透特性

Soil Infiltration Characteristics Under Five Forest Types in Southern and Northern Mountains of Lanzhou City

[目的]探讨不同树种组成的人工纯林和混交林在生长过程中对土壤渗透特性的改良程度,为该区域人工林营建过程中树种选择及现有林分的抚育管理提供科学依据。[方法]采用双环渗透法对甘肃省兰州市南北两山5种典型人工林分类型(侧柏林、新疆杨林、刺槐林、侧柏+刺槐混交林和新疆杨+刺槐混交林)的土壤渗透特性(土壤初渗速率、稳渗速率、平均渗透速率和渗透总量)进行了研究。[结果]随土层深度(0—80 cm)的增加,土壤渗透性逐渐降低。不同林分类型土壤渗透性均表现为:新疆杨+刺槐混交林>侧柏+刺槐混交林>刺槐林>侧柏林>新疆杨林,混交林大于纯林;通用经验方程对各林分土壤渗透性的拟合效果最好,比较适合于描述研究区5种人工林土壤水分入渗过程,Horton方程次之,Kostiakov方程最差。土壤渗透性与土壤初始含水率、总孔隙度、有机质含量、全氮、无机氮呈极显著正相关,与毛管孔隙度、非毛管孔隙度呈显著或极显著正相关,与土壤容重呈极显著负相关。[结论]在今后兰州市南北两山植被重建过程中,应营造不同树种所组成的混交林人工植被,不宜大面积营造人工纯林植被类型。

[Objective]The improvement degree of soil permeability in the artificial pure forest and mixed forest with different tree species conposition during the growth process was investigated,in order to provide a scientific basis for the selection of tree species during forest construction and during the tending and management of existing tree stands in this area.[Methods]Soil infiltration characteristics based on the double ring infiltration method,including initial infiltration,stable infiltration,average infiltration,and accumulative water quantity,were studied under five different forest types that included Platycladus orientalis,Populus alba var pyramidalis,Robinia pseudoacacia,P.orientalis+R.pseudoacacia,and P.alba var pyramidalis+R.pseudoacacia in the southern and northern mountains of Lanzhou City,Gansu Province.[Results]Soil infiltration characteristics decreased with increasing soil depth in the 0—80 cm soil layer.Soil infiltration characteristics under different forest types followed the order of P.alba var pyramidalis+R.pseudoacacia>P.orientalis+R.pseudoacacia>R.pseudoacacia>P.orientalis>P.alba var pyramidalis,indicating that infiltration characteristics of mixed forests were better than those of pure forests.A common empirical infiltration model provided the best estimates of infiltration processes for the five forest types,followed by the Horton,the Philip,and the Kostiakov models.Soil infiltration characteristics had extremely significant positive correlations with soil water content,total porosity,soil organic matter,soil total nitrogen,and mineral nitrogen.Additionally,soil infiltration characteristics had significant positive correlations with capillary porosity,and noncapillary porosity,and had significant negative correlations with soil bulk density.[Conclusion]These research results would be useful for providing a theoretical basis for the selection of tree species in the construction of artificial forests in the northern and southern mountains of Lanzhou City.