贡嘎山暗针叶林土壤优先流形成因素的初步研究

该研究以长江上游贡嘎山暗针叶林生态系统的降雨过程、地被物层、根系层及土壤层的生长发育特点和水分运动状况为基础,利用自制实验仪器,在研究区域开展室内土柱实验,与野外实地示踪影像分析及树种根系调查相结合,针对研究区域土壤包气带根系层中水分快速运动的优先流形成的内外影响因子展开研究工作。研究结果表明研究区域土壤松散和多孔,土壤的孔隙度较大,大部分降雨为低强度、低雨量级和长历时,并具有较厚的地被物层和丰富的根系层,这些诱发因素存在,使研究区域——贡嘎山高山生态系统具有优先流形成的条件,降雨不会对土壤造成击溅作用,水分运移沿着土壤孔隙或植物根孔等处开辟优先路径,在地被物层及土壤层形成一个水流通道,随着长历时的降雨的继续,水分及其所携带的溶质继续沿着此路径向下运移。

STUDY OF SOIL PREFERENTIAL FLOW IN THE DARK CONIFEROUS FOREST OF GONGGA MOUNTAIN, CHINA

Background and Aims Preferential flow is the physical phenomenon of rapid transport of water and solutes in soil. It occurs in most soils and determines field-scale transport of contaminants in soils,thereby contributing to groundwater pollution. Methods Research on preferential flow involves studying the mechanism of soil water movement and can answer key questions that could not be explained by Darcy's law and Convective-Diffusive Equation in early hydrological research. Experimental or technological analyses are difficult because this movement is not detected easily. Preferential flow increases the difficulty and complexity of the research due to non-equilibrium,regional characteristics and the involvement of many influencing factors. To date,the mechanism of the movement of preferential flow has not been properly defined. This study involved detailed research on the influencing factors of preferential flow,using a soil column experiment in combination with dye-tracer analyzes in the root zone of the dark coniferous ecosystem in the upper drainage of the Yangtze River. Factors examined included rainfall processes,growth characteristics and water movement states of litter,moss,roots and soil. Key Results The soil of the research area is porous with large pores,and rainfall is low in amount and intensity and long-lasting. The soil also has thick litter and moss and is rich in roots. Therefore,the Gongga Mountain ecosystem may have preferential flow. Water transport has opened up preferential flow pathways along soil pores and root channels,forming a water channel in litter,moss and soil. Conclusions Soil will be transported continuously along these channels with longtime rainfall.