植物根孔构型与土壤优先流过程研究进展

A review of researches on plant root channel architecture and soil preferential flow process

植物根孔增加大孔隙网络的密度和连通性,促进土壤优先流发生。然而根孔在土壤中分布的构型特征复杂,揭示根孔构型特征影响土壤优先流过程的内在机制,对水资源高效管理、降低地下水污染和滑坡、泥石流等灾害风险具有重要意义。因此,笔者通过Web of Science和中国知网等数据库,检索获取截至2020年的相关研究文献,主要综述根孔构型的影响因素、量化方法及其对土壤优先流影响的研究进展,发现植物种类、年限季节、土壤属性等均会改变根孔的构型特征,但各因素的作用机制仍不清楚;CT扫描成像技术是量化根孔构型特征的有效方法;通过大孔隙阻断方法,能实地量化土壤入渗过程中优先流过程和基质入渗过程;植物根孔有效改良土壤入渗性能,土壤优先流通量与根孔数量、直径、表面积和体积等二维参数呈正相关关系。今后应深入研究根孔发育机制及其构型特征。加强根孔构型对土壤优先流过程的影响及作用机制的研究,是深入揭示土壤优先流运动机理的重要方向。

[Background]Root channels formed by the alive roots and rotten roots play an important role in increasing preferential flow and altering hydrological processes such as soil infiltration.The root channel architecture characteristics are very complex and difficult to describe accurately and quantitatively.The influence mechanisms of root channels on preferential flow infiltration process are theoretically beneficial to water resources management,groundwater pollution,landslides and mudslides prevention.[Methods]In view of this research hotspot,numerous literature retrieval were carried out with“root channels”“architecture characteristics”“preferential flow”“matrix infiltration”“soil infiltration”and“soil moisture”as keywords in the Web of Science and China National Knowledge Infrastructure(CNKI)databases.These keywords appeared very frequently in relevant fields.Representative literatures were selected for analysis and integration in the previous studies by the end of 2020.The influencing factors,quantitative measurement methods of plant root channel architecture were in detailed described,and the influences of root channel architecture on soil preferential flow infiltration process were discussed.[Results]1)The biological and abiotic factors,such as plant species,planting time,soil properties,and management measures significantly influence root channel architecture and the mechanism of each influencing factor are still unclear.In the past,due to technical methods and other limitations,soil macropores from different sources were often studied together during the study of preferential flow,without separately considering the characteristics of plant root channels and their importance.2)In recent years,it has become a trend to use CT scanning imaging technology to obtain three-dimensional parameters of root channel architecture,which can characterize the network structure of large pores from different sources(biopores and non-biopores)as a whole.3)Preferential flow and soil matrix infiltration are the two forms of soil water infiltration.During soil infiltration process,preferential flow must be accompanied by soil matrix infiltration.Previous quantitative research methods of preferential flow cannot quantitatively partition the temporal preferential flow and matrix infiltration,resulting in very little quantitative research of preferential flow infiltration process.However,the macropore connectivity blocking method provide a practical solution for quantitatively partition the temporal preferential flow and soil matrix infiltration.4)Plant root system may improve soil infiltration properties by forming root channels through its own decay and decomposition.The values of root channel numbers,area,volume,and diameter are significantly and positively correlated with the soil infiltration rates and preferential flow flux.[Conclusions]Therefore,in the future,the three-dimensional quantitative index system for root channel architecture should be established to reveal development mechanism and architecture characteristics of plant root channel.More efforts should be focused on the influence mechanisms of root channel architecture on soil preferential flow infiltration process.It will be an important research direction to deeply reveal the mechanism of soil preferential flow movement and its contribution to water infiltration.