"植物-土壤"相互反馈的关键生态学问题:格局、过程与机制

植物与土壤之间相互反馈的格局、过程与机制,不但是决定生态系统结构、功能及过程的关键科学问题,而且是陆地生态系统响应全球变化的重要组成部分。基于目前国内外研究现状,从养分循环角度剖析“植物-土壤”间的反馈效应,探明相互反馈在空间尺度(根面、根际、种类、生态系统以及区域等)与时间尺度(秒至千年)上的级联效应及其变化格局;阐明根际、植物种类、生态系统及区域地理等水平上“植物-土壤”的相互反馈机制,重点揭示根系分泌、共生、生长及代谢的根际界面过程对植物水分/养分吸收与土壤物理学修饰的调控机制,剖析“植物种类-凋落物化学-土壤生物-土壤有机质”相互作用对地上-地下养分循环过程的驱动机制,运用“上行-下行控制理论及腐屑食物网模型”揭示地上-地下生物群落交互作用的过程与机制,以及土壤地质演变(岩石风化模式、土壤形成模式及土壤养分格局的变化)与区域植被演替(优势种更替及植被分布模式、地上-地下凋落物输入格局等的变化)相互反馈的过程与机制;从“植物-土壤”相互反馈的理论视角,分析生态退化与恢复、外来物种生态入侵、大气氮沉降、二氧化碳浓度升高以及植物多样性减少等全球生态问题的特征、形成机制以及可能的应对策略,揭示生态系统“地上-地下”相互反馈的生态学过程,以及陆地生态系统对全球生态环境变化的响应特征与机理。

Key ecological issues in plant-soil feedback:pattern,process and mechanism

The process and mechanism of mutual feedback between plant and soil can determine the structure,function and process of ecosystems.They are also key scientific issues to understand the responses of terrestrial ecosystems to global changes.This review focused on cascading effects and their variations in patterns of nutrient-feedback between plant and soil at different spatial scales(i.e.,root surface,rhizosphere,species,ecosystem and region)and various temporal dimensions(from seconds to thousand years).The plant-soil feedback was expounded at the level of root-soil interface,plant species,ecosystem and regional geography.We highlighted the regulatory mechanism of rhizosphere-interface process of root secretion,symbiosis,growth and metabolism on soil water and nutrients absorption,and physical modification.Moreover,we expounded the mechanism of above-and under-ground nutrient cycling process driven by interactions among plant species,litter chemistry,soil organism and soil organic matter.The bottom-up and top-down control theories,and the detritus food-web model were applied to reveal the process and mechanism of interactions between above-and under-ground biotic communities.We explored the process and mechanism of mutual feedback between soil geography evolution(the change in pattern of rock weathering,soil formation and soil nutrients),and regional vegetation succession(i.e.,dominant species replacement,and shifting in mode of vegetation distribution,and above-ground litter input).This review also focused on the characteristics,formation mechanism and possible regulatory strategies of plant-soil mutual feedback for global change issues(i.e.,ecological degradation and restoration,ecological invasion of alien species,atmospheric N deposition,elevated CO2 concentration,and reduced biodiversity).Furthermore,we concluded the biological and ecological processes of the interactions between above-and under-ground terrestrial ecosystems,predicting the response characteristics and mechanism of terrestrial ecosystems.