植物碳输入变化对滇中湖群富磷区土壤磷素流失过程的影响

The phosphorus (P) transport from soil in phosphorus-enriched mountainous areas of central Yunnan to water body has become an important source of non-point source pollution in lake eutrophication. Plant-soil microbial system is the key component to prevent and control soil phosphorus loss. However, its operational mechanism is not clear. In order to deepen the understanding of the role of plant-microbial system and its mechanism in the control of soil P loss, effects of plant carbon inputs (litter input and belowground carbon allocation) and responded soil microbial communities on soil hydrological pathways and distributions of P fractions in soil and runoff will be taken as a breakthrough point to analyze the induced changes of soil P fractions, soil hydrological pathways, and P fluxes using the greenhouse experiments and field-experiments, and to investigate the relative role of responded soil microbial community in the process of soil P loss. On basis of that, the overall characteristics of soil P fraction–hydrological pathway-P loss and the main biohydrochemical processes in reducing soil P loss will be compared and discussed to reveal the mechanism of plant-soil microbial system on soil P cycling. This study will provide scientific evidence for plant selection and action mechanism in control of soil P loss, and also for control of non-point source pollution in phosphorus-enriched mountainous areas of central Yunnan and other similar areas.

滇中湖群区山地富磷土壤磷素的迁移入湖已成为湖泊面源污染的重要来源。植物-土壤微生物系统是源头上防控土壤磷素流失的关键环节，但其影响过程及机制还不明晰。本项目拟以植物碳输入及所引起的土壤微生物群落变化对土壤不同水文途径及其相应土壤-径流中磷素形态组分特征的影响作为切入点，通过野外控制及室内模拟试验，分析植物碳输入变化（地上凋落物输入及地下根系碳分配）对不同时空尺度上土壤磷素组分、土壤水文过程及其磷素流失特征的影响，并在此基础上量化植物碳输入所引起的土壤微生物群落在磷素流失过程中的相对作用，整合分析不同植物碳输入变化条件下土壤磷素组成-水文途径-磷素流失过程的总体特征，剖析植物在减控磷素流失过程中的主要生物水文化学过程，揭示滇中富磷区植物-微生物系统在土壤磷素循环过程中的作用机制，为该区域土壤磷素有效削减的植物选择及机制研究提供科学依据，也为高原湖泊及其他类似区域的面源污染防治提供科技支持。

滇中湖群区山地富磷土壤磷素的迁移入湖已成为湖泊面源污染的重要来源。植物碳输入条件下植物-微生物系统是源头上防控土壤磷素流失的关键环节。本研究通过野外控制及室内模拟试验，分析了不同植物碳输入方式对土壤磷素循环过程及其磷素流失特征的影响，并在此基础上量化了植物碳输入所引起的土壤微生物群落在磷素流失过程中的相对作用。结果表明富磷土壤中闭蓄态磷与中度活性磷是富磷区土壤的主要磷组分；而贫磷土壤闭蓄态磷和有机磷是贫磷区土壤磷素的主要组分，这说明生物过程及物化过程分别是贫磷区与富磷区磷素循环的主要控制过程；不同植物群落土壤磷素流失具有显著差异，磷流失总量呈荒草坡>云南松林>常绿阔叶林，磷流失与土壤理化性质、植物群落物属性密切相关。土壤微生物尤其是土壤丛枝菌群落在土壤磷素流失防控中具有重要作用，土壤丛枝菌群落可以通过改善土壤团聚体结构，提升土壤对原位磷素的截留效能，减少磷素的流失潜能。本项目结果揭示了滇中富磷区植物-微生物系统在土壤磷素循环过程中的作用过程，为该区域生态修复及湖泊富营养化防控研究提供了科学依据及技术支持。