亚热带森林土壤微生物多样性的植物-土壤反馈机制研究

Soil microbial communities play a critical role in controlling plant species co-existence, community dynamics and diversity maintenance. Study on interactions between aboveground and belowground community is necessary to fully understand energy flow and nutrient cycling in terrestrial ecosystems. However, we know little about it, especially those in subtropical forests with rapid biodiversity loss. Plant–soil feedbacks are plant–induced changes in soil biotic and abiotic properties that in turn influence performance of the same or other plant species, which draws wide attention in recent years. The aim of our study is just to investigate the role of soil microbial diversity in plant-soil feedback, which is one of the key scientific questions so far. Specifically, our study would take advantage of an existing long-term platform that focused on biodiversity and ecosystem function and were established in 2008 in southern China, with a large data set accumulated on a natural forest succession series across different trophic levels. Based on the platform, we would like to test two hypotheses that: 1) plant diversity would stimulate soil microbial diversity due to resource complemetarity; 2) increased microbial diversity in soils would enhance nutrient availability and consequently increase plant growth.

土壤微生物对于陆地生态系统功能的维系至关重要，其在影响植物物种共存、群落动态和多样性维持等方面的研究更是成为最近二十年生态学研究的热点内容。其中，植物-土壤反馈研究是探讨植物与土壤生物互作关系的热点研究方向，亦是揭示土壤微生物多样性对地上植物生长和群落动态作用机制的有效手段。本项目关键科学问题正是探讨亚热带森林土壤微生物多样性在植物-土壤反馈过程中的作用，也是目前生态学相关领域广为关注的研究热点问题之一。具体而言，本项研究将依托中国-德国-瑞士国际合作共建的江西婺源亚热带森林生物多样性长期控制实验平台，通过高通量测序分析土壤真菌和细菌多样性对植物多样性变化的响应格局，通过盆栽控制实验探讨受到植物多样性调控的土壤微生物群落对植物生长的反馈调节机制，系统性地研究我国亚热带森林植物与土壤微生物的互作关系。

本项研究基于全球物种库最大的江西森林生物多样性实验平台，通过样地调查和盆栽控制实验探索亚热带森林植物多样性对地表和土壤微生物、尤其是真菌多样性格局的作用机制，并由此探讨受到植物多样性影响的微生物群落对植物生长的反馈调节。依托该项目拟解决的关键科学问题包括：1）验证“植物多样性假说”，即亚热带森林植物多样性增加促进地下微生物多样性？2）是否越高的植物多样性，其对应分解者类群及其过程正向的反馈调节作用越强？3）探讨植物多样性诱导的病原微生物的稀释作用是否会对特定物种生长形成正向反馈？样地实验研究发现植物多样性与地表和土壤微生物群落组成而非其多样性密切相关，说明植物群落多样性在调控微生物群落组成的重要性；同时发现植物多样性对微生物群落的影响存在明显的物种依赖性；不仅如此，邻居树种多样性和组成同样作用于目标树种个体林冠下微生物的群落多样性和组成。植物-土壤反馈盆栽控制实验研究发现土壤共生和病源真菌类群在调控目标树种个体生长过程中存在明显的互作关系，是驱动相邻树种共存的重要机制之一。