土壤微生物多样性对氮磷养分添加响应及与生态系统功能关系

Microbial diversity plays critical roles in regulating multiple ecosystem functions and enhancing ecosystem stability. Enhanced nitrogen (N) deposition may accelerate phosphorus (P) deficiency; thereby influence biogeochemical processes and functions of forest ecosystems. However, little information is available on how P addition would affect soil microbial community and genes diversity, and how it would interact with N deposition. Meanwhile, it is unclear how NP additions affect relationships between microbial diversity and ecosystem function. In this study, based on three controlled NP additions filed experiments along the North-South transect in eastern China , we investigated soil microbial community and genes diversity by using genome techniques including high-throughput gene sequencing and Geochip . Specifically, we established the functional group network of soil microbes that are responsible for soil C、N and P cycling. We also identified the major environmental factors that shaping microbial community and genes diversity, and quantitatively assessed the relative importance of changes of microbial diversity in influencing specific ecosystem functioning and multifunctionality (considering multiple ecosystems functions simultaneously). This study would contribute to a deeper understanding on the role of microbial diversity in biogeochemical cycling processes under influences of more N and P additions in regional representative forest ecosystems. Meanwhile, it also provides theoretical basis for promoting the sustainable development of forest ecosystems and strengthening the management and functional regulation of forest ecosystems.

土壤微生物多样性在维持陆地生态系统功能和稳定性方面起着关键作用。氮（N）沉降的持续增加促使生态系统由N限制转变为磷（P）限制，进而影响森林生态系统过程和功能。遗憾的是，有关P添加以及NP交互作用对森林土壤微生物多样性影响、驱动机制及与生态系统功能之间的关联性方面研究还十分薄弱。本项目依托于中国东部南北样带上3个NP养分添加实验平台，利用高通量测序和基因芯片等基因组学技术，研究土壤微生物群落和功能基因多样性对NP养分添加响应；构建介导C、N和P循环过程的微生物功能群网络；识别影响微生物多样性的主控环境因子；量化NP养分添加引起的微生物多样性改变对单一生态系统功能及生态系统多功能性的影响。研究结果对深入理解未来NP养分输入增加下区域代表性森林生态系统土壤微生物多样性在生态系统生物化学循环过程中的调控机理具有重要科学意义，同时也为加强森林生态系统管理和功能调控提供重要科学依据。

土壤微生物多样性在维持陆地生态系统功能和稳定性方面起着关键作用。本项目依托于中国东部南北样带上3个NP养分添加实验平台，利用高通量测序和基因芯片等基因组学技术，研究了土壤微生物群落和功能基因多样性对养分添加响应；构建了介导C、N和P循环过程的微生物功能群网络；量化NP养分添加引起的微生物多样性改变对单一生态系统功能及生态系统多功能性的影响。我们的研究发现在热带森林生态系统（鼎湖山），单独施P显著影响土壤细菌群落，且显著区别于施N以及NP处理。而在温带森林生态系统（长白山），土壤细菌群落在单独N添加处理显著区别于其他处理。与不施肥相比，N肥添加处理细菌网络复杂度降低，而NP和单独施P处理网络复杂度增加，并且施肥后细菌之间互惠关系作用降低，但是细菌功能模块数量增加。在温带生态系统，N添加降低了R/K策略微生物的相对丰度，进而增加了土壤未保护性碳库，化学和生物化学碳库。在热带系统，N添加降低了细菌生物量以及C功能基因的表达量，进而降低了土壤CO2含量，促进了土壤SOC积累。温带森林生态系统，N添加相比P和NP添加具有更高的生态系统多功能性以及碳循环功能和氮循环功能指数。在热带系统，P添加则显著提高了生态系统P循环功能指数。不同系统中，优势微生物物种对生态系统多功能性，以及C, N和P功能均具有重要作用。研究结果对深入理解未来NP养分输入增加下区域代表性森林生态系统土壤微生物多样性在生态系统生物化学循环过程中的调控机理具有重要科学意义，同时也为加强森林生态系统管理和功能调控提供重要科学依据。