杨树人工林丛枝菌根真菌群落对氮沉降的响应及其对土壤有机碳的影响机制

Increased nitrogen deposition is an element of global change that could influence the biodiversity. Arbuscular mycorrhizal fungi (AMF), a phylum of obligate biotrophic plant symbionts that are associated with the majority of land plants, play important roles in plant nutrient uptake and soil nutrient cycles. High atmospheric N deposition has been reported in forest ecosystems in central and east China. However, the impact of nitrogen depositions on arbuscular mycorrhizal community and the relationships between AMF and soil organic carbon storage are still not clear. The proposed research is to be conducted in Dongtai poplar plantation, northern Jiangsu province. Five gradients of nitrogen will be added in order to study the impacts of elevated N availability on arbuscular mycorrhizal fungi (AMF). Two main themes will be proposed. The first is to evaluate seasonal variations of plant-AM symbionts and AM fungal diversity and their key affecting factors after different levels of nitrogen additions based on field experiment. The second theme is to explore the mutual effects of AMF structures and fungal residues on soil carbon storage in different treatments. The fruits of the research will be expected to benefit the research of soil nutrient cycling and carbon sequestration for plantation ecosystem under the background of global change.

氮沉降增加是人类面临的全球性问题之一，其对森林土壤碳库的影响效应和影响机制尚不明确。丛枝菌根真菌结构、分泌物及其残留物对森林土壤有机碳库具有重要贡献。本项目拟以江苏省盐城市东台林场杨树人工林为研究对象，添加5种氮水平模拟氮沉降，利用高通量测序等技术，分析杨树根系-丛枝菌根真菌（Arbuscular mycorrhizal fungi, AMF）共生关系和土壤AMF群落结构，阐明氮添加条件下根系和土壤中AMF群落的变化特征及其关键控制因素，明确氮沉降对AMF群落的影响程度；采用生物标志物技术，明确AMF菌丝和分泌物对土壤有机碳库的贡献，解析土壤生物标志物与AMF结构和群落组成的耦合关系，揭示氮沉降影响土壤有机碳库的微生物机制。研究结果将为深入了解氮沉降增加背景下杨树人工林养分循环、碳固存和维持生态系统可持续发展提供基础资料和科学依据。

氮沉降增加是人类面临的全球性问题之一，氮沉降增加导致的土壤氮素含量变化，将对植物-丛枝菌根真菌（AMF）共生体产生影响。本项目围绕氮沉降对杨树人工林AMF群落及土壤有机碳库的影响展开，重点研究了：（1）模拟氮沉降对杨树根系-AMF共生关系的影响；（2）模拟氮沉降对杨树人工林土壤微生物群落和AMF群落的影响；（3）不同氮沉降水平下AMF 分泌物和残留物对土壤碳库的调控效应。研究工作围绕项目计划任务书内容展开，已达成预期目标。共发表学术论文5篇，其中SCI收录论文2篇，CSCD收录论文3篇；培养硕士研究生1名。主要进展如下：（1）利用传统染色法，测定了不同氮沉降水平下杨树人工林根系-AMF共生关系的季节动态，氮处理、树龄、季节对杨树根系-AMF侵染率有显著影响（P＜0.001）；（2）利用PLFA和高通量测序技术，测定了不同氮沉降条件下杨树人工林土壤微生物群落和AMF群落组成和多样性的季节动态，并分析了8个环境因子对微生物和AMF群落结构差异的贡献分别达到26.8%和33.0%，其中全氮、铵态氮和硝态氮均与群落结构组成有显著相关关系（P＜0.05）；（3）阐明了不同氮沉降水平下AMF分泌物和微生物残留物的季节动态，为揭示氮沉降影响土壤有机碳的微生物机制提供了科学依据。研究结果将为深入了解氮沉降增加背景下杨树人工林养分循环、碳固存和维持生态系统可持续发展提供基础资料和科学依据。