增温与放牧对青藏高原高寒草甸丛枝菌根真菌群落结构的影响

Arbuscular mycorrhizal fungi (AMF), one of special and important soil microorganisms, are an important node linking aboveground ecosystem to belowground ecosystem. However, little is reported that the interactive influence of warming and grazing on AMF. Previous studies showed that experimental warming can result in plant species loss, but moderate grazing may offset the effect of warming on plant community. Then, how do the plant-associated AMF respond to warming and grazing? What do play a key role in driving the response of AMF to warming and grazing? What is the relationship between AMF and changing temperature? What is the relationship between plants, AMF and soil characteristics under the interactive treatments of warming and grazing? To answer the above questions, we plan to investigate how the gradient warming and grazing influence plant community, AMF and soil characteristics in alpine meadow ecosystem. We aim to elucidate the influences pattern of warming and simulated grazing on AMF and plant community, and illustrate the relationship between plant community, AMF and changing soil temperature. Our research will provide new insights for the sustainable managements and ecological restoration of alpine meadow ecosystem.

丛枝菌根（arbuscular mycorrhiza, AM）真菌是一类特殊且重要的土壤微生物，是地上地下生态系统相互联系的重要节点。但，目前增温与放牧对高寒草甸AM 真菌的影响机制仍不清楚。以前的研究发现，增温能够导致植物物种的丧失，而适度放牧缓解了由增温导致的植物多样性丧失。那么，与植物共生的AM真菌如何响应增温（温度改变）和放牧的？驱动AM真菌对气候变暖的响应关键因素是哪些？ AM真菌与温度变化之间关系如何？在增温与放牧双重处理下，植物-AM真菌-土壤环境间关系如何？ 针对上述问题，本项目依托中国科学院海北高寒草甸生态系统定位研究站，通过系统地研究梯度增温与放牧对植物、AM真菌与土壤环境的影响规律，旨在阐明高寒草甸植物群落与AM真菌对增温与放牧响应模式，揭示植物群落、根际AM真菌与温度变化间关系，为高寒草甸的可持续利用和退化草地的恢复提供生态学依据和技术支撑。

在自然生态系统中，丛枝菌根（Arbuscular mycorrhizal, AM）真菌参与了多个生态系统过程。然而，对于AM真菌群落是如何响应梯度增温与冬季刈割的目前仍不清楚。基于此，本研究设置了一个梯度增温与冬季刈割（以模拟冬季放牧的立枯体去除效应）的交互实验，旨在探究高寒草甸生态系统在有无刈割处理的条件下沿着一个增温梯度AM真菌群落的动态变化。本研究中通过使用454高通量测序的方法，共检测到63个AM真菌分子种。增温与刈割均降低了AM真菌物种丰富度，但二者无叠加的负效应。刈割、刈割与增温的交互作用均改变AM真菌群落的物种组成，但未能改变AM真菌群落的谱系组成。在无刈割处理下，随着温度的升高AM真菌群落的谱系结构发生了从谱系随机向谱系聚集的转变，但在刈割处理下所有AM真菌群落的谱系结构均为谱系随机，说明在无刈割处理下随着温度的增加驱动AM真菌群落组装的主要生态学过程由随机过程向环境过滤进行转变，但在刈割处理下无转变。该研究结果说明冬季刈割不仅改变了AM群落对增温响应模式，还改变了驱动AM真菌群落组装的主要生态学过程。该研究表明在全球气候逐渐变暖的背景下，冬季放牧的立枯体去除效应在调节土壤微生物多样性的维持中的重要作用。