中文摘要：

外生菌根（ectomycorrhiza,ECM）是由土壤真菌与陆地植物根系形成的一种互惠共生体。ECM真菌从寄主植物中获取生长所需的碳源,同时促进寄主吸收氮、磷等矿物营养物质和水分。作为生态系统的重要组分,ECM真菌在生态系统的演替和多样性维持中发挥着重要的作用,因而揭示ECM真菌多样性的分布格局与维持机制是生物多样性与生态系统功能研究的热点领域之一。本文对ECM真菌多样性的最新研究进展进行了综合分析,相关研究显示,从热带到亚热带、温带森林,每种寄主植物上ECM真菌的平均物种数逐渐升高。扩散和选择过程都影响ECM真菌的分布格局,其中扩散对ECM真菌分布的影响具有空间尺度依赖性,即在全球和局域尺度上,扩散对ECM真菌分布的影响较弱,而在区域和小尺度上很强。同时,在局域尺度上,扩散对ECM真菌的分布具有寄主植物优势度依赖性,即在寄主植物不占优势的生态系统中,扩散对ECM真菌的分布有明显作用;而在寄主植物占优势的生态系统中则无影响。植物、动物、微生物和非生物因素的选择也都影响ECM真菌的分布格局,其中在温带地区所有研究均表明选择对ECM真菌的分布有影响,但是在热带地区有的研究表明选择对ECM真菌的分布有影响,而有的研究则显示无影响。植物的多样性和生产力都能影响ECM真菌的多样性,其中在温带、亚热带和热带森林中寄主植物属的多样性决定ECM真菌多样性,而植物生产力多样性假说只在一些温带的研究中得到证实。未来的研究重点应关注全球尺度,特别是在全球气候变化背景下的ECM真菌多样性的分布格局、维持机制及其生态系统功能等方面。

英文摘要：

Ectomycorrhiza （ECM） are symbionts formed between soil fungi and plant root systems, in which the fungus exchanges soil-derived nutrients for carbohydrates obtained from the host plant. As an important component of terrestrial ecosystems, ECM fungi can play an essential role in biodiversity maintenance and plant community succession. Understanding the distribution pattern and maintenance of ECM fungal diver- sity is therefore critical to the study of biodiversity and ecosystem functioning. An analysis of results of re- cent research indicates that ECM fungal diversity increases with increasing latitude, i.e. from tropical to sub- tropical and temperate regions. The role of dispersal in ECM fungal distribution is dependent on spatial scale. Thus, it has been found to be weak across global and local scales, but strong at regional and small scales. At the local scale, its influence has also been shown to be host-dominant dependent; thus, it is important in host non-dominant ecosystems, but not in host dominant ecosystems. Selection by plant, animal, microbe and abiotic factors can also affect the distribution pattern of ECM fungi, according to studies of temperate eco- systems. In contrast, studies of tropical ecosystems indicate that selection on ECM fungal distribution can be either strong or weak. ECM fungal diversity is also influenced by plant diversity and productivity. The plant diversity hypothesis at host genus-level fits well with ECM fungal diversity in temperate, subtropical and tropical forest ecosystems; in contrast, the productivity diversity hypothesis is only supported by some stud- ies in temperate forest ecosystems. We propose that future studies should focus on the distribution pattern, maintenance mechanism and ecosystem function of ECM fungal diversity at a global scale, taking account of scenarios of global climate change.