城市菌根真菌多样性、变化机制及功能应用

Mycorrhizal fungi in urban environments: diversity,mechanism,and application

菌根真菌能够与大多数陆生植物的根系形成菌根共生体,具有改善宿主植物矿质营养、增强抗逆性、改良土壤结构等重要生态功能。城市化过程中气候、土壤、植被、土地利用等因素的改变,对菌根真菌的多样性产生了直接或间接的影响。目前城市菌根真菌的研究多侧重对其空间分布及群落组成的简单描述,缺乏针对城市典型生态现象及生态问题系统性的探讨。分别从城市菌根真菌的多样性变化、影响机制及功能应用等3方面进行了综述,全面揭示城市菌根真菌的研究现状及研究的复杂性,发现当前研究存在多样性评估简单化、研究层次单一化、内在机制现象化及功能应用停滞化等问题,认为今后应建立更为系统、综合、标准的研究体系以深刻而准确地认识与理解城市化对菌根真菌多样性的影响,为城市微生物资源的保存及绿地系统维持提供理论依据。

Mycorrhizal fungi colonize the roots of most terrestrial plants, facilitating mineral nutrient uptake, enhancing stress resistance, and improving soil structure. Although their functional importance is well recognized, they are often overlooked in urban ecological surveys. For instance, of 15685 papers referring to mycorrhizal research published from 1990 to 2014, only 106 papers （0.68%） are related to urban areas. In addition, most of these studies focused only on preliminary assessment of mycorrhizal fungal diversity and community structure; knowledge of how these fungi are affected by urbanization and the roles they play in urban ecosystems remains relatively rare. However, mycorrhizal fungi are sensitive to various biotic and abiotic factors, and it is well documented that urbanization usually reduces their abundance and species richness, and changes their community composition. Thus, mycorrhizal fungi, especially ectomycorrhizal fungi, have potential as bioindicators of the quality of urban green-space systems. Anthropogenic activities cause many local environmental problems such as biotic homogenization, soil degradation, and pollution. Coupled with human management of landscapes, a variety of properties of urban environments are identified that may affect the survival of mycorrhizal fungi. However, given the ecological complexity of urban ecosystems, their mechanisms of action are still largely unknown. This paper first reviews the changes in mycorrhizal fungal diversity in cities, and then highlights the ecological processes and factors that may potentially affect their persistence. The subsequent discussion focuses on potential ecological benefits from mycorrhizal mutualisms. Because of its positive effect on plant nutrition and soil structure, the application of mycorrhizal technology in damaged ecosystems has been advocated. Nevertheless, because clear and comprehensive findings from field research are lacking, this technology is not available for landscape management, a field beset with many uncertainties and assumptions. Despite its promise, little work has been done on this technology, and more research is needed in the future to develop practical approaches within the context of urban landscapes. In general, knowledge of mycorrhizal fungi in cities is somewhat limited, and it is often hindered by the complexity of urban environments. A more sophisticated, systematic, and standard framework of research is needed to assess the diversity of mycorrhizal fungi in urban habitats and to clarify the impact of urbanization on their distribution and assemblages, as well as to understand the broader implications of altered fungal communities. This is of great importance in microbial resource conservation and green-space maintenance in cities.