MYCORRHIZAL DIVERSITY IN ARCTIC AND ALPINE TUNDRA - AN OPEN QUESTION

Current knowledge of mycorrhizal diversity in arctic and alpine tundra is based mainly on static surveys of mycorrhizal associations of plan t taxa and fruiting patterns of selected ectomycorrhizal fungal specie s in specific habitats. Within these limitations, it appears that: (1) non-mycorrhizal plants are widespread and predominate in certain plan t communities; (2) typical arbuscular mycorrhizal associations are ubi quitous in low arctic and alpine areas but that the level of root colo nization is highly variable; (3) root colonization by dark septate fun gi is a common event but that their ecological significance is still u nknown; (4) a large number of ectomycorrhizal fungal species are prese nt as symbionts of a relatively few widely distributed shrubs and herb aceous plant taxa; (5) ericaceous plants with ericoid mycorrhizas domi nate large arctic and alpine areas covered by heath communities. Physi cal environmental features strongly limit and shape species diversity in arctic and alpine tundra. Cold-dominated environments provide extre me conditions for the establishment and functioning of mycorrhizal ass ociations. Therefore, such systems are simple models to address the ec ology and evolution of mycorrhizal symbioses. Molecular methods to ide ntify mycorrhizal fungi on plant rents will resolve questions related to the structure and dynamics of communities of mycorrhizal fungi in a rctic and alpine tundra.