Arbuscular mycorrhizal distribution in relation to microsites on recent volcanic substrates of Mt. Koma, Hokkaido, Japan.

Mycorrhizae occur in most terrestrial ecosystems and are crucial to understanding community structure and function. However, their role in primary succession is poorly understood. This study examined the mycorrhizal colonization of six plant species in relation to microsite types on recent volcanic substrates on the summit of Mt. Koma, Hokkaido, Japan. The six microsites were flat, rill, near rock, Carextussock, Polygonum patch and Salix patch. Carex oxyandra was nonmycorrhizal and Agrostis scabra and Campanula lasiocarpa were arbuscular mycorrhizal (AM) at all microsites examined. Agrostis AM colonization levels did not differ across microsites. Near rock Campanula roots contained significantly more hyphae than at flat and Polygonum patch microsites, and rill and Carex tussock Campanula more arbuscules than at Polygonum patches. Penstemon frutescens was found to be facultatively mycotrophic with AM colonization occurring in roots of Penstemon growing in Carex tussocks, Polygonum patches and near rocks. Polygonum weyrichii was found to be ectomycorrhizal. Polygonum located in rills and in Polygonum and Salix patches were more colonized than Polygonum in Carex patches. Salix reinii was heavily ectomycorrhizal.