The mycorrhizal status of the dominant vegetation along a peatland gradient in southern boreal Alberta, Canada

We investigated the mycorrhizal status of the dominant vascular plant species occurring in ten peatlands along a bog—fen—marsh gradient in southern boreal Alberta in 1997. All members of the Ericaceae were ericoid mycorrhizal, and members of the Salicaceae and Pinaceae were ectomycorrhizal. Also, some members of the Salicaceae and Betulaceae were simultancously ecto- and vesicular-arbuscular mycorrhizal (VAM). Fruiting bodies of the known ectomycorrhizal fungal generaCortinarius, Lactarius, andRussula were collected in late fall. Furthermore, the cosmopolitan ectomycorrhizal taxonCenococcum geophilum was associated with trees and shrubs in all fens and bogs. VA-mycorrhizal fungi were not found in any of the dominant herbaceous plant species in these peatlands; however, vesicles suggesting the presence of VAM fungi were found inCalamagrostis canadensis in the riverine marsh andRubus chamaemorus in the bog. NeitherCarex species in fens and marshes, norTypha latifolia in the lacustrine marsh were mycorrhizal; however, microsclerotia, sclerotial plaques, septate, aseptate, and clamped hyphae were observed to grow on and within cortical cells of their roots. Many of these hyphae were dematiaceous and may belong to theMycelium radicis atrovirens complex (MRA), partially consisting of the endophytic fungal generaPhialocephala andLeptodontidium. Hyphac resemblingRhizoctonia were also observed, although definitive identifications were not attempted. The ecological significance of MRA genera remains largely unknown. Thus, the dominant vegetation in southern boreal bogs and fens is mycorrhizal, possibly enabling these plant species to proliferate in these nutrient-poor ecosystems by accessing otherwise unavailable nutrient pools. In contrast, marsh vegetation is generally non-mycorrhizal, possibly due to higher surface-water nutrient concentrations and fluctuating water levels.