High species richness an dominance of Cortinarius taxa in belowground communities of ectomycorrhizal fungi from the Canadian Arctic.

 Anders Dahlberg¹ , Monique Gardes² and Jean-Yves Charcassot²,
¹Swedish University of Agricultural Sciences, SWEDEN,
²CESAC/CNRS Université Paul Sabatier/Toulouse FRANCE,

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In 1999, we participated to a a ship based research expedition to the Canadian arctic archipelago arranged by the Royal Swedish Academy of Sciences. The expedition, Tundra NorthWest 1999 (http://www.polar.kva.se), was focused on the tundra's ecology. Seventeen study sites were selected to represent a longitudinal and latitudinal gradient of the area and to encompass vegetation within the Low to High Arctic zones. We collected mycorrhizas
from the two most abundant and widely spread ectomycorrhizal plants in the Arctic: Salix arctica and Dryas integrifolia. PCR-based molecular methods were used to identify the mycobionts and to provide an assessment of diversity patterns at different spatial scales. The
mycobiont species richness was high, approaching that in boreal forest ecosystems. In total more than 130 taxa were encountered. Species of Cortinarius dominated, comprising
more than 20% of the abundance and constituted 4 of the 6 most frequently encountered taxa. Salix and Dryas to a large extent shared the same mycobiont taxa. The characteristics and tentative mechanisms shaping the Arctic ectomycorrhizal commmunities will be discussed and related to patterns found in forest ecosystems.