Lunch seminar "Fungal communities and their functioning in the Arctic-Boreal transition"

The warming climate is shifting forest northwards into the arctic tundra, which is currently storing a large proportion of the global soil C stock. The biotic feed-backs from tundra ecosystems to future climatic changes are highly uncertain. In a recent study we hypothesized that increasing abundance of shrubs and trees along the tundra-to-forest ecotone would be linked to increasing abundance of symbiotic ectomycorrhizal fungi and consequently decreasing stocks of soil carbon, due to more efficient recycling of organic matter. We combined high-throughput pyrosequencing to characterize fungal communities with ecosystem level measurements, such as C, N and stable isotope pools and biomass estimates. Our results clearly suggest that birch forest expansion into the Scandinavian heath tundra would shift the main C storage from soil to tree stems - and the relative importance of saprotrophic versus mycorrhizal fungi for this shift will be up for discussion.