Impacts of competition on plant-mycorrhizal associations in a warmer Arctic

Global warming is occurring rapidly in the Arctic where a large portion of the global soil carbon pool is stored and where plant growth is nitrogen limited. Arctic woody shrubs and trees that associate with ectomycorrhizal fungi are already responding to current warming.

While this plant-ectomycorrhizal symbioses is often described as mutualistic whereby plants transfer carbon to the fungi in exchange for nutrients and water we know today that this description is too simplistic.

But mechanisms that govern the amount of carbon and nutrients exchanged in arctic plant-ectomycorrhizal associations are largely unknown.

Unravelling these mechanisms is important since ectomycorrhizal fungi can promote carbon storage by providing woody species with nutrients but at the same time may reduce soil carbon sequestration.

This project will test the role of an overlooked mechanism in this context: the competitive interactions among plants which often increase with a more favorable climate. It will run 2021-2024 and explore how warming and neighboring plants affect plant-ectomycorrhizal relationships.

It will use warming crossed with neighboring plant removal experiments in the greenhouse and along natural climate gradients to measure 1) carbon and nitrogen transfer in plant-ectomycorrhizal associations by dual labelling (15N and 13CO2) and 2) the consequences of a variation in carbon and nitrogen transfer in plant-ectomycorrhizal symbiosis for Arctic ecosystem C pools and fluxes.