Soil is a complex system comprised of a large number of belowground interactions between the living and non-living elements. Among these interactions, many plants and fungi have developed a close relationship that can be beneficial to both partners. The aim of this project is therefore to better understand the interactions between plants and their fungal partners in sugar maple ecosystems found in southern Quebec. Subsequently, a field experiment will allow us to highlight the effect of plants-fungi associations on organic matter decomposition. Finally, in the context of climate change, we will attempt to determine the extent to which the expected migration of trees such as maple from temperate to boreal forests will be impacted by microbes in boreal soils. As a whole, this project aims to improve our understanding of the role of underground interactions in the functioning of ecosystems.