Mycorrhizae are fundamental and ubiquitous fungi in association with most of land plants, representing a massive underground fungal network interacting with an innumerable number of organisms. Belowground mycorrhizal structures represent consequently a significant amount of soil organic matter and biomass in many ecosystems. Indeed, mycorrhizal fungi have been found to colonize 80-90% of the roots of vascular plant species, conferring to their host nutrient uptake advantages, protection against root and leaf pathogens, as well as drought, salt, and toxicity tolerance. Scientists have dedicated much effort to estimate fungal diversity and identify new species, but we still ignore much about the fungal world. Yet, these highly complex and diverse organisms play key roles in ecosystem processes (e.g., plant productivity, nutrient cycling, decomposition, carbon dynamics) and services (e.g., soil fertility and aggregation, crop quality, production, restauration). In a world where climate change became one of the biggest threats of our era, studying mycorrhizal associations is crucial for biodiversity conservation, ecosystem integrity, and agriculture sustainability. Additionally, since plants benefit greatly from these fungal symbionts, mycorrhizal fungi are foreseen to play a critical role in plant establishment in novel environments (e.g., plant naturalization, invasiveness, and migration) and the recovery of degraded terrestrial ecosystems. Therefore, the objective of this organized oral session (OOS) is to present the recent work and discoveries of ecologists studying the roles and functions of mycorrhizal fungi in regulating climate change in local (e.g., plant-microbe interactions) and global (e.g., ecosystem dynamics and plant biogeography) perspectives. Furthermore, this OOS covers research from fundamental to applied ecology to incorporate a full portrait of the importance of mycorrhizal associations within terrestrial ecosystems, as well as developing and promoting the latest theorical and technical insights of this field of study. To improve our understanding of the roles of mycorrhizae facing climate change, we draw from multidisciplinary expertise including ecology, genomics, microbiology, and bioinformatics. With our session, we hope to promote new findings on mycorrhizae, to highlight the importance of plant-fungi associations studies and to encourage collaborations that will lead to breakthroughs in this field of research.