Invasive ectomycorrhizal fungi: belowground insights from South America.

Ectomycorrhizal fungi (EMF) are essential for nutrient cycling and plant symbiosis, yet their invasions remain understudied, particularly in South America. Large-scale forestry introductions have spread non-native EMF across the continent. Although definitions vary, EMF are invasive when they disperse, colonize new environments, and overcome natural barriers. Invasive EMF alter soil biogeochemistry and local microbial and plant communities, sometimes preceding plant invasions. Despite their importance, invasive EMF remain poorly documented, with major knowledge gaps. Research must strengthen local networks, expand access to molecular tools, and integrate traditional knowledge. In turn, unregulated commercial inoculants pose risks, requiring policy intervention. South America offers a unique opportunity to strengthen collaboration and regional research to help elucidate and prevent future EMF invasions while guiding conservation.