Mycorrhizal networks: Understanding hidden complexity

The symbiotic relationship between mycorrhizal fungi and plants predates the origin of roots and has played a key role in shaping ecosystems for hundreds of millions of years. In associating with multiple plants simultaneously, mycorrhizal fungi can form complex below-ground networks that directly—and indirectly—influence plant communities, plant and soil resource dynamics, and broader ecosystem processes. Research has provided increasing insight into the structure and function of these networks, including the movement and exchange of resources between symbionts, the mechanisms governing fungal and plant community assembly, and their potential applications in land management. As public interest in mycorrhizal networks has grown, so too have calls within the scientific community for greater clarity regarding their ecological functionality and broader significance. This Special Focus brings together research that advances our understanding of these networks from multiple perspectives. Contributions explore the hierarchical complexity of fungal-plant associations, the ecological and functional implications of mycorrhizal selectivity, the resource exchange dynamics, and their relevance in applied contexts, such as agriculture. By synthesising emerging evidence, this collection highlights key advances while also identifying unresolved questions and the future research directions necessary for disentangling the ecological roles of mycorrhizal networks. Read the free Plain Language Summary for this article on the Journal blog.