A recent study has shed light on how mycorrhizal fungi, which form symbiotic relationships with over 80% of tree species, shape the structure and diversity of temperate forests. Researchers from the Chinese Academy of Sciences’ Institute of Applied Ecology have discovered that the unique “ectomycorrhizal (EM) dominant vs. arbuscular mycorrhizal (AM) diverse” coexistence pattern in temperate forests may be driven by distinct stabilizing mechanisms in EM tree species.

While AM trees account for more than 70% of species diversity in these forests, they often exist as rare or non-dominant species. In contrast, EM trees represent only 4% of tree species but include key forest-forming species like pines and oaks (dominant species). Dr. Mao Zikun and Prof. WANG Xugao, the study’s lead authors, reviewed three hypotheses to explain this coexistence and unusual balance: the AM-stabilization hypothesis, the AM-EM complementarity hypothesis, and the EM-stabilization hypothesis. They tested these hypotheses using spatial point pattern analysis in two large-scale forest plots in Changbai Mountain.

The study’s findings support the “EM-stabilization” hypothesis, revealing that EM trees play a critical role in facilitating the coexistence of both tree types. In early growth stages, EM trees help stabilize AM and EM seedlings, forming clusters that resist pathogens and foster beneficial fungi. As EM trees mature, they compete for limited soil nutrients, which limits the abundance of nearby AM trees and reinforces the dominance of EM species. This two-stage stabilization process underpins the observed “EM dominant vs. AM diverse” coexistence model in temperate forests.

The researchers highlighted that EM trees act as “facilitation hotspots” that sustain species diversity. This research emphasizes the importance of preserving EM-dominant trees for the long-term resilience and sustainability of temperate forests.

These findings, published in Ecology Letters, could influence future forest conservation and management strategies.