Ectomycorrhizal fungal community varies across broadleaf species and developmental stages.

Ectomycorrhizal fungi (EMF) play pivotal roles in determining temperate forest ecosystem processes. We tracked root EMF community succession across saplings, juveniles, and adults of three temperate broadleaf trees (Acer mono, Betula platyphylla, and Quercus mongolica) in Northeast China. Adult stages showed higher alpha diversity but lower community dissimilarity compared to earlier stages. In particular, the EMF alpha diversity of Quercus mongolica marginally increased along with host developmental stages and ranked as sapling < juvenile < adult. Unlike those of Acer mono and Quercus mongolica, the EMF community composition of Betula platyphylla showed greater variation between the sapling and juvenile stages than between the sapling and adult stages. Cooccurrence networks revealed increasing interconnectivity with host maturity, dominated by positive correlations (> 99%). LEfSe was employed to identify stage- and/or host-specific EMF indicators. This study highlighted the assembly of EMF community during the development of broadleaf trees in temperate forests, thereby advancing understanding of the succession and coevolution of symbiotic relationships.