Objectives This study aimed to elucidate the structural differentiation and environmental determinants of ectomycorrhizal (ECM) fungal communities in Larix principis-rupprechtii plantations at different stand ages in the Daqingshan Mountains of northern China.

Methods Ectomycorrhizal fungal communities were characterized using Illumina MiSeq high-throughput sequencing. Community diversity, including taxonomic and phylogenetic diversity, was quantified, and multivariate statistical analyses were employed to identify key environmental drivers in relation to soil physicochemical properties.

Results Basidiomycota consistently dominated the ECM community across all stand ages, yet dominant taxa shifted along the chronosequence: Tricholoma was enriched in young stands; Wilcoxina and Amphinema were significantly enriched in mature stands; while Tricholoma re-emerged as the dominant genus in mature degraded stands. Species diversity exhibited a “rise-then-decline” trend, with mature stands showing the highest species richness, Chao, Shannon, and phylogenetic diversity (PD), and degraded stands showing the lowest. β-diversity and ordination analyses indicated clear separation among the three stand ages and strong species turnover, reflecting the combined effects of niche differentiation and environmental filtering during succession. Network analyses further demonstrated that mature stands exhibited higher node degree and modularity, suggesting greater potential functional redundancy and enhanced structural stability. Environmental interpretation identified soil pH and total phosphorus (TP) as the principal controlling factors: pH generally exerted a negative effect on diversity, while TP was positively associated with community composition and phylogenetic breadth. These results highlight the coupled regulation pf soil acidity and phosphorus availability was a key regulatory mechanism governing ECM fungal assembly.

Conclusion Stand age reshapes soil pH and phosphorus availability, driving age-related shifts and stage-specific enrichment of ECM fungal taxa along the successional gradient. The mature stage represents a critical window with maximal phylogenetic breadth and network stability for sustaining plantation ecosystem functions. From a management perspective, threshold-based soil amelioration and phosphorus regulation focusing on pH and TP, together with monitoring of phylogenetic diversity and indicator taxa, are recommended to enhance productivity, nutrient cycling, and carbon sequestration. For degraded stands, priority should be given to restoring microenvironmental conditions and soil nutrient availability to recover network complexity and functional redundancy.