Objective This study aimed to investigate the variation characteristics of root soil physicochemical properties, fungal community structure, and soil metabolite composition in Pinus tabuliformis under different levels of damage, to reveal the response patterns of the root microecology of P. tabuliformis to infestation by Dendroctonus valens, and to provide a scientific basis for developing green control strategies against D. valens based on root microecological regulation.

Method Healthy, mildly, moderately, and severely infested P. tabuliformis trees were selected as sampling subjects. Root soil physicochemical properties were measured; fungal community composition and diversity were analyzed using high-throughput sequencing; soil metabolic profiles were characterized by liquid chromatography–mass spectrometry.

Result (1) With the aggravation of the infestation, the soil exhibited an acidification trend, and the available phosphorus content is highest at the mild and moderate hazard stage, and declined at the severe hazard stage. (2) Fungal community richness and diversity increased significantly at the severe hazard stage, and the community structure changed markedly; the dominant taxa gradually shifted from ectomycorrhizal fungi such as Russula spp. to saprophytic fungi such as Penicillium spp. (3) Root soil metabolites composition changed markedly, and defense-related metabolites, including fatty acid derivatives, diterpenoids, and phenylpropanoids, were significantly enriched under moderate and severe infestation. (4) Significant correlations were detected between root soil metabolites and fungal community structure. Ectomycorrhizal fungi were positively correlated with plant growth hormones, whereas saprotrophic and pathogenic fungi were positively correlated with resin acids and abscisic acid-related metabolites.

Conclusion This study demonstrates that infestation by D. valens triggers stage-specific responses of the root microecosystem in P. tabuliformis by altering soil physicochemical properties, reshaping fungal community structure, and modulating root defense metabolism. These findings enhance our understanding of plant–soil–microbe coordinated defense mechanisms under insect stress and provide a theoretical foundation for the development of root microecology-based green management strategies against D. valens.