Background and aims <p>Soil microbial communities, including fungi, play a pivotal role in the sustainability of forest ecosystems, yet the ecological processes driving their assembly with forest development remain elusive. This study aims to investigate the variations in the assembly mechanism of soil fungal communities with the development of <i>Torreya grandis</i> forests.</p> Method <p>Barcode sequencing was conducted to identify and characterize the fungal community in both bulk soil and the rhizosphere of <i>T. grandis</i> along a chronosequence spanning 900&#xa0;years in a subtropical forest. The total carbon, nitrogen and phosphorus contents of plant tissues, as well as major abiotic properties of the bulk soils, were determined simultaneously.</p> Results <p>Our findings reveal that fungal community composition, rather than alpha diversity, changes with stand development, independent of shifts in plant and soil properties. As stands develop, saprotrophic fungi become enriched and fungal co-occurrence networks simplify, particularly in the bulk soil, indicating a soil environment with reduced competitive pressure for niches among fungal populations. Fungal community assembly in bulk soils is governed by dispersal limitation, whereas that of the rhizospheric assemblage transitions from dispersal limitation to homogeneous selection as stands develop. Notably, the genus <i>Talaromyces</i>, known for its biocontrol and plant-growth promotion capabilities, dominates the ecological process transition in the rhizosphere of <i>T. grandis</i>.</p> Conclusion <p>Our results propose a host-mediated deterministic selection of beneficial fungal populations in the rhizosphere as stands develop, supporting the health and ecological sustainability of ancient forest ecosystems in subtropical areas.</p>