Management cessation drives divergent bacterial and fungal community assembly in moso bamboo forests of the central Hunan hilly region, China.

Management cessation and subsequent abandonment alter soil resource availability and chemical conditions, yet how bacterial and fungal communities differ in their responses-in terms of diversity, community structure, and assembly processes-remains poorly resolved in moso bamboo forests. We sampled 27 composite soil samples from three soil depths (0-10, 10-20, and 20-30 cm) across three management regimes, including extensive management (EM), 10-year abandonment (AM10), and 20-year abandonment (AM20), in moso bamboo (Phyllostachys edulis) forests at Taohuajiang State Forest Farm, Taojiang County, Yiyang City, Hunan Province, China. 16S rRNA and ITS amplicon sequencing were combined with measurements of soil physicochemical properties and enzyme activities. Management cessation and subsequent abandonment were associated with distinct soil environmental gradients, especially in total K, pH, and ammonium nitrogen. Bacterial Shannon diversity declined monotonically with abandonment duration (EM > AM10 > AM20), while fungal diversity exhibited a significant treatment × depth interaction (F = 8.80, BH-adjusted P < 0.001), indicating that soil depth modulated fungal responses to abandonment. PERMANOVA explained 77.0% of bacterial community variation but only 34.4% of fungal variation. Assembly analyses revealed that bacterial communities shifted from dispersal limitation (91.7% in EM) toward homogeneous selection (52.8% in AM20), whereas fungi were predominantly governed by stochastic processes (drift or undominated, 75.2%). Bacterial and fungal communities thus showed divergent ecological responses along the abandonment gradient: bacteria exhibited stronger deterministic assembly associated with soil environmental gradients, whereas fungi retained greater stochasticity and depth dependence. These findings clarify the belowground ecological consequences of management cessation in moso bamboo forests of the central Hunan hilly region and highlight the need to consider both bacterial and fungal communities when assessing the ecological effects of bamboo forest abandonment.