Soil physical structure and aggregate stability dynamics during pit-mound microrelief development

Tree uprooting is a prevalent natural disturbance in primary forests, creating pit-mound microrelief that initiates a natural chronosequence of soil recovery. Using this chronosequence in a wind-disturbed Korean pine forest in Northeast China, we investigated the dynamic evolution of soil physical structure and aggregate stability across decay classes and soil depths. Through variance analysis, correlation analysis, and structural equation modeling, we elucidated how soil physical properties regulate aggregate stability. Our results show that pit-mound morphology evolves systematically with log decay, directly driving the reorganization of soil profiles. Morphological parameters are closely linked to soil organic matter, pore structure, and aggregate stability, confirming microtopography as an active driver of soil recovery. The influence of decaying logs on soil physical properties is strongly depth-dependent: the 0–30 cm layer functions as a biophysical coupling zone, while soil below 50 cm remains largely inert. Aggregate stability recovery peaks at decay class III and 30 cm depth, coinciding with optimal pore structure, moisture, and organic matter conditions. A unified recovery framework emerges, comprising morphological reorganization, physical restructuring, and aggregate stabilization, with depth-dependent decoupling of active surface recovery and physically protected deep-soil stabilization. These findings advance understanding of the disturbance-recovery-stability continuum in forest soil systems.