Long-Term Assessment of Wound Healing in Damaged Residual Trees Under Continuous Cover Forestry in the Hyrcanian Broad-Leaved Forests

The growing implementation of close-to-nature forestry practices in the management of northern forests, characterized by dispersed harvesting operations, has heightened the importance of minimizing damage to residual stands as a key aspect of sustainable forest management. The objective of this study is to examine and compare the resistance of various tree species and diameter classes to wounds incurred during logging operations of differing sizes, intensities, and locations. In addition, the research aims to assess temporal changes in wound characteristics, including healing and closure processes, across species. This long-term, 18-year investigation was conducted in the Kheyrud Forest, located within the Hyrcanian broadleaf forest region of northern Iran, to evaluate the dynamics of wound healing in residual trees following ground-based skidding operations. Through a comprehensive assessment of 272 wounded trees across six species, we demonstrate that species significantly influences healing ratio (Kruskal–Wallis, p < 0.01), with Oriental beech ( Fagus orientalis Lipsky) (50.6%) showing superior recovery compared to the Chestnut-leaved oak ( Quercus castaneifolia ) (37.5%). Healing ratio decreased with larger diameter at breast height (DBH) (R 2 = 0.114, p < 0.01), while absolute healed area increased. Larger areas (>1000 cm 2 ) reduced healing by 42.3% versus small wounds (<500 cm 2 ) (R 2 = 0.417, p < 0.01). Severe wounds (deep gouges) showed 19% less healing than superficial injuries ( p = 0.003). Circular wounds healed significantly better than rectangular forms (χ 2 = 24.92, p < 0.001). Healing ratio accelerated after the first decade, reaching 69% by year 17 (R 2 = 0.469, p < 0.01). Wound height ( p = 0.117) and traffic intensity ( p = 0.65) showed no statistical impact. Contrary to expectations, stem position had no significant effect on wound recovery, whereas wound geometry proved to be a critical determinant. The findings highlight that appropriate species selection, minimizing wound size (to less than 500 cm 2 ), and adopting extended cutting cycles (exceeding 15 years) are essential for enhancing residual stand recovery in close-to-nature forestry systems.