Mechanical Damage to Mixed Hardwood Regeneration Across Trail Systems and Harvest Intensities: A Seedling and Sapling Assessment

Mechanized harvesting, while central to modern forest management, can adversely affect natural regeneration and remains an important concern for sustainable forest management. These damages vary with operational, silvicultural and human factors, potentially influencing stand recovery and long-term value. However, how these impacts differ across regeneration growth stages remains poorly understood. Improving this understanding can support the development of more sustainable harvesting operations. Therefore, this study aimed to evaluate the effects of harvest intensity and machine trail configuration on regeneration damage across seedling and sapling growth stages in mixed-wood stands.

Data were collected from six treatment combinations representing two harvest intensities (27% and 40%) and three trail systems: conventional trails (CT), diagonal entries (DE), and ghost trails (GT), with five transects established per treatment. Regeneration was classified into seedlings and saplings, and damage was recorded using a nine-class system.

Seedlings showed consistently low damage with no significant differences among treatments (Kruskal–Wallis, p = 0.825). In contrast, saplings showed significant treatment-level variation (p = 0.0069), with higher damage frequency in 27% GT, 27% DE, and 40% GT relative to 40% CT (Benjamini–Hochberg adjusted p = 0.040). Mean severity was highest under 27% DE (0.655) and lowest under 40% CT (0.227), which also retained the greatest proportion of undamaged saplings (87.4%). Damage-type distributions differed significantly among treatments and regeneration stages (χ² tests, p < 0.001).

These findings suggest that saplings are more sensitive to harvesting conditions than seedlings and that trail system design may be as influential as harvest intensity in shaping regeneration outcomes in managed mixed hardwood forests.