Effect of thinning and ground-based skidding on soil mite diversity in temperate beech forests

Forest operations, particularly ground-based skidding, are known to cause soil disturbances, yet their long-term impact on soil biological communities remains understudied. The goal of this study was to assess the effects of thinning and skidding on Mesostigmata mite communities in Polish beech forests, analyzing soil disturbance in skid trails, undisturbed harvested areas, and unharvested control sites. This study is especially needed in Polish beech forests, considering that recently both the shift towards continuous cover forestry and the increasing demand for beech timber have fostered the shortening of the re-entry intervals between two consecutive logging operations in the same forest management unit. Further to the above, the aim of this study was to leverage a well-recognized indicator of soil health, i.e. mite biodiversity, to check both the short-term consequences of ground-based forest operations and the related recovery times after harvesting. A total of 670 individual mites from 49 taxa were identified, with significant reductions in abundance and diversity in the disturbed soil. Mite abundance in recently established skid trails was approximately 80% lower than in unharvested control sites, while species richness and diversity were reduced fivefold. Even five years after logging, mite abundance and diversity remained three times lower than in unharvested stands, indicating prolonged recovery. Unexpectedly, uncompacted soil within harvested blocks also showed a 50–75% decrease in mite diversity, suggesting that thinning alone can significantly affect soil mites. Statistical analyses revealed strong correlations between mite abundance and soil penetration resistance and organic matter content, emphasizing the role of both compaction and organic matter depletion in shaping soil biodiversity. Given that the current re-entry interval is insufficient for biological recovery, forest management should consider increasing the re-entry interval, implementing further soil protection measures to skid trails, and assessing alternative extraction methods, e.g. forwarding. These findings highlight how integrating soil biological indicators into forestry operations planning can lead to lowered impacts on soil and soil biota.