Branch piles as microhabitats for soil mesofauna: Responses to management-created deadwood structures

Integrating structural elements such as deadwood into managed forests is increasingly recognised as an important strategy for biodiversity conservation, including soil-dwelling communities. However, the effects of management-created woody structures on non-saproxylic soil fauna, and their dependence on forest management and season, remain insufficiently understood. We investigated how branch-pile microhabitats affect soil mesofaunal density and community composition, whether these effects depend on forest-management treatment, and how they vary seasonally in an 80-year-old oak-hornbeam temperate forest. Eight years after branch-pile establishment, we compared three microhabitats: beneath branch piles, immediately adjacent to them, and open litter-covered soil, across five forest-management treatments and three seasons. We assessed mesofaunal density and community composition, with Collembola examined at finer taxonomic resolution. Branch-pile microhabitats were associated with higher densities of most mesofaunal taxa across forest-management treatments, indicating consistent effects across management contexts. Rather than strongly altering overall community composition, branch piles primarily functioned as local hotspots of mesofaunal density. The observed patterns were more consistent with increased resource availability and structural complexity than with microclimatic buffering. Microhabitat effects were weak in spring but stronger in autumn, when branch-pile-associated soils showed greater accumulation of organic matter, nutrients and higher densities of several taxa, despite lower soil moisture beneath the piles. Collembola showed higher species richness and distinct assemblages associated with branch piles, particularly among epigeic and hemiedaphic taxa. Retaining management-created branch piles may therefore provide a practical means of increasing structural heterogeneity and supporting soil biodiversity in managed forests.