Dead wood complexity shapes the pattern of the occurrence of threatened saproxylic beetle Cucujus cinnaberinus

Saproxylic beetles are essential for the proper functioning of forest ecosystems. However, intensive forest management has led to the disappearance of suitable microhabitats of many species associated with dead wood. Cucujus cinnaberinus is an endangered saproxylic beetle which develops under the bark of dead wood. The species usually occurs in protected areas, however, some populations inhabit long-term managed forests in Central Europe. In this study, we analyzed the effect of nine silviculture-related and decay-related factors on the C. cinnaberinus microhabitat selection in managed forests. We found that potential sun exposure, bark thickness, dead wood moisture and the hardness of dead wood have a significant effect on the C. cinnaberinus microhabitat selection. The species prefers sun-exposed dead wood with thicker bark at an intermediate stage of decay with undecomposed xylem, but avoids completely dry pieces. Furthermore, we found no confirmation of a direct connection between dead wood diameter and the occurrence of C. cinnaberinus. We stressed that logging residues or stumps are mostly unsuitable for C. cinnaberinus development.