Size matters! Habitat preferences of the wrinkled bark beetle, Rhysodes sulcatus, the relict species of European primeval forests

Abstract

Abstract The wrinkled bark beetle Rhysodes sulcatus is an endangered saproxylic beetle listed in the European Habitats Directive and in the Bern Convention (Annex II). It is considered a relict of primeval forests and belongs among the most threatened saproxylic beetles in Europe. The purpose of this study was to identify the key habitat requirements of the species. The study was carried out at several locations within different forest types in mid elevation forests dominated by oak, beech and spruce and montane beech‐fir forests in the Czech Republic, Slovakia and Croatia. Coarse woody debris was checked for the presence of the beetle, and parameters of each inspected dead wood unit and its surroundings were recorded, including diameter, length, humidity, insolation, decomposition level and rot type. Surrounding forest characteristics, such as canopy density, main tree species, undergrowth, the amount and quality of the dead wood were also recorded. The analysis shows that the presence of the beetle is affected mainly by the diameter of dead wood as well as its humidity, as R. sulcatus was almost exclusively found in large, moist and well rotten fallen logs with a diameter greater than 60 cm. These findings may provide useful guidelines for sustainable forest management, specifically emphasising the need to retain large fallen logs at sites inhabited by R. sulcatus populations.