Ecology and calculation of population density of the protected saproxylic beetle species Boros schneideri (Panzer, 1796) (Coleoptera, Boridae) in capercaillie lek areas

Boros schneideri is an endangered saproxylic beetle species in Europe, included in the list of species for which micro-reserves are established in Latvia. Micro-reserves for capercaillie lek areas are created in similar habitats in Latvia; therefore, these sites might be suitable for B. schneideri and play an important role in the protection of the species. This study aimed to identify ecological factors affecting the occurrence of B. schneideri and to estimate the species’ population density in Central Latvia. In total, six micro-reserves (primarily established to protect capercaillie lek areas) and six, randomly picked, control territories were examined, including 304 forest stands and 312 pine snags. In total, 109 B. schneideri specimens were found. The most important ecological factors for B. schneideri were the age of the forest stand, the presence of deadwood in different stages of decomposition, and the number of snags per forest stand. All mentioned factors are important structural elements of natural forests; hence, B. schneideri can be considered as an indicator species of natural forest habitats. The most important ecological factors for B. schneideri on a micro-habitat scale are the area and thickness of the remaining bark, presence of Ascomycota fungi mycelium on a trunk, and trunk’s circumference. We suggest that B. schneideri is a pioneer species since larger areas of bark, as well as Ascomycota fungi mycelium are more often found on recently dead trees.