Relationships Between Saproxylic Beetle Microhabitat Occurrences and Forest State Indicators

The use of proxies in habitat assessments has become widespread in recent decades. We used forest state descriptive data from a large-scale project (SCP) as proxies to investigate the occurrence of habitats suitable for some protected saproxylic beetles. We searched for pre-defined tree-related microhabitats (TreMs) suitable for saproxylic beetles in 1 ha quadrats in the Börzsöny Mts., Hungary. We compared the frequency of each microhabitat type with the aggregated values of the forest state proxies. Our results suggest that the average number of snags with DBH = 21–50 cm and the frequency of lying deadwood with Ø > 35 cm can adequately represent the occurrence of all beetle microhabitats studied. In most cases, the frequency of plots with species richness of live canopy trees with DBH > 35 cm and the amount of lying dead wood were also good indicators. The TreM indicators of the SCP alone can detect the presence of specialist beetles requiring cavities. The stands with a better forest state had more protected saproxylic beetles. The practical implementation of our work is based on the optimization of the resources required for monitoring. In surveys prepared to cover large areas, it is easier to monitor the habitat of saproxylic beetles with the help of individual proxies.