The First Stages of Xylobiont Entomofauna Succession on European Silver Fir Logging Residues in Relation to Utilisation Method and Microenvironmental Conditions

摘要

The effect of post-cleaning Silver fir logging residues treatment method on the occurrence of early arriving xylobiont insects was studied in 2013 in two stands of fresh upland broadleaved forest and fresh mountain broadleaved forest habitats. At each study site, branches and tree tops were arranged in four piles and scattered disorderly in two plots. It was demonstrated that fine woody debris of fir, regardless of the disposal variant and habitat conditions prevailing at the place of leaving the material, were the breeding and the feeding base for Pityophthorus pityographus (Ratzeburg, 1837), Pityokteines vorontzowi (Jakobson 1895), P. curvidens (Germar, 1824) and Cryphalus piceae (Ratzeburg, 1837) (Coleoptera: Scolytinae). It was noted that the attractiveness of fir branches and tree tops for phytophagous insects increased proportionally to the stage of decomposition of logging residues. The influence of forest habitat and the method of fir slash utilisation, as well as microenvironmental conditions, prevailing in the material surroundings, on the severity of branch and tree top infestation by insects was not confirmed. It was, however, proved that fine woody debris of fir was the place of the occurrence of saprophages and natural enemies of bark beetles, i.e. predators, parasites and parasitoids. The most abundant entomophagous insect species was Phloeopora corticalis (Gravenhorst, 1802) (Coleoptera: Staphylinidae), whereas saproxylobiont entomofauna was represented mostly by insects from the order Diptera and family Mycetophilidae.