Stara obora near Hluboka nad Vltavou (360-450 m a.s.l.) is a hunting game reserve with history that dates back to the 15th century. It contains fragments of pasture forests with veteran trees, and is an important refugium for saproxylic organisms. It is regarded as a high quality habitat, as it hosts many rare and endangered saproxylic beetles, not found elsewhere in the region, such as e.g. Rhysodes sulcatus, Ampedus quadrisignatus or Lacon lepidopterus. While its abiotic conditions are unexceptional, the locality is rich in dead wood of various sizes and quality owing to sporadic and almost nonexistent forestry practices, as dead and sick trees are left there to decompose naturally. It is currently protected as Site of Community Importance. Broadleaved species constitute approximately 50% of the trees, with the most abundant species being sessile oak (Quercus petraea), beech (Fagus sylvatica) and Norway spruce (Picea abies).
At this locality, we recently conducted a field work part of the study of Rhysodes sulcatus habitat preferences. 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 closeness, 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 only 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 leave large fallen logs inside the forest in order to support beetle populations.
This locality also served as one of our study site where we investigated the effect of deadwood microhabitats and sunlight on saproxylic communities. To cover a diverse spectrum of saproxylic beetles as well as some other taxa, we installed 24 window traps (16 beeches, 8 oaks) in Velký Kameník Nature reserve in 2018. A year later, we continued with the sampling and installed 12 more traps in the vicinity of Zlatěšovický rybník. During both years, we also collected some beetles that were used for isotopic analyses in order to find out the details about the trophic habits of saproxylic beetles. Among others, we found some interesting and rare species, e.g. Rhysodes sulcatus, Aesalus scarabaeoides or Sinodendron cylindricum.
Size matters! Habitat preferences of the wrinkled bark beetle, Rhysodes sulcatus, the relict of European primeval forests.Kostanjsek et al. 2018, Insect Conservation and Diversity
Biology Centre CAS Institute of Entomology Branišovská 31 370 05 České Budějovice Czech Republic