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Saproxylic beetles in Europe: monitoring, biology and conservation, p. 23–32 GDK 145.76(497.4) Biodiversity of saproxylic beetles of pine forests in Slovenia with emphasis on Monochamus species Maja Jurc1, Srdjan Bojovic2, Roman Pavlin3, Gregor Meterc4, Andreja Repe5, Danijel Borkovič6, Dušan Jurc7 Abstract From 2007 to 2010, we assessed the presence of entomofauna in two ecological regions of Slovenia on three locations: on limestone parent rock in monocultures of Pinus nigra, on flysch in a stand of Pinus halepensis (both in the Sub-mediterranean ecological region) and in a stand of Pinus sylvestris on brown soil (Pre-alpine ecological region). The samples were collected in one-month intervals from May to November using four cross vane funnel traps per location with wet collecting cups and attractants (ethanol+α- pinene, Pheroprax® and Gallowit®). Collected insects from the order Coleoptera belonged to the families Curculionidae (and subfam. Scolytinae), Cerambycidae and Buprestidae. The most important saproxylic groups were Scolytinae as the primary saproxylic beetles at 90.7% (21,820 specimens), containing 21 taxa and 18 species; Cerambycidae at 6.4 % (1534 specimens), 24 taxa, 20 species; Curculionidae at 2.5% (613 specimens), eight species and Buprestidae at 0.4% (90 specimens) and one species. With respect to the number of species identified, the most numerous family was Cerambycidae; the dominant species was Spondylis buprestoides, followed by Rhagium inquisitor, Arhopalus rusticus, Acanthocinus aedilis, Neoclytus acuminatus, Monochamus galloprovincialis, Leiopus nebulosus, Arhopalus ferus, Sticoleptura rubra and Cerambyx scopoli. Collected species of long-horned beetles represent ca. 10% of all known species of Cerambycidae in Slovenia. With regard to our findings, we can conclude that Slovenian forestry legislation (Act of Forestry 1993 and Rules on the Protection of Forests 2009) regarding the protection of forest biodiversity is appropriate for the preservation of saproxylics. Key words: Pine forests, saproxylic beetles, Cerambycidae, ethanol+α-pinene, Pheroprax®, Gallowit® 1. Introduction class of over 50 cm dbh. The second most common species of pine in Slovenia is P. nigra; its proportion the wood stock of pine is 25.3% or 4,935,411 m³ and appears on 67,882 ha, According to the data of the Slovenian Forest Service, while the area of stands with more than 50% of P. nigra in 2010 forests occupied 1,185,169 ha, which represents trees in the growing stock is 23,516 ha. The largest number 58.8% of the total surface area of the country. The growing of P. nigra trees according to the dbh is in the thickness stock of Slovenian forests was 330,982,374 m³ or 279.72 class 30–50 cm and it comprises 49.4%; in the thickness m³/ha. Conifer trees’ growing stock is 46.43%, and class of 10–30 cm it is 43.4% and 7.2% of the trees in the deciduous trees’ stock is 53.57%. The yearly increment thickness class of over 50 cm dbh (ZGS 2008a). of trees in the forests is 8,117,325 m³ or 6.85 m³/ha (ZGS In Europe and also in Slovenia, anthropogenic 2010). impacts on natural forest vegetation have been very In 2008, the share of all species of pines in the growing substantial; the result of those effects was (among others) stock amounted to 19,527,961 m³, which represents 5.9% in the loss of habitats of saproxylic organisms. In prehistoric the total growing stock of forests. In Slovenia the following times, inappropriate treatment with forests on the territory species of pines are present: Pinus nigra, P. sylvestris, of Slovenia took place, stacks of charcoal and ashes in P. mugo, P.halepensis, P. pinea, P. strobus, P. cembra, karst caves have been detected (JURHAR et al. 1963). P. pinaster, but only four of them are native (P. nigra, P. After the 15th century, areas were deforested with slash sylvestris, P. mugo and P. cembra). P. sylvestris dominates and burning; this continued until the 19th and 20th centuries among all pines, its proportion in the pine growing stock (Enciklopedija Slovenije 1995). P. nigra is found in the is 72.8% or 14,216,874 m³ and it appears on 310,513 ha, Sub-mediterranean ecological region and was planted in while the area of stands with more than 50% of P. sylvestris the 19th and 20th centuries during the period of the Austro- in the growing stock amounts to 36,833 ha. Up to 51.4% Hungarian Empire; since then, it has been regenerating of P. sylvestris is (according to diameter of breast height on abandoned land. This afforestation has been large and (dbh)) classified in the thickness class of 30–50 cm, 37.3% successful. Until recently, it has encompassed more than in thickness class of 10–30 cm and 8.3% in the thickness 20,000 ha of plantations and areas with natural regeneration 1 prof. dr. M. J., Biotechnical Faculty, Dpt. of Forestry and Renewable Forest Resources, Večna pot 83, 1000 Ljubljana, Slovenia; [email protected] 2 dr. S. B., Institute for Biological Research S. Stankovic, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade; Serbia; [email protected] 3 R. P., Biotechnical Faculty, Dpt. of Forestry and Renewable Forest Resources, Večna pot 83, 1000 Ljubljana, Slovenia; [email protected] 4 G. M., Biotechnical Faculty, Dpt. of Forestry and Renewable Forest Resources, Večna pot 83, 1000 Ljubljana, Slovenia; [email protected] 5 A. R., Biotechnical Faculty, Dpt. of Forestry and Renewable Forest Resources, Večna pot 83, 1000 Ljubljana, Slovenia; [email protected] 6 D. B., Biotechnical Faculty, Dpt. of Forestry and Renewable Forest Resources, Večna pot 83, 1000 Ljubljana, Slovenia; [email protected] 7 prof. dr. D. J., Slovenian Forestry Institute, Večna pot 2, 1000 Ljubljana, Slovenia; [email protected] 24 Saproxylic beetles in Europe: monitoring, biology and conservation of P. nigra. In the study area, P. nigra is not native, and to other European countries; it could become one of the it has been weakened by exposure to biotic and abiotic most serious threats to pine forests worldwide in the 21st damage. century (ØKLAND et al. 2010, TOMICZEK / HOYER- TOMICZEK 2008), including in Slovenia (JURC et al. Elswere in Europe, there was also no proper method 2003). of managing forests, so primeval forests in Europe are very rare; their surfaces are small and fragmented, and therefore A variety of approaches have been investigated for the saproxylic biodiversity is also diminished. The group the management of wood-boring insect populations. These of saproxylic beetles in Europe is, because of the small insects are attracted to potential hosts by volatile compounds amounts of decomposing wood in forests, one of the most and possibly by visual cues. Few studies have examined endangered groups of beetles; many of them are on the red traps of different designs to determine the influence of list of endangered species and lists of Natura 2000. silhouette and shape on the capture of Monochamus species. Groot and Nott (2002) have recommended a pan trap with In recent times, the saproxylic species are endangered a black silhouette for general use in capturing wood- in most of its original territory because of intensive forest boring Cerambycidae. Other authors have recommended management and the loss of primeval forest conditions. the use of conventional multiple funnel traps with certain Under the influence of fire and others factors, specific modifications, such as multiple funnel traps with water- habitats, such as old and dead trees, have disappeared. filled collecting cups or large-bottom funnels and cross The surface area of mature forests has been reduced, and vane traps with a prominent silhouette (MOREWOOD et there have also been changes in the size of patches of old al. 2002). Some authors have recommended the suspension trees (KOUKI et al. 2001). Data from the World Resources of multiple funnel traps from ropes between trees with the Institute from Washington shows that around 40% of uppermost funnel at a height of 1.8 m above the ground forests in the world still have characteristics of mature (IBEAS et al. 2007). forests. In some European countries, the proportions of mature forest are lower; for example, in Sweden the In North America, several researchers have proportion of mature forest is only 3% (BRYANT et al. demonstrated a kairomonal response of Monochamus 1997). Saproxylic organisms contribute significantly to titillator to blends of bark beetle pheromones acting forest biodiversity, representing 20–25% of all species synergistically with a turpentine host (BILLINGS / living in forests (SIITONEN 2001). CAMERON 1984, BILLINGS 1985). Other investigations have shown that ipsenol and ipsdienol, aggregation Analysis of the conservation of the forests in pheromones of Ips DeGeer, 1775 species, are highly Slovenia, however, shows a relatively favourable situation, synergistic with α-pinene and ethanol in attracting contributing to conservation of the habitats of saproxylic Monochamus clamator and Monochamus scutellatus, beetles. Based on the data from permanent sample plots whereas pheromone compounds from Dendroctonus in forests (n = 94,660) of the Slovenian Forest Service Erichson, 1836 species are not (ALLISON et al. 2003). (2008b), the amount of dead wood in forests is 3.6% of the In Spain, Pajares et al. (2004) have studied the effects of growing stocks of forest stands, representing 10 m³/ha of bark beetle (Ips spp.) pheromone components, released dead wood mass or 26 dead trees with diameters of more individually (ipsenol) or in blends (ipsenol, ipsdienol, cis- than 10 cm per ha of area. The proportion of deciduous verbenol and methyl-butenol), together with host volatiles trees is 56%, while the proportion of conifers is 44% (turpentine or α-pinene and ethanol) on Monochamus (POLJANŠEK 2008).