Arachnologische Mitteilungen 56

Arachnids in old oaks 25 cavities and by flight interception traps installed near their openings.The material was collected within a study primarily focused on saproxylic beetles associated with tree hollows. Material and methods Study area The study was carried out in the Lower Dyje (Thaya) flood- plain (48°43’10”N, 16°54’27”E, 150 to 165 m a.s.l.) south to southeast of the Pohansko hunting chateau and archaeologi- cal site, which is located ca. 3 km south of the town of Břeclav (South Moravia, CZECH REPUBLIC). This area had been historically used as a wood pasture; during the last two hund- red years, the more open areas were partially changed to hay meadows and the rest mostly to high forest for timber production. There is a high number of old trees, particularly pedunculate oaks ( Quercus robur ), both in the meadows and within smaller woods and larger forest stands, that had grown for a long time in open or semi-open conditions (Fig. 1).The study area, sampling design and sampling methods are de- scribed in detail in Schlaghamerský (2011) and Miklín et al. (2017). Sampling design Sampling was conducted in 2010 and 2011 (leg. J. Budka, J. Schlaghamerský). In 2010, 22 old oaks ( Quercus robur ) with cavities were studied. Ten (five live and five dead) were soli- tary trees in meadows. Twelve trees (seven live and five dead) were in close-canopy forest stands. All of the dead trees were standing. In 2011, a selection of 11 of these trees was resamp- led (traps remained on the same positions); only two of them were solitary trees in meadows (one dead), the rest growing in close-canopy forest (six live, three dead). Two sampling me- thods were used (their primary purpose was the sampling of saproxylic beetles associated with tree hollows). On each tree a flight interception trap (FIT) and a pitfall trap (PT) were installed. FITs hung near the opening of a selected cavity on a tree trunk. Cavity openings had to be at a height between 1.5 and 7 m above ground (Fig. 2a). Cavities with contact to the ground or entirely hollow trees were excluded. The FIT position was thus determined by the position of the opening of the cavity (into which a pitfall trap was also installed) and its distance from the tree crown varied substantially – in some cases it hung within the lowest part of the crown, often sub- stantially below it (due to the primary objective of their ins- tallation). FITs were of the vane type, made of two crossing sheets (50 cm × 25 cm) of transparent plastic, with a roof above and a funnel (24 cm in diameter) connected to a coll- ecting bottle attached below. As killing and preserving agent, an aqueous 50% ethylene glycol solution with a drop of deter- gent was used. Inside each tree cavity a pitfall trap was buried into the wood mould with its opening (6 cm in diameter) level with the mould surface (Fig. 2b). FITs and pitfall traps were exposed simultaneously from the 21 th April 2010 to 4 th October 2010 and from the 5 May 2011 to 23 August 2011 with three week sampling intervals. Spiders were identified using the key of Nentwig et al. (2018). Pseudoscorpions were identified using the key by Christophoryová et al. (2011c). Nomenclature for all taxa follows the World Spider Cata- log (2018) and the catalogue Pseudoscorpions of the World (Harvey 2013). The material of spiders and pseudoscorpions is deposited in the collection of the Department of Botany and Zoology at the Masaryk University in Brno. Results Spiders (Araneae) A total of 322 specimens representing 47 taxa from 15 fami- lies were identified (Tab. 1). FITs yielded 165 specimens be- longing to 40 taxa and 14 families. None of the species captu- red by the FITs were particularly abundant, only some species were present in relatively high numbers: Parasteatoda lunata (Clerck, 1757) (9 specimens), Anyphaena accentuata (Walcke- naer, 1802) (8), Porrhomma oblitum (O. P.-Cambridge, 1871) (8), Leptorchestes berolinensis (C. L. Koch, 1846) (8) and Plat- nickina tincta (Walckenaer, 1802) (8) (Tab. 1). FITs exclusi- vely yielded 27 spider taxa. Most species captured by FITs were Linyphiidae with nine species and a group of species Fig. 1: Closed-canopy forest with interspersed old oaks at the Po- hansko study site (photo J. Schlag- hamerský)