Arachnologische Mitteilungen 58

26 L. Bali, D. Andrési, K. Tuba & C. Szinetár tionally, the D-Vac data shows that the highest [mm] values are in the stands, while the lowest are in the gaps (Tab. 1.). Examining the family-structures of the samples conside- ring the two sampling method, it can be stated that the share of the family Linyphiidae regarding both the total species and specimen numbers were higher in the D-Vac samples. We got the same results for the family Gnaphosidae in the pitfall samples. Furthermore, the share of the family Lycosi- dae in the total specimen numbers was higher in the pitfall samples (Tab. 2.). Additionally, the guild analysis showed that the majority of the spiders (considering both S and n) were hunters in the pitfall traps, and web builders in the D-Vac samples (Fig. 3.). The Renkonen similarity values showed that four of the D-Vac samples show the highest similarities to those pitfall samples which are located in the gaps (Tab. 3.). In the ordination analysis, the samples of the two methods are organised into two distinct groups. Both the largest simi- larities and largest dissimilarities can be seen in case of the pitfall traps.The superimposed minimum spanning tree indi- cate fairly good 2D solutions (Fig. 4.). According to the regression analysis, the distance of the sampling sites shows significant relationships with specimen number, species number and diversity in case of the pitfall traps; and only with specimen number in case of suction sam- plings. All these values show negative connection.The R 2 va- lues are generally low, the highest being 0.38 (Tab. 4.). Discussion The total sample size of the pitfall traps may be considered lower than expected.The specific reason for this is unknown, but some factors may be partially responsible: the dry micro- climate of the investigated forest, the big game activity in the area and the carabid attractive properties of the acetic acid. Both the total and the relative catching numbers were higher using the suction sampling method. The formation of two distinct groups can be interpreted in the ordination analysis as the two methods accessed somewhat different communities, which is in line with the findings of Samu & Sárospataki (1995), Green (1999) and Cardoso et al. (2008). The reason the D-Vac samples were mostly similar to the gap located pitfall samples (according to the Renkonen indices), might be that the gap located pitfall traps caught more small Tab. 3: Renkonen similarity index values between the samples of the two methods. Samples located at the same relative positions in the transects are summarized (PT – pitfall trapping; DV – suction samplings; numbers in brackets represent the distance [m] of the sample site from the centre of the gaps; highest values in bold ) DV.1(0) DV.2(7.5) DV.3(15) DV.4(30) DV.5(45) PT.1(35) 0.21 0.26 0.32 0.15 0.09 PT.2(30) 0.21 0.29 0.29 0.23 0.17 PT.3(25) 0.18 0.26 0.29 0.12 0.09 PT.4(20) 0.39 0.46 0.48 0.24 0.25 PT.5(15) 0.25 0.26 0.40 0.20 0.13 PT.6(10) 0.32 0.43 0.58 0.33 0.23 PT.7(5) 0.33 0.50 0.49 0.35 0.29 PT.8(0) 0.37 0.53 0.46 0.34 0.28 PT.9(5) 0.34 0.45 0.54 0.37 0.34 PT.10(10) 0.29 0.42 0.41 0.25 0.25 PT.11(15) 0.30 0.37 0.40 0.28 0.17 PT.12(20) 0.21 0.26 0.40 0.20 0.09 PT.13(25) 0.25 0.32 0.45 0.20 0.18 PT.14(30) 0.25 0.26 0.32 0.15 0.09 PT.15(35) 0.25 0.29 0.29 0.24 0.16 Tab. 2: Family compositions. Values represented as percentages of the total catch results (PT – pitfall trapping; DV – suction sampling; highest differences in bold ). Taxa Specimen number Species number PT DV PT DV Agelenidae 0.97 0.19 2.94 2.13 Atypidae 2.70 0.19 2.94 2.13 Clubionidae 0.11 0.10 2.94 2.13 Dictynidae 0.11 0.00 2.94 0.00 Dysderidae 0.22 0.10 2.94 2.13 Gnaphosidae 9.06 1.46 11.76 2.13 Hahniidae 0.00 0.19 0.00 2.13 Linyphiidae 4.31 50.58 0 20.59 40.43 Lycosidae 74.43 37.04 8.82 6.38 Mimetidae 0.00 0.19 0.00 2.13 Miturgidae 2.70 1.95 5.88 4.26 Mysmenidae 0.00 0.78 0.00 2.13 Philodromidae 0.54 0.39 2.94 2.13 Phrurolithidae 0.32 0.19 2.94 2.13 Pisauridae 0.11 0.00 2.94 0.00 Salticidae 0.97 2.14 8.82 6.38 Tetragnathidae 0.00 0.19 0.00 4.26 Theridiidae 0.86 1.66 11.76 10.64 Thomisidae 0.76 2.63 5.88 6.38 Zodariidae 1.83 0.00 2.94 0.00 Fig. 3: Guild structure of the communities accessed by the two sampling methods (PT – pitfall trapping; DV – suction sampling; S – species number; n – specimen number)