S. Mahunka szerk.: Folia Entomologica Hungarica 54. (Budapest, 1993)

series of traps functioned only through a year. The traps were plastic cups with a diameter of 7 cm and a deepth of 13 cm, they contained ethylene-glycol. The material collected by pitfall traps was statistically examined by using ordination and classification techniques and by calculating habitat fidelity and habitat selection index. We have analysed data by clustering procedure to make classification on the basis of the methods described by Ludwig and Reynolds (1988). The elements of distance matrix were 1-Re values of data, where „Re" was the Renkonen-number (Renkonen 1938). We have used SYN-TAX III program package (Podani 1988) to perform Correspondence Analysis to make ordination. We have calculated the habitat fidelity (HF) values and the habitat selection indexes (HSI) by the formula of Buse (1988). For the theoretical background of our calculations see Digby and Kempton (1987), Buse (1988), Ludwig and Reynolds (1988), etc. Result and discussion The total number of adults caught by pitfall traps was 3058, belonging to 23 species. The list of the species and the numbers of specimens are given in Table 1. The most abundant species was Aptinus bombarda. Its distribution is well known (Casale and Vigna Taglianti 1983). It was found in many habitats (Brandmayr 1974, Tóth 1980, Pravisani andTorossi 1987 and Fazekas et al. 1992) but with an extremely high dominance value, it occurred only in the sampling site (Seslerio-Quercetum) of Brandmayr et al. (1980). The „FO" habitat seems to be favourable for A. bombarda. However, high catches of this species in the traps could have resulted from an aggregative response which response has already been shown with other carabids (Luff 1986). The other two most abundant species were Abax parallelepipedus and Pterostichus oblongopunctatus, which were demonstrated to be abundant in different types of associations as well (e.g. Paarmann 1966, Brunsting 1981, Janssen 1982, Baguette 1987, Desender et al. 1987, Niemelä et al. 1988 and Andersen et al. 1990). A. parallelepipedus is brachypterous, while P. oblongopunctatus is macropterous (den Boer 1977, Desender 1986) and both have a low power of dispersal (den Boer 1977). Eleven species of the sixteen in Table 1 are brachypterous and the majority of those has a low dispersal power, too. This is important, because the brachypterous species are positively related to the stability of an ecosystem (Brandmayr et al. 1983), thus in case of rapid changes of certain sites, species with low dispersal power are possibly endangered (Turin and den Boer 1988). Table 1. Species and number of ground beetles collected by pitfall traps from six habitats of Nagy-szénás, Hungary, 1983-85. (For the abbreviations, see chapter of Material and Methods) Species Number of Individuals BR 1. Carabus convenus Fabricius, 1775 2. Carabus coriaceus Linnaeus, 1758 3. Carabus hortensis Linnaeus, 1758 4. Carabus nemoralis Müller, 1764 5. Carabus scheidleri Panzer, 1799 6. Leistus rufomarginatus (Duftschmid, 1812) 7. Plerostichus melas (Crcutzcr, 1799) 8. Plerostichus oblongopunctatus (Fabricius, 1787) 9. Abax ovalis (Duftschmid, 1812) 10. Abax parallelepipedus (Piller ctMittcrpachcr, 1783) 11. Pristonychus terricola (Herbst, 1783) 12. Molops piceus (Panzer, 1793) 14 10 1 29 2 9 6 2 FO 1 1 2 3 35 5 70 64 12 26 QC 9 5 6 5 2 19 37 118 2 133 15 20 MF 13 6 6 10 42 44 106 255 13 56 PN 2 2 10 4 33 3 7 3 48 7 I FA 27 106 17 49 5 15