Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 83. (Budapest 1991)

Báldi, A. ; Ádám, L.: Habitat selection of ground-dwelling beetles during dolomitic succession

246 A. Báldi & L. Ádám We put 108 pitfall traps in each of the habitats, altogether we had 432 traps. The mouth diameter of the jars was 9 cm. The investigation went on from April to October in 1988. Traps were sampled in every two weeks. We used for each species an independent and comparable habitat fidelity index for each habitat, developed by BUSE (1988). The formula was: habitat fidelity = (pHi - pHj')/(pHi + pHQ where pHi = ni/n and pHi' = (n-ni)/((N-l)*n), ni: number of individuals in habitat i, n: number of individuals in all habitats, N: number of habitats, Hi: habitat i, Hi': all habitats except i. The values of this index ranged from -1 to +1. The maximum value, +1 showed that all individuals of the given species were in the given habitat, whereas -1 indicated that no individuals of the species were recorded in the habitat, and 0 indicated that there was an average number of individuals in the habitat (BUSE 1988). The sum of absolute values of the four indices for a species gives the habitat selection index of the species (BUSE 1988). To avoid increasing noise in abundance of less dominant species, the 22 most abundant species out of the total 349 were selected for the analyses of habitat selection and habitat fidelity. In this data set more than 100 individuals were presented for all of the habitats. The records of the fourteen trap controls were pooled. The beetle species were clustered into five groups based on their feeding types. These five groups were the following: herbivores, predators, scavengers, dung feeders and detritus feeders. For agglomerative cluster analysis the statistical program package of SPSS\PC+ (NORUSIS 1986) was applied, choosing the squared Euclidean distance measure. The same program package was applied for correlation analysis. For the analysis of temporal changes of habitat fidelity and habitat selection the six most abundant beetle species were selected. Traps which collected less than ten individuals of a species during the two week period were omitted from the analysis of temporal changes. Table 1. Values of habitat fidelity and habitat selection indices for beetle species of different stages of dolomitic succession. The species were grouped into five groups according to their feeding types (A - predators, B dung feeders, C - scavengers, D - detritus feeders, E - herbivors) Habitat fidelity index Habitat Selection Index HSI Mean HSI Oak forest Dolomitic steppe meadow Dolomitic Open grassland Close Habitat Selection Index HSI Mean HSI A. Pseudocypuspicipennis -0.60 0.29 -0.83 0.52 2.25 Carabus convexus 0.97 -0.98 -0.95 -0.95 3.85 Calathus fuscipes -0.48 0.84 -1.00 -1.00 3.31 Pterostichus melas 0.99 -0.97 -0.99 -1.00 3.% 3.21 Abax ater 1.00 -1.00 -1.00 -1.00 4.00 Ocypus olens 0.40 -0.49 -0.86 -0.12 1.87 B. Onthophagus fracticomis -0.58 0.87 -0.98 -1.00 3.43 Geotrupes vernalis 0.77 -0.39 -0.89 -0.99 3.04 Sisyphus schaefferi -0.50 0.71 -0.59 -1.00 2.81 3.07 Onthoph. grossepunctatus -0.35 0.67 -0.69 -1.00 2.71 Onthophagus nutans 0.84 -0.50 -1.00 -1.00 3.34 C. Thanatophilus rugosus 0.00 0.56 -0.91 -0.98 2.46 Nicrophorus humator 0.62 -0.51 -0.42 -0.97 2.53 2.40 Nicrophorus vespillo 0.68 -0.43 -0.60 -1.00 2.71 Nicrophorus vespilloides 0.38 -0.05 -0.45 -1.00 1.88 D. Pedinus femoralis -1.00 -0.02 0.61 -0.99 2.63 Gnaptor spinimanus -0.98 0.00 -1.00 0.59 2.58 3.14 Crypticus quisquilius -1.00 0.85 -0.84 -0.65 3.35 Amphotis marginata -1.00 -0.98 -1.00 1.00 3.98 E. Zabrus spinipes -1.00 -0.29 -1.00 0.76 3.04 Cetonia aurata -0.92 -0.78 -0.85 0.87 3.42 3.44 Potosia cuprea obscura -1.00 -0.89 -0.98 0.97 3.84