Acta Zoologica 46. (2000)
2000 / 1. szám - MAGURA TIBOR - TÓTHMÉRÉSZ BÉLA - MOLNÁR TIVADAR: Spatial distribution of carabids along grass-forest transects
Acta Zoologica Academiae Scientiarum Hungaricae 46(1), pp. 1-17, 2000 SPATIAL DISTRIBUTION OF CARABIDS ALONG GRASS-FOREST TRANSECTS Magúra, T.1, B. Tóthmérész2 and T. Molnár1 1Department of Zoology, Kossuth L. University POBox 3, H-4010 Debrecen, Hungary E-mail: magúra @ tigris, kite, hu 2Ecological Institute, Kossuth L. University POBox 71, H-4010 Debrecen, Hungary E-mail: tothmerb @ tigris, kite, hu Spatial distribution of ground-beetles and associations between carabids and environmental variables were studied in grass-forest transects in the Aggtelek National Park in Hungary. The carabid assemblages of the grass, the forest edge and the forest interior can be separated from each other by principal coordinates analysis, suggesting that all habitats have a characteristic and distinct species composition. The collected carabid species can be divided into five groups by indicator species analysis: (1) habitat generalists, (2) forest generalists, (3) species of the grass, (4) forest edge species, and (5) forest specialists. Distributions of the eighteen most frequent carabids were generally aggregated. There were significant correlations between the carabid abundance and the following abiotic factors: relative cover of the leaf litter, the herbs, the shrubs, and the canopy layer. Biotic factors, like the abundance of the carabids’ prey, and the occurrence of other carabids were also correlated significantly with the distribution of particular species at the studied spatial scale. For the eighteen most frequent species we found 7 significant positive and 4 significant negative correlations of the abundance patterns. For two species (Molops piceus (Panzer, 1793) and Pterostichus burmeisteri Heer, 1841), which are of similar size, spatial pattern and seasonal activity, we found significant negative interaction suggesting interspecific competition between them. The results stress the importance of an integration of biotic and abiotic factors in carabid ecology, and also provide an empirical approach for understanding spatial distribution of carabids. Key words: forest edge, aggregation indices, indicator species, community organisation INTRODUCTION There is a current debate whether the spatial distribution of a species in a community is determined by their autecological characteristics or by community organisation (NiEMELÄ & SPENCE 1994, LÖVEI & SUNDERLAND 1996). Quantitative knowledge about habitat associations and spatial pattern of carabids in Hungary is relatively poor. Further studies, based on comparisons among habitat types are necessary to demonstrate more precisely the habitat requirements of carabid species. This knowledge is essential to assess the relative importance of environmental factors and species interactions in structuring communities in different habitats. Knowledge of exact habitat requirements is also Actazool. hung. 46, 2000 Hungarian Natural History Museum, Budapest