Ground beetles were studied among grassland — forest edge — beech forest habitats in Hungary, using pitfall traps. We hypothesised that the activity density and species richness of carabids were the highest in the forest edge, the activity density and the number of forest species were decreasing, while the activity density and the number of generalist species increasing from the forest towards the grassland. Carabid assemblage of the grassland was the most diverse and the forest was the least diverse if measured by Rényi diversity. The average species richness per trap was significantly higher in the grassland and in the edge than in the forest. The number of forest species was significantly higher in the edge than elsewhere. The number of generalist species was highest in the grassland and decreased towards the forest. The activity density of carabids was significantly higher in the forest and in the forest edge than in the grassland. The activity density of forest species was higher in the forest and in the edge than in the grassland. The activity density of the generalist species was higher in the grassland than in the forest edge and in the forest. There were seven species characteristic to the grassland as identified by IndVal; two species were characteristic to the edge, and two species were characteristic both to the forest and the edge. We found that humidity was the highest in the forest; Pterostichus oblongopunctatus and Molops piceus were associated with the forest habitat, while Abax ater and Pterostichus melanarius were associated with the forest edge according to the RDA. The the shrub cover was the most relevant factor in the edge; Abax ater and Pterostichus melanarius were associated with this habitat.
Diversity relationships of carabids in forest edges and the neighbouring forest interior and the surrounding grassland were studied. Samples were taken along three replicated forest-grassland transects using pitfall traps in the Várghis-valley (Harghita County, Romania). The study revealed significant edge effect on the carabids. Both the number of species and the Shannon diversity of carabids were significantly higher in the forest edge than in the grassland and in the forest interior. The forest was also significantly more species rich and more diverse by Shannon diversity than the grassland. Carabids of the forest interior, forest edge and grassland can be separated from each other by ordination based on abundances, suggesting that all three habitats have a distinct species assemblage. Indicator species analysis detected significant edge associated species. Our results show that the high diversity of carabids in forest edges is due both to the edge-associated species and the presence of species characteristic of the adjacent habitats.
Natural habitat edges are known to influence the vegetation structure, the microclimate and thereby the invertebrate assemblages. We studied the spiders of two forest edges in the forest-steppe zone of the Great Hungarian Plain (Site 1: a dense juniper shrub — open grassland and Site 2: a juniper and poplar forest — open grassland edge, respectively). The spider assemblages were sampled with pitfall traps arranged in 5 × 20 grid at the habitat edges. Observed and estimated species richness was higher for the grasslands than for the forests. Renyi’s diversity ordering was applied to compare species diversity. The results showed that the grasslands were more diverse in terms of spider species than the forests. The composition of spider assemblages was significantly different between the two habitat types. At Site 2, a higher number forest specialists penetrated into the grassland. Presumably this was due to the shading effect of the nearby poplar trees. Constrained ordinations also revealed a strong influence of the neighbouring poplar trees and vegetation structure on the spider assemblages. No exclusively edge associated species were found on either of the two sharp forest edges.
Authors:D. Andrési, L. Bali, K. Tuba, and Cs. Szinetár
Artificial gap openings cause significant changes in vegetation structure (in every forest level), thereby greatly influencing arthropod communities. Our study compared the data of two common forest floor arthropod groups, ground beetles (Coleoptera: Carabidae) and ground-dwelling spiders (Araneae) from two artificial gaps situated in a turkey oak forest. Our surveys were carried out in the Gyöngyös-plain, in Hungary. Sampling of the arthropod communities was done with pitfall traps arranged in two 70 m long transects, along the longitudinal axis of the gaps, with 15 traps in each transect, 5 m from each other. We measured the quantity and quality of the deadwood lying around within a radius of 2.5 m of each trap. We observed that the species and numbers of spider specimens were higher in the inner parts of the transects (in the gaps), while the numbers of ground beetle specimens declined in the same traps. Furthermore, the Shannon and Simpson diversity values of the ground beetles were generally lower than those of the spiders. The ordinations showed a distinct influence of the gaps on the communities. The numbers of specimens of exclusively edge-associated species were also higher in the gaps. The correlation analysis indicated significant positive correlations between the number of ground beetles and spiders and the quantity of deadwood. In addition, there were significant negative correlations between the numbers of species of both groups and the rate of decay of deadwood.