The effect of grazing on the spider assemblages at the Hortobágy National Park in Hungary
Abstract
The effect of grazing on the assemblages of ground-dwelling spiders were studied by pitfall traps at the Hortobágy National Park. There were two research sites, characterized by different grazing regimes: (1) Angyalháza was intensively grazed by sheep, while (2) Pentezug was grazed by horses and native cattles. There were four vegetation types in both areas (salt meadow, salt steppe, salt steppe with open soil surface, and degraded salt steppe). Traps were emptied from April until October during 2004 every three weeks. There were eight traps in each vegetation type. During the study we trapped 82 spider species and 4363 individuals. The following rare species were identified (Gnaphosa rufula, Micaria rossica, Titanoeca vetercmica). The ordination of the spider assemblages revealed that the spider assemblage was different at the intensively grazed site. The indicator species analysis (IndVal) revealed that there are significant character species for both sites although most of the species are not sensitive to disturbance because they occurred in large number at both sites. Our results show that the ground-dwelling spider assemblages of similar habitat types can very as a result of different levels of grazing intensity. The results also suggest that grazing does not substantially harm ground-dwelling spider assemblages.
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