Functioning of Ecotones — Spiders and Ants of Edges Between Native and Non-Native Forest Plantations

Abstract

Habitat edges are regarded as important components of heterogeneous landscapes. Diverse theories exist about the diversity and functional role of edges, and no generalisation have been possible so far, thus case studies are important for better understanding the landscape scale processes. Forest management highly modified the structure and tree species composition of the European forests. The sylvicultural intensification resulted in the rise of the proportion of non-native, intensively managed forest stands. In the present study we explore the response of spider and ant assemblages to forest stand type and the edge effect between native poplar and nonnative conifer plantations in Hungary. We applied pitfall traps to sample the ground-dwelling spiders and ants. Four plots consisting of the two forest types and the transition zones between them were selected. Five transects for each replicated plot were sampled. We identified the significant indicator species of the different habitat types. We found significant differences in the species richness (i.e. number of species) of ants and spiders of the different habitat types. We detected intermediate spider species richness at the edge indicating that edges separate a higher quality habitat from one that has lower resource quality; however, the species richness of ants was the highest at the edge and did not differ between the two forest types. The positive impacts of edge was found due to presence of generalist and grassland species at the edge and presumably edges separate patches that provide complementary resources also increasing the number of ant species.Our results indicate that forest type affects the species compositions of ground-dwelling spiders and ants. Our study also shows that habitat type had a major effect on the species richness and composition of spider and ant assemblages, suggesting that local forestry management plays a crucial role in preserving the native invertebrate fauna of forests.