Spatial distribution of insect indicator taxa as a basis for peat bog conservation planning

Abstract

Peat bogs are highly endangered ecosystems worldwide. In the Western Balkans, they represent fragmented habitat patches, where insect diversity and implications for the habitat loss are poorly known. Carabid beetles and ants, widely used environmental indicators, were sampled by pitfall trapping in the largest and oldest Croatian peat bog and at its edges. We found that tyrphobiontic—bog specialist—species were absent in both taxonomic groups, which is likely due to biogeographical limitation for dispersal of these species into this region. With this study, tyrphophilous—typical of bogs—species have been recognised as environmental indicators in the Western Balkans peat bogs. Assemblages of both taxa were strongly affected by specific conditions in the peat bog – high soil moisture and Sphagnum moss dominance, showing that edges are more favourable habitats for both taxa. Overall, carabid beetle activity density was significantly higher at the edge than at the peat bog, while species richness increased for both taxa at the edge, but not significantly. Spatial distribution of tyrphophilous species differed between studied taxa, with ants being more abundant in the peat bog, and carabid beetles at the edge. Additionally, some stenotopic and globally endangered species preferred edges. Occurrence of tyrphophilous and globally endangered species highlights the great conservation value of peat bog habitats in the Western Balkans. However, successional changes in vegetation are changing hydrological conditions of the peat bog. Here we suggest active conservation measures to preserve these unique soil invertebrate zoocoenoses.