Responses of carabid beetles to urbanization in Transylvania (Romania): Fid-Bau Portal

Responses of carabid beetles to urbanization in Transylvania (Romania)

Tóthmérész, Béla / Máthé, István / Balázs, Enikő / Magura, Tibor

Highlights ► Species richness was not entirely suitable to indicate the impacts of urbanization. ► Species with different habitat affinities should be considered separately. ► Diversity of forest specialist species decreased by the increasing urbanization. ► Diversity of generalist carabids increased by the urbanization. ► Both the proportion and density of matrix species were the highest in the urban area.

Abstract To investigate the impact of urbanization on carabid beetles samples were taken over two years using pitfall traps along a rural–urban forest gradient representing increasing human disturbance in and nearby the city of Sfântu Gheorghe (Romania). We predicted that total number of species should decrease, whereas number of opportunistic and matrix species should increase towards the urban end of the gradient. Both the overall species richness and the number of individuals were significantly the highest in the suburban area followed by the rural area and the lowest in the urban area. These findings contradicted the increasing disturbance hypothesis; the number of species did not decrease by the increasing disturbance. The proportion of the forest specialist individuals and species significantly decreased from the rural towards the urban area, supporting the habitat specialist hypothesis. An opposite pattern was observed in species richness of the generalist carabids, supporting the opportunistic species hypothesis. Both the proportion of matrix species and their density were significantly higher in the urban area, supporting the matrix species hypothesis. Our findings also highlighted that overall diversity is not an appropriate indicator; species with different habitat affinities should be analysed separately to evaluate the real effect of urbanization.