Responses of carabids and dung beetles to the windstorm “Vaia”: susceptibility versus resilience to disturbance

Climate change leads to extreme events whose ecological impacts are yet to be understood. The storm “Vaia” was an extreme climatic event that – in just one day (29th of October 2018) – caused considerable large-scale damages to forests in Eastern Italian Alps. To study the short-term impact of Vaia, we focused on carabids and dung beetles of Visdende valley (the northernmost tip of the Veneto region). We placed pitfall traps in four habitats, namely a mixed forest of spruce and beech, a pasture, a spruce forest, and a former spruce forest whose crashed trees had been removed. A total 28 species of carabids and 17 species of dung beetles were collected. In both groups mean values of species-richness, abundance and Shannon diversity did not vary significantly across the four habitats. Structural and functional species composition, however, changed significantly in ground beetles. We found that assemblages of the windthrown habitat, that lost typical forest species, were intermediate between those of the pasture and the spruce forest. In contrast, species composition did not change significantly across habitats in dung beetles. These results demonstrate that carabids are excellent indicators of extreme environmental changes and that dung beetles, responding primarily to the presence of dung, are much less reliable. However, dung beetles’ resilience potentially guarantees soil fertility in all habitats. Provided the availability of dung, they may support both restoration and eventual land use change after the passage of these windstorms.