Speaker
Description
There is growing evidence of a worldwide insect decline, caused by various pressures such as natural habitat loss, chemicals, or warming temperatures. However, not all insects are impacted in the same way, and long-term monitoring coupled with a trait approach can be a powerful tool for understanding the drivers and consequences of these environmental changes. Here, we use data from two semi-natural areas in Drenthe, the Netherlands, where ground beetles (Coleoptera: Carabidae) have been sampled using pitfall traps since 1959. These areas consist mainly of heathland and are isolated in a highly intensive agricultural landscape. Over the years, numerous restoration events have taken place in the form of vegetation burning and topsoil removal. This dataset has already been partially analysed, showing a decline in abundance and biomass, but it is not known which species are the most affected, and what environmental factors might be driving these trends. Thus, using GLMMs, we computed and compared the trends of different beetle groups, based on their habitat preferences, breeding season, and dispersal. We hypothesised that the trends of the first two groups are mainly related to climatic factors, while the trends of the third group might be related to habitat fragmentation. Over the whole period, all the beetle groups were found to decline, with the exception of the forest species and the fall breeders. The fastest declining beetles were the wetland and heathland species, as well as those with lower dispersal ability. Most of these trends were similar with and without restoration, but, overall, we found a significantly steeper declining trend in the sites present in the restored areas. These results suggest that the restoration measures are not sufficient to address the decline of insects. Also, for the low dispersal species more efforts are needed to increase the connectivity to other natural areas.
| Status Group | Master Student |
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