Functional traits drive ground beetle community structures in Central European forests: Implications for conservation

Community metrics describing the structuring of ecological communities, such as nestedness and the potential linkages between functional traits and the occurrence of species, might hold important information for biodiversity conservation. The order in which species are ranked in nested communities, as well as species traits determining community composition, can help pinpoint species vulnerable to extinction. However, these patterns remain understudied for many taxa of conservation concern and across larger spatial scales. We used a large dataset of ground beetle communities in Central European forests to test for nestedness, variation in species composition, and whether species traits can explain species composition patterns. We found only weak evidence of nestedness of ground beetle communities. However, community compositions across regions were remarkably similar. Species traits explained over half the variance in the overall occurrence ranks of ground beetle species. Wing dimorphism, breeding in both spring and autumn, and hibernation as both larval instars and as imago coincided with increasing occurrence probability, probably due to the greater flexibility of such species to adapt to fluctuating environmental conditions. In contrast, predominantly granivorous species or those with smaller geographical ranges had small occurrence ranks. These results emphasise the importance of investigating the relationships between species traits and occurrence ranks to better understand the mechanisms which shape community composition, and these relationships should be taken into consideration in conservation contexts. Our results provide a basis for the development of more effective conservation strategies in Central European forests to protect threatened ground beetle species.