Importance of stochastic assembly processes influencing beetle communities increases after logging

Abstract

Xerothermophilous beetles are one of the endangered ecological groups of animals, mainly because of the loss of suitable habitats for their development. Many species of these beetles are associated with specific light conditions. Those preferring higher insolation levels may find such conditions in coppices. Coppicing is a type of forest management with a long history, which allowed the survival of many species in the European landscape. After WWII coppicing management was widely abandoned and coppices were transformed into high forest, which caused a significant decline in forest biodiversity. In the Podyjí National Park at the border of Czechia and Austria, coppicing was re-established in two neglected coppices by cutting trees on areas of approximately one hectare in the winter of 2015/2016 to support heliophilous and endangered species of plants and animals. We carried out a study in these two areas by using flight interception traps during the year before the logging (2015), and two years after the logging (2016 and 2017). We analysed the effect of the logging and the following succession on beetle assemblages by comparing beetle taxocoenoses before and after logging. The creation of the clearings in closed-canopy forests had a positive effect on overall species richness and supported threatened species of beetles. We revealed that unlike α-diversity, which was highest during the first year after logging, spatial differentiation of the assemblage (β-diversity) was highest during the second year after logging. Co-occurrence analysis showed that beetle assemblages tended to co-occur more than expected by chance during all study years, indicating shared environmental preferences. On the other hand, after logging the species co-occurrence pattern was closer to random species distribution, showing that dispersal ability and random immigration also play important role in assembly processes.