Varied forests with a large amount of deadwood are essential for preserving the different beetle species that depend on decaying wood. This is shown by a study from the Swedish University of Agricultural Sciences (SLU), where researchers examined beetles’ ecological traits and environmental factors in areas with different types of forests.
To protect and conserve the biodiversity of our forests, it is crucial to understand how species and their environments interact. Saproxylic beetles, which rely on deadwood, are a diverse group of insects with many different roles in forest ecosystems. They break down deadwood, releasing important nutrients back into the environment while also creating habitats for other species within the decaying wood.
"Understanding the needs of different beetle species by studying their traits can help us identify which types of environments may need to be restored or protected to preserve the diversity of saproxylic beetles," says Paulina Bergmark, a PhD student at SLU who led the study.
The study was conducted in both managed forests and so-called ecoparks, where the level of ambition regarding nature conservation is higher than in the surrounding forest landscape. Beetles were collected in 78 test plots over three years, and the beetles' various characteristics, such as their diet and preferred habitats, were then linked to environmental factors like the amount of deadwood and the types of surrounding forests.
"Our study shows that both the local amount of deadwood and the types of forests in the landscape are important factors shaping the composition of saproxylic beetle communities," says Paulina Bergmark.
The study indicates that beetles that prefer broadleaved trees require a substantial amount of broadleaved deadwood and landscapes rich in older broadleaf-rich forests. Beetles that favor coniferous trees need a high proportion of dead coniferous wood but seem to thrive in both young and old forests. Regarding the beetles' food preferences, both predators and fungivores (beetles that feed on wood-inhabiting fungi) show strong connections to old forests in the surrounding landscape.
“Our study helps us better understand which factors are crucial for preserving biodiversity in forests. By knowing how beetles that depend on deadwood are affected by their surroundings, we can develop more effective strategies to protect and restore forest environments. This is essential not only for conserving the beetles themselves but also for the entire ecosystems that rely on them,” says Paulina Bergmark.
The study was funded by the Oscar and Lili Lamm Foundation. The Swedish state-owned forestry company Sveaskog provided land for the experiments and contributed with data.
Paulina Bergmark, Joakim Hjältén, Johan Svensson, Wiebke Neumann, Anne-Maarit Hekkala. Trait-environment interactions of saproxylic beetles as a guide to biodiversity conservation strategies. Journal of Environmental Management, Vol 360 (2024) https://doi.org/10.1016/j.jenvman.2024.121080