Wood-living beetle diversity is enriched by surrounding broadleaf forest in a conifer forestry landscape

Humans have drastically changed many of the world’s forests since the industrial revolution, with northern European forests among the most affected. Research is needed on consequent effects on forest biodiversity. Here I focus on the conservation-relevant wood-living beetles. Whilst previous studies have examined the effect of local stand characteristics on beetle diversity, the influence of the surrounding landscape on alpha diversity may potentially be more important.

The aim of this study is to judge the influence and scale of effect of four landscape variables (broadleaf forest volume, area of mature forest, area of conservation forest, area of clear-cut) on alpha diversity of wood-living beetles as a whole, and ecological groups reflecting potentially differing dispersal ecologies (fungivores, wood consumers, predators, red-listed species).

The landscape variables were analyzed at three scales (within 250, 1250 and 2500 m radius) and related to wood-living beetle diversity sampled using flight interception traps in 73 managed and unmanaged forest stands in the conifer forestry dominated hemiboreal landscape of south-central Sweden.

Wood-living beetle diversity as a whole was positively associated with broadleaf volume at the 2500 m scale, with a weaker association for fungivore diversity at a varying scale. Surprisingly, both predator diversity (varying scale) and red-listed diversity (2500 m scale) was weakly negatively associated with mature forest.

The results highlight the importance of broadleaf trees for the diversity of saproxylic beetles in conifer-dominated forestry landscapes. Further, research and management should more closely consider contrasting responses between species with potentially differing dispersal ecologies, and at different scales.