Clear-cutting has a long-term impact on red-listed saproxylic beetles in boreal forests with deadwood diversity as the main driver

The widespread introduction of clear-cutting to Fennoscandia in the 1950s led to fundamentally altered forest structure and reduced volume and quality of deadwood – a key resource for saproxylic organisms. As previously clear-cut forests now approach economic maturity, the long-term ecological effects of this management practice on saproxylic beetle communities become measurable. We sampled beetles using flight interception traps in 12 paired Norway spruce forest stands in southeastern Norway: one previously clear-cut and approaching maturity, and one never clear-cut (near-natural), but with otherwise similar conditions. We found that clear-cutting negatively impacted the richness and abundance of red-listed species. In addition, we found weak evidence for the effect on species composition. The total saproxylic beetle richness, abundance and within-stand beta diversity were similar in the two forest management types. Both red-listed and total saproxylic beetle richness were positively associated with deadwood diversity at the stand scale. Our findings underscore the importance of preserving near-natural forests as refugia for red-listed saproxylic beetles, while highlighting the need to enhance deadwood diversity and structural complexity in managed forest stands to better support saproxylic biodiversity. • Of all beetle species caught in the study, 63 % were saproxylic. • Red-listed species were negatively affected by historic clear-cutting. • Deadwood diversity was driving total and red-listed beetle diversity. • Near-natural forests with low deadwood diversity may host low saproxylic richness.