Saproxylic beetles in Swedish boreal production forests in relation to local and landscape factors

Abstract

AbstractBoreal forests undergo rapid transformation from more or less intact states to even-aged production stands, due to the expanding clearcutting practice. Deepened knowledge on how species diversity and composition vary with local resource availability, such as dead wood, as well with remaining never clearcut forest (having long continuity = ‘continuity forest’) in the surrounding landscape, is essential for the formulation of conservation strategies. In each of six 15 × 15 km study areas in mid-boreal Sweden (12 000 km2) we sampled saproxylic beetles through sieving of bark from Picea abies logs in early stages of decay with bark still attached, within 5 production forests and 5 woodland key habitats (biodiversity hotspots, used as reference; ‘WKH’). A total number of 5147 individuals and 78 taxa were found. Beetle diversity related positively to the local factor of sieved bark area, while the share of continuity forest in the surroundings (5 km buffer; varying 5 − 29% among study stands) was less important, and even showed negative relationships. Species richness was higher in > 60 years old than 0–60 years old production forests but we did not detect a change with age in species composition. The production forests > 60 years old and WKH were similar regarding species richness and composition. WKH had more species of conservation concern than the production forests.