Wood-Living Beetle Species and Communities in Swedish Forestry: Some Lessons for Conservation

Abstract

The papers in this thesis examine the diversity of wood-living beetles, a highly diverse group of conservation concern, in the context of southern Swedish forestry and forest management. Since the 19th century, industrial forestry and abandonment of traditional management has led to substantial changes in forest structure and characteristics in the region, with likely detrimental effects for many wood-living beetles. At the same time, management interventions such as different forms of thinning could benefit the group, by creating sun-exposed dead wood which is preferred by several species. In the first paper, an experimental set-up evaluated the 10-year effect of conservation-oriented thinning in oak-dominated (Quercus spp.) mixed forests. We documented a 33% increase in the number of woodliving beetle species associated with oaks, compared to unthinned reference stands. The second paper compared the wood-living beetle fauna of pre-commercially thinned Norway spruce (Picea abies) production forests with that of nearby unthinned woodland key habitats. Overall, the diversity of all wood-living species combined was similar, but lower for some groups, including red listed species, in thinned stands. The results indicate that conservation-oriented thinning can be an effective method of favoring this important organism group in oak-dominated forests over longer periods. In managed spruce forests, pre-commercial thinning may benefit some species but not primarily those of conservation concern.