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Conference paper, 2009

The spruce bark beetle outbreak in Sweden following the January-storms in 2005 and 2007

Långström, Bo; Lindelöw, Åke; Schroeder, Martin; Björklund, Niklas; Öhrn, Petter

Abstract

In January 2005, southern Sweden was struck by the largest storm-felling that ever has been recorded in Sweden. During 8-9 January, wind speeds exceeding 30 m/s were recorded over large areas in Götaland, southern Sweden, resulting in huge areas of storm-felled forests. The Swedish Forest Agency estimated that 75 million m3 had been damaged (broken or uprooted) during the storm. More than 4 million hectares were affected by the storm and 272 000 ha were classified as damaged or severely damaged. In some areas, volumes corresponding to up to 10 years annual cuts were damaged and averages volumes of damaged forests ranged from 65 to 75 m 3 per ha. Ca 80 % of the wind-felled trees were Norway spruce, 15 % were Scots pine and the rest, mainly broad-leaved species (Anonymous 2006). Considering the large volumes of damaged spruce, it was clear that there was an obvious risk for subsequent outbreaks of the spruce bark beetle (Ips typographus L., Col. Scolytinae). Hence large efforts were made to clear up the storm-fellings as soon as possible, in order to save timber values and to prevent a build-up of bark beetle populations. As will be seen below, however, large volumes of spruce remained in the forest over the summer 2005 and some was still suitable to the beetles in spring 2006, resulting in increasing beetle populations and tree mortality. A second storm-felling took place in partly the same area on 12 January 2007, when ca 12 million m 3 , mainly spruce was downed. Massive efforts were made to salvage the fallen timber before beetle flight in spring 2007, but many trees remained in the forest over the summer, producing new beetles. This presentation summarizes the forest protection situation in southern Sweden after the January-storm 2005, i.e. we describe how the fallen trees were taken care of, how the spruce bark beetle situation has developed, and discusses some of the control measures taken to counteract tree mortality.

Keywords

Ips typographus; Spruce bark beetle; Storm-felling; Gudrun; Outbreak

Published in

Title: Insects and Fungi in Storm Areas edited A. Kunca and M. Zubrik
ISBN: 978-80-8093-100-1
Publisher: National Forest Centre

Conference

Proceedings of the 9th workshop of IUFRO WG 7.03.10 on Methodology of Forest Insect and Disease Survey in Central Europe, 15-19 September, 2008, Slovakia