Infestation symptoms as indicators of a sustained bark beetle outbreak in conserved and managed Norway spruce forests in south-eastern Finland

377-391

e-journal

200212770

European spruce bark beetle (Ips typographus L., SBB) infestations are extending in northern Europe due to increases in temperature and drought, which increase the risk of outbreaks in Norway spruce (Picea abies L.) forests. The severity of SBB damage may be decreased by timely detection and management measures. In this study, we analysed the SBB infestation levels of trees, the overall SBB damage at the stand level, the relationship between SBB damage and stand characteristics, and the effect of an outbreak over time on the volume and basal area in managed and conserved areas. We visually observed SBB symptoms at the stem level (entrance-exit holes, resinous flows, bark damage) and crown level (defoliation, discoloration) in 60 sampling plots in south-eastern Finland. These plots were established in an SBB outbreak area triggered by a severe wind disturbance in August 2010. Data were collected in 2014–2017 in conserved areas and in 2019–2021 in both conserved and managed areas. The results showed that in conserved areas, 70% of the trees were already highly infested in 2015, reaching 90% in 2017.
Keywords: Forestry; Forest Ecology; Forestry Management; Invasive Species; Tree Biology; Boreal Ecology