The map “Skadeprosent utbrudd 1970-tallet” (Damage level during the 1970’s outbreak) shows percentage classes of the Norway spruce growing stock that were killed in different municipalities during the Ips typographus outbreak in the 1970’s. The colors in the map increase in intensity from green and light yellow to dark red with increasing damage level (see “Tegnforklaring” at the top of the menu for details).
The rationale for showing this map is that areas suffering extensive damage in the 1970’s may have a greater risk of bark beetle damage also in the future. Spruce forests on certain types of well-drained bedrock proved to be particularly vulnerable to attack in the 1970’s. This applies, for example, to forest areas in Porsgrunn and Larvik. Areas with extensive damage in the 1970’s may also have other characteristics predisposing them to bark beetle outbreaks.