Target-tailored forest damage inventory

An annual monitoring of the most important sources of forest damage is carried out by the Swedish National Forest inventory (NFI). The Swedish NFI contributes data to, for example, the European cooperation programme ICP Forests and to Forest Europe.

Although the Swedish NFI is an objective and uniform inventory of forest damage in Swedish forests at national and regional scales, less common or less widespread occurrences of forests pests and pathogens are difficult to survey solely through large-scale monitoring programmes. There is a need for complementary tailored inventories to facilitate timely delivery of relevant information. TDFIs are developed to give a rapid response to requested information on specific damage outbreaks. The TDFIs are carried out in limited and concentrated samples, with flexible but robust methods and design.

Since 2007 inventories have been carried out to assess the damage caused by resin top disease (Cronartium flaccidum), ash tree disease (Chalara fraxinea) and bark beetle attack (Ips typographus; Polygraphus poligraphus) on Norway spruce. During 2015 and 2016 a repeated inventory of bark beetle attacks in older spruce forests is carried out in the county of Västernorrland and the eastern part of the county of Jämtland. In 2020 an inventory of elm in Gotland was carried out. In autumn 2020 and 2021 and inventory of damage caused by European barkbeetle (Ips typographus) was carried out. 

The results from the inventory in 2021 show a total volume of just over 8 million m³sk of Norway spruce damaged by European spruce bark beetle. The total affected volume is estimated at about the same level as last year, but it seems that the center of the spruce bark beetle attacks in 2021 has shifted north. Of the total volume, there were 4.3 million m³sk in Svealand and 3.9 million m³sk in Götaland. The largest volumes were found in northeast Götaland and eastern Svealand.  The inventory also shows that 6.7 million m³sk damage spruce was left in forest and 1.6 million m³sk was harvested. This means that large volumes of damaged spruce have been removed from the forest, but also that large volumes remain in the forest, which implies that the risk of major attacks of spruce bark beetle persists for the coming years.