Fig. 1From: Persisting bark beetle outbreak indicates the unsustainability of secondary Norway spruce forests: case study from Central EuropeDispersal of Ips typographus as indicated by amount of felled trees in forest compartments in year y relative to amount of trees felled in forest compartments in year y − 1. Such calculation was performed within nine distance categories with width of 150 m surrounding the compartments with felling in year y Back to article page