Fig. 4From: Persisting bark beetle outbreak indicates the unsustainability of secondary Norway spruce forests: case study from Central EuropeInfestation of forest stands in 2000–2004 in the study region as indicated by ordinary kriging. f shows the position of the average anisotropical ellipse for years 2002–2004. The ratio and angle of the anisotropical ellipse were preserved but not the sizeBack to article page