Response of old‐growth montane Picea abies (L.) Karst. forest to climatic variability in northern Sweden

summary Repeat photography and tree ring analyses were used to investigate structural change, 1938–88, of an old growth and high elevation Picea abies (L.) Karst. forest in northern Sweden. The forest, initially moribund, senescent and top‐broken, regenerated broken tops and apparently gained in vigour. Up to the 1930s this progressive change was pre‐dated by an increase of annual increment growth, which subsequently declined until the 1980s, The tree‐ring response concurs with the general course of summer temperature while canopy processes appear to lag behind. The study stresses the importance of phenotypic plasticity for Long‐term behavior of marginal J spruce forest. It is also evident that canopy development is not a fully predictable ageing process, but to some extent dependent on climatic variability.