Climatic signal in annual growth variation in damaged and healthy stands of Norway spruce [Picea abies (L.) Karst.] in southern Finland

Annual radial increment variation and its dependence on temperature and pre cipitation were studied in 13 severely damaged and 12 healthy stands of Nor way spruce [Picea abies (L.) Karst.] on mineral soil and peatlands in south ern Finland. An intervention analysis revealed that the presently dead tree s had experienced severe growth reductions since the late 1980s. Even thoug h annual growth variation between the stands was fairly similar, difference s in the relationship between radial growth and weather variation were foun d between sites. High temperature in May increased radial growth in the hea lthy stands. This was not observed in the damaged stands, where summer temp erature was negatively correlated with growth. In addition, high temperatur e during the previous summer decreased tree growth in next summer. Tree-rin g indices showed a strong positive correlation with June precipitation in t he damaged stands. Correlation of June precipitation and growth was much we aker in the healthy stands. This result suggests that the damage is connect ed to drought and is likely to occur at drought-sensitive sites. The findin g also fits in well with the fact that many of the damaged sites were rocky or stony.