Data from: Varying selection differential throughout the climatic range of Norway spruce in Central Europe

Predicting species distribution changes in global warming requires an understanding of how climatic constraints shape the genetic variation of adaptive traits and force local adaptations. To understand the genetic capacity of Norway spruce populations in Central Europe, we analyzed variation of tree heights at the juvenile stage in common-garden experiments established from the species’ warm-dry to cold-wet distribution limits. We report the following findings: first, 47% of the total tree-height variation at trial sites is attributable to the tree populations irrespective of site climate. Second, tree height variation within populations is higher at cold-wet trial sites than at warm-dry sites and higher within populations originating from cold-wet habitats than from warm-dry habitats. Third, for tree ages of 7 to 15 years, the variation within populations increases at cold-wet trial sites, whereas it remains constant at warm-dry sites. Fourth, tree-height distributions are right-skewed at cold-wet trial sites, whereas they are non-skewed but platykurtic at warm-dry sites. Our results suggest that in cold environments climatic conditions impose stronger selection and probably restrict the distribution of spruce, whereas at the warm distribution limit, the species’ realized niche might rather be controlled by external drivers, i.e. forest insects.