Does the provenance make the difference? Results from progeny tests of pedunculate oak (Quercus robur L.) and Norway spruce (Picea abies (L.) Karst) in Baden-Wuerttemberg, Germany

The present study addresses the question whether provenances of pedunculate oak (Quercus robur L.) and Norway spruce (Picea abies (L.) H. Karst) from the German federal state of Baden-Wurttemberg differ with respect to their growth properties. For this purpose, we gathered and analyzed data from common garden experiments. These included one progeny test with pedunculate oak, established in 1992 and one for Norway spruce, established in 1987. The statistical analysis was based on tree height, diameter at breast height (dbh) and mortality rate. Regarding mortality, significant differences among provenances were revealed at one single site (plot) within each species. By analyzing mortality across all plots, significant differentiation was observed in pedunculate oak only. Significant differences in height growth among provenances were found in the two species, both within and across sites. Provenances with excellent height growth across sites were found in both species: for instance, provenance 'Calw-Hirsau' for Norway spruce and 'Biberach' for pedunculate oak. With respect to dbh, significant differences between provenances were found only in pedunculate oak. A relationship between altitude of origin and height growth was found mainly in Norway spruce. Provenances from lower altitudes tended to perform better. These differences were more pronounced in Norway spruce. In pedunculate oak, this tendency was not significant at sites with medium and higher altitude. Provenances from high altitudes - e.g. provenance Blaustein - performed well there, despite their below-average height growth elsewhere. We interpret this as an adaptation to the local site conditions.