The Norway spruce is economically important tree species in the Baltic Sea region, covering large areas and being productive in pure plantations. The species is often regenerated with planting. It is important to choose not only productive, but also robust reproductive material with good adaptability in changing climate, hardiness and quality traits. The use of appropriate transferred provenances can be an option to increase forest productivity at final-harvest moment. Thus, it is necessary to know long-term fitness of different seedlots to increase climate change adaptation capacity. We examined two provenances trials in Western and Eastern Latvia at the age of 34 and 29 years, respectively. We assessed effect of provenance on growth performance, stem quality, and budburst time. In the milder climate of Western Latvia, superior growth showed certain northward-transferred, later flushing provenances from the Ukrainian Carpathian Mountains and Lithuania, resulting in by up to 35% higher basal area than the trial mean. No advantages were observed for early flushing Western Russian seedlots facing southward transfer. Latvian provenances showed variable performance regarding productivity and stem quality. In the harsher climate of Eastern Latvia, selection of productive local seedlots seemed reasonable option due to higher areal productivity and relatively lower proportion of trees with stem defects comparing with transferred material.

Keywords: long-term provenance study; flushing time; forking; seed transfer; adaptation ability