Höjdförflyttning av granprovenienser i norra Sverige

Provenances of Norway spruce (Picea abies (L.) Karst.) are generally transferred from lower latitudes and elevations to areas where the local seed production is insufficient and with the goal to increase volume production because growth cessation in the fall is induced later in northward transferred material. The aim of this study was to analyze the effect of altitudinal transfer on volume production and survival in three mature field trials located at 420, 500, and 620-650 m a.s.l. in northern Sweden. A total of 13 provenances from latitudes between 61 and 64.5 ºN and altitudes between 50 and 500 m a.s.l. were included. The trials consisted of 2-4 blocks and 8-9 provenances planted in plots of 10x10 or, in one trial, 12x20 trees. In the field inventory diameter at breast height and stem damage were recorded for all trees and height measurements were taken on 4-5 trees per plot. The volume of the selected trees was used to obtain a secondary volume function for each trial. In the statistical analysis no significant differences between the provenances were found for volume per ha and damage frequency and severity in 2003. Survival data were analyzed from 1956, 1970, and 2003. The latitudinal origin of the provenance influenced survival in the trial at the lowest elevation in 1956 and 2003, but in the intermediate elevation trial no correlation was found between survival and latitudinal or altitudinal origin. In the trial at the high elevation site, close to the tree line, survival decreased with increasing altitudinal transfer in 1956 and 1970, but the trend was not significant in 2003. At such extreme sites seed sources from much lower elevations should be avoided, but on sites with more favorable conditions they can probably be used without risk for increased mortality