Evaluation of physiological and health state of Norway spruce plants with different growth rate at juvenile stage after outplanting at mountain locations

Norway spruce (Picea abies [L.] Karst.) seedlings grown from seed originating from high mountain locations (8th forest altitudinal zone - Norway spruce vegetation zone 1,000-1,250 m a.s.l.) show higher growth variability than seedlings from populations adapted to more favorable conditions at a lower altitude a.s.l. Seedlings smaller than 8 cm in height were usually culled during sorting before transplanting (in common nursery practice) regardless of the fact whether it was not planting material from high mountain locations. This paper presents the results of the physiological and health state of 16 year old spruce stands established by outplanting of specifically sorted planting material (comprising also slowly growing seedlings) on the research plot Pláň (Krkonoše Mts). Differences among variants in water losses during drying were relatively small and statistically insignificant due to high individual variability; nevertheless, they indicate a certain positive trend in plants with slower growth dynamics in the nursery. Differences in chlorophyll fluorescence among the variants were statistically significant. The trend of higher frost hardiness in the "small" variant was obvious again. The health status results document the initial assumption of very good adaptation to adverse mountain conditions in trees grown from seedlings characterized by slow growth in a nursery. The results of evaluation of physiological parameters and health status confirm a hypothesis that plants with the initial slow growth are a stable component of the population spectrum of mountain spruce trees. The results document good preconditions for the establishment of vital and stable stands when the entire growth spectrum of planting stock and particularly of plants produced from originally slow-growing seedlings is utilized.