Temporal variability of spring phenological phases and diameter increment of Norway spruce ( Picea abies /L./ Karst.) provenances

Abstract

The presented paper analyses temporal variability of the beginning, end, and the length of growth, and of the selected spring phenological phases of Norway spruce. The experiment was performed on three provenances of Norway spruce (Picea abies /L./ Karst.) originating from the orographical unit of Volovské vrchy, and growing in Borová hora arboretum, during the three years 2010, 2011 and 2012. The examined provenances were selected on the base of the elevation gradient from three elevations: 500 m a.s.l., 750 m a.s.l. and 1,100 m a.s.l. Tree stem circumference changes were continuously measured, and spring phenological phases were assessed. Our results proved that a significant temporal shift in the onset of the phenophases to a later period occurs in provenances originating from higher elevation. We found that during the period from 2010 to 2012, the sum of the effective air and soil temperatures needed for the onset of the phenological phases decreased from one year to another. The highest effective sums of air and soil temperatures were required for the provenance originating from the highest elevation (1,100 m). The analysis of diameter increment showed that the lowest increment value equal to 4.35% was recorded in April 2010, while the increment in April 2011 was 13.11% and in 2012 it was 10.09% of the overall increment of the stem diameter in growing season. This was caused by the later onset of spring phenophases in April 2010 caused by lower air temperatures in this month.