ZLV Online

Abstract

Phenology of three selected deciduous forest tree species (Carpinus betulus L., Tilia cordata Mill. Quercus dalechampii Ten.) was studied in a submountain beech forest stand in central Slovakia. Two spring phenological phases – bud-burst and leaf unfolding 50% as well as two autumnal phases – leaf discolouration 10% and 50%, respectively were monitored over the period of twenty years (1995–2014). Analysis of the air temperature showed its increasing values mainly in the period from April to August. On the other hand, the values of cumulative rainfall totals for the period from May to August had not clear trend. They were strongly volatile among the years with oscillation around the long-term average. Results of phenological research referred to the interannual variability in dating of phenological phases within the species, also the differences among the species were found. The significant correlations (P < 0.05) were detected between dating of leaf unfolding and air temperature; the coefficients of correlation (r) moved from 0.83 (hornbeam) to 0.90 (oak). Correlations between cumulative rainfall totals and timing of autumnal leaf discolouration were significantly lower. Trend analysis revealed temporal changes in onset of the phenophases. Average onset of spring phenological phases was shifted to earlier dates, but trend in onset of the autumnal phenophases was the opposite. Onset of leaf discolouration was shifted to later dates, so vegetation period was extended. Among the trees, the dynamics of leaf unfolding did not show significant temporal changes, only hornbeam was the exception.