Phenology of common beech (Fagus sylvatica L.) along the altitudinal gradient in Slovakia (Inner Western Carpathians)

The onset and course of selected vegetative phenological phases of beech along the altitudinal gradient in Slovak Republic were studied. Observations were done in the Burda Mts. (200–300 m a.s.l.), Kremnické vrchy Mts. (500 m a.s.l.) and in the Poľana Mts. (900–1,000 m a.s.l., 1,200–1,400 m a.s.l.). Selected spring phenological phases (budburst and leaf unfolding) as well as autumn phenological phases (autumn colouring and leaf fall) were investigated over the period of 5 years (2007–2011). The earliest onset of spring phenological phases during the period of study was found at the lowest-lying sites in the Burda Mts. By contrast, the latest one was observed at the uppermost site in the Poľana Mts. The dynamics of autumn phenological phases had the opposite course compared to spring phenophases. The earliest onset, observed in the uppermost locality in the Poľana Mts., was gradually delayed with decreasing altitude. The phenological gradient, expressing a shift in the onset of spring phenophases along the gradient, reached the mean values of 2.83–3.00 days per 100 m of an increase in altitude. In the case of autumn phenological phases the gradient ranged from –1.00 to –1.78 days per 100 m. On average, the growing season of beech lasted from 128 to 181 days along the altitudinal gradient. Significant correlations (P < 0.001) were calculated between the date of the onset of phenophases and altitude.