ABSTRACT: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)(2008)(2009)(2010)(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.

ABStRAct:The phenology of four deciduous forest tree species (Carpinus betulus L., Fagus sylvatica L., Quercus dalechampii Ten., Tilia cordata Mill.) was studied in a submountain beech forest stand in Central Slovakia. Two spring phenological phases -bud-burst and leaf unfolding as well as one autumn phase -autumn leaf colouring were monitored over the period of 13 years. The results documented interannual variability in the dating of phenological phases within the species, while the differences among the species were also revealed. Significant correlations (P < 0.05) were detected between the dating of leaf unfolding and air temperature; the coefficients of correlation (r) ranged from -0.86 (hornbeam and beech) to -0.92 (oak). Significant relationships were also revealed between cumulative precipitation amounts and timing of autumn leaf colouring phase (r-value ranged from -0.73 in oak to -0.81 in hornbeam). The trend analysis showed that the onset of phenological phases was slightly shifted to the earlier dates during the period of 13 years. However, the trends were not statistically significant. some tree species, e.g. beech (Gessler et al. 2007). On the other hand, we can expect a relatively positive effect -longer duration of the growing season (Chmielewski, Rötzer 2001). But it is not clear how these changes can affect the behaviour of trees when their regulatory mechanisms are disrupted.The aim of the present study is to analyze variability in the onset of selected vegetative phenological phases in four deciduous forest tree species in a submountain beech forest stand during the period of 13 years. Potential relationships between selected climatic factors and phenological phases were also studied. MAteRiAl And MethodS Study siteInvestigations were carried out in a submountain beech forest stand at the Beech Ecological Experimental Station (BEES), which is localized in the south-east part of the Kremnické vrchy Mts. (48°38'N, 19 o 04'E, 450-520 m a.s.l.). The study area is situated on a slope 5-15° oriented to the westsouthwest. The soil cover is skeletal Cambisol with moderate acid reaction and skeleton content ranging from 10 to 60% (Kukla et al. 1998 (Kontriš et al. 1993). The investigated area belongs to the moderately warm region and moderately warm and humid hilly land subregion (according to Lapin et al. 2002). The mean annual air temperature and mean annual rainfall totals are 6.8°C and 780 mm, respectively. On average, the coldest month is January (-4°C), while the warmest one is July (17°C). About 55% of the annual precipitation amount falls from April to September (Střelec 1992). More information detailing the BEES was described in papers published by Kodrík (1993), Barna (2004), Kuklová et al. (2005), Kellerová and Janík (2006). Phenological monitoring and meteo-dataPhenological observations were done according to slightly modified methodology used by the Slovak Hydrometeorological Institute (Slovenský hydrometeorologický ústav -SHMI 1996). Monitoring (for the period 1995-2007) usually start...

Two spring phenophases (bud-burst and leaf unfolding) of a parent stand and naturally regenerated undergrowth of European beech were observed in conditions under different stand density over the last 10 years. The results proved the unequal onset of phenophases of the parent stand individuals in relation to their sociological status. In the case of codominant and dominant trees the delay of 2-5 days was observed in comparison with subdominant trees. The influence of the parent stand structure on the onset of the undergrowth phenophases was also observed. The onset of phenophases differed by 2-20 days among individuals grown under different density of the parent stand. The onset and course of phenophases also differed between the years. The trend of the average onset of leafing in the period 1995-2004 shows a shift to earlier dates by about three days. Temperature summation of average daily temperatures with the base temperature of 8°C, in the framework of the model predicted bud-burst of beech, showed the lowest variability in comparison with other temperatures.

No abstract

At present, temperate forest ecosystems are endangered by both abiotic and biotic factors. The effects of abiotic components, e.g., meteorological variables, are constantly studied. However, the detailed mechanisms affecting the phenology of plants are still unknown. Two meteorological variables (air temperature and cumulative precipitation) were analysed for the period from 1995 to 2020 in order to determine which factor which has a more significant effect on onset of the full-flowering (FF) phenophase. A set of nine forest herbs, representing different phenological groups from the viewpoint of flowering, was examined (early spring: Petasites albus and Pulmonaria officinalis; mid-spring: Carex pilosa and Dentaria bulbifera; late spring: Fragaria visa and Galium odoratum; early summer: Veronica officinalis; mid-summer: Mycelis muralis; and late summer: Campanula trachelium). Temperature-sum requirements and temporal trends in the onset of FF were also studied. The research conducted at the Ecological Experimental Station in the Kremnické vrchy Mountains (central Slovakia) at an altitude of 500 m asl. Our results show that the air temperature correlated more significantly with the date of onset of FF (r > 0.6, p < 0.001) than with precipitation. On average, the air-temperature sums, calculated for the threshold temperatures of 0 °C and 5 °C, increased from 142.9 °C (Petasites albus) to 1732.9 °C (Campanula trachelium) and from 223.4 °C (Petasites albus) to 1820.8 °C (Campanula trachelium), respectively. Temporal trends in the onset of FF over the last 26 years confirm shifts to earlier dates for most species (excepting early spring Petasites albus). In spring flowering species, shifts ranged from 2 days (0.07 day/year) for Pulmonaria officinalis to 8 days (0.30 day/year) for Carex pilosa. As for summer species, the onset of flowering shifted more significantly to earlier dates—from 7 days (0.27 day/year) for Campanula trachelium to 12 days (0.46 day/year) for Veronica officinalis. The observed trends were statistically significant (p < 0.05) for five examined species (Carex pilosa, Dentaria bulbifera, Fragaria vesca, Veronica officinalis and Mycelis muralis).