The diploma thesis focuses on long-term observation of phenological manifestations of selected main farm trees in the Great Fatra National Park. The research took place on monitoring plots, which were established near the natural monument Majerová skala. Six monitoring plots were established in this locality, on which the monitored woody plants, lean ash (Fraxinus excelsior L.), mountain maple (Acer pseudoplatanus L.) and beech (Fagus sylvatica L.) were located. The monitoring areas are established in an altitude transition of 100 altitude meters on the western exposure of the slope leading from Majerova skala. Phenological phases were recorded during the years 2016 - 2019. During the year, five generative phenophases and four vegetative phenophases were observed. In addition to the observation of phenological phases, the air temperature and relative humidity were also recorded for four years. Meteorological data were recorded at two meteorological stations (630 m and 1130 m a. s. l.). The measured meteorological data were processed and compared with the onset of phenological phases in the monitoring area. The research focused on the inverse character of the valley, which manifested itself during several years of observation. It was also a question of determining the influence of meteorological data on the manifestations of phenological phases of selected forest tree species.