Observation of climatic parameters and plant phenology in the international phenological garden of Klaipėda University Botanic Garden, Lithuania

The phenology of plants varies greatly over broad geographic gradients, according to climate zone and vegetation type. Phenological records were collected from 2007 to 2024 at KUBG, which is one of the 89 gardens belonging to the International Phenological Gardens (IPG No. 151). The garden is located in Western Lithuania, close to the Baltic Sea coastline (about 3.5 km) (55°42′40″N 21°7′50″E). For the analysis, only 5 species were chosen. The average annual air temperature in Klaipėda is 7.9 °C. The coldest period is January-February, where the average air temperature is -1.0 °C. The warmest period occurs in July-August (aver. 18.2 °C). The autumn temperature of the last season had the most influence: the strong correlation was with leaf unfolding of all trees, as well as strong or moderate correlation with the beginning and full flowering of Salix viminalis and Syringa ×chinensis. Only the precipitation of last autumn and precipitation of January-February had a statistically significant influence on spring phenophases. Salix viminalis had the longest vegetation period (224 days) while the Sambucus nigra had the shortest one − 187 days. Precipitation during January-February had a strong or moderate positive correlation with the leaf unfolding of all examined trees, as well as a moderate positive effect for beginning and full flowering of Syringa chinensis. The summer and autumn temperature had a negative relation for both vegetation periods. The strongest correlation appeared between summer temperature and vegetation period of Corylus avellana and Sambucus nigra. These findings highlight the importance of long-term phenological monitoring as a sensitive indicator of climatic variability and as a tool for ecosystem management and climate adaptation strategies.