Dynamics of Phenological Parameters in Some Lilac Species in a Changing Climate

Changes in the seasonal development of lilac species cultivated in the South-Ural Botanical Garden–Institute (Ufa, Russia) have been analyzed based on data collected in 2005–2010 and 2015–2020. Eleven lilac species that have already reached the generative phase are examined. All studied plants had been grown from seeds received from other botanical gardens in the 1950s–1960s. Phenological observations of lilac species are performed on an annual basis and cover nine phenological phases. The start time of the initial (bud opening and beginning of sprout growth) and final (leaf fall) phases of the growing season significantly depends on the weather conditions of a particular year. The role of species-specific (genetic) features at the beginning of seasonal development is insignificant (the species start vegetating simultaneously), but, starting from the flowering phenophase and until the end of the growing season, their role increases dramatically. Year-to-year differences in the middle of the growing season are of secondary importance. The following characteristics of phenological development rhythms are persistently dependent on meteorological fluctuations in different years: flowering time and vegetation duration. The succession of phenophases passed by different species does not change from year to year. Compared to the first decade of the 21st century, the growing season in the second decade begins later (by 4 days on average) and ends earlier (by 8 days on average), and flowering also begins 4 days later on average. In 2015–2020, flowering time decreased in the studied lilac species by 5–6 days when compared with the period 2005–2010. The vegetation duration decreased by 12 days on average. The above-listed phenomena are apparently caused by climatic changes in the Bashkir Cis-Ural region.