THE INFLUENCE OF CLIMATE CHANGES ON THE FLOWERING START OF WOODY PLANTS IN THE STEPPE ZONE OF UKRAINE

Introduction. According to well-known climatologists, the Earth’s air temperature increased by 0.3–0.6 °C in the 20th century, and this period of warming is quite long-term. Air temperature changes in the Steppe zone of Ukraine occur approximately as they do on the planet as a whole. An increase in air temperature causes shifts in the seasonal rhythm of development in plants of various natural habitats, which can be considered as one of the bioindicators of climate change. Spring phenological processes are more sensitive to changes in the temperature regime, so they experience the strongest transformation compared to other seasons. The most informative phenophase regarding the impact of climate change on plants is the phase of the beginning of flowering. Woody plants are an important component of optimizing urban landscapes and maintaining their diversity in the presence of climate change requires adaptation based on their genetic and phenotypic variability. Based on this, it is relevant to study the peculiarities of the adaptation of their phenorhythms to the modern climatic factors of the Steppe zone of Ukraine, which are aggravated by the action of air pollutants from the enterprises of the Kryvyi Rih region. Aim. To study of the influence of global climate changes at the beginning of the flowering of woody plants in the conditions of an industrial city in the Steppe zone of Ukraine. Methods. Fixation of the date of the beginning of flowering was carried out according to the method of phenological observations in botanical gardens. The study of climatic changes during 1997–2023 was carried out according to the data of the Internet resource (Weather website – http://rp5.ua). The equation of the trend line and the reliability of their approximation (R2) were calculated using the Excel 2016 program. The analysis of the non-parametric Spearman correlation coefficient was performed in the Excel 2016 program. Main results. The results of the analysis of meteorological data in Kryvyi Rih for the period 1997–2023 recorded a gradual increase in the average annual temperature by 1.2 °C, which led to earlier periods of accumulation of positive, effective and active air temperatures for plants (above 0, 5, 10 °C, respectively ) in the spring period. It was proven that in connection with this, the flowering phase of woody plants had shifted to earlier periods. The trend line for the beginning of flowering during 1997–2023 shows a significant shift to earlier dates with the highest approximation value for Tilia cordata. When comparing the average multi-year dates, the beginning of flowering in 2010–2023 compared to 1997–2009 is earlier for Tilia cordata by 5.4 days, for Acer platanoides, Crataegus submollis, Forsythia europaea, Spiraea × vanhouttei this value is from 0.8 up to 1.4 days. Correlation analysis between the beginning of flowering and the sum of temperatures revealed the greatest dependence on temperatures above 5 °C – this indicator is reliable in Acer platanoides, Crataegus submollis, Tilia cordata. The amount of precipitation decreased during 1997–2023 by 27%, which is especially critical during droughts, usually in July–September. With the aggravation of such climatic changes, the influence of summer-autumn droughts on the physiological state of plants will deepen, the number of dust storms, the intensity of evaporation, abnormal temperature manifestations, etc. will increase. Such climatic manifestations are able to make significant adjustments to the range of woody plants used in the landscaping of industrial cities in the Steppe zone of Ukraine. In the future, desertification of this region, displacement of natural zones, which will affect the composition of tree vegetation, is possible. The gradual change in climatic conditions involves the revision of the existing list of species and varieties prospective for introduction into the steppe region, the expansion and change of the range of selection criteria.