The Influence of Climate Change on the Response of Introduced Plants in the Conditions of Southern Siberia

The aim of this study was to conduct a statistically significant assessment of the phenological reactions of perennial medicinal plants in the south of Tomsk Oblast coordinated with indicators of average daily and monthly temperatures. The work used classical research methods that were relevant and unchanged over fifty years of observation. The observations were carried out for fifty years on introduced plants that entered the period of generative development in 1972, after the individuals entered the postgenerative period of development and the cessation of generative function. The observations were carried out on their reproductions of the original individuals formed under the conditions of the south of Tomsk Oblast. The objects of research were species of medicinal plants introduced under the above conditions in the Siberian Botanical Garden: Althaea officinalis L., marshmallow, a perennial herbaceous plant of the Malvaceae family and Tanacetum vulgare L., tansy, a perennial herbaceous plant of the Asteraceae family. The phenological responses of perennial medicinal plants were studied using standard ground-based observational techniques from 1972 to 2022. The correlation analysis with the calculated Pearson correlation coefficient (p < 0.005) was used to identify the relationship between average daily temperatures and the timing of phenophases. When analysing the results of meteorological monitoring of average monthly temperatures (conditionally divided by decades), reliably significant increases in average temperatures in the spring and autumn months were established: April from 1.3 to 4.5 °C over the last decade, August from 14.6 to 16.4 °C, October from 0.4 to 2°C. In other cases, no clear trend towards an increase in average monthly temperatures over decades was found. When analysing changes in precipitation over decades, the most dramatic ones were noted in the summer months; no statistically significant trend toward an increase or decrease in precipitation over decades was established. As a result of this study, the average timing of the onset of phenophases of Tanace-tum vulgare L., Althaea officinalis L. individuals over fifty years under the conditions of an introduction experiment was determined. When analysing the timing of pheno-logical events for T. vulgare in the south of Tomsk Oblast, it was established that the species goes through a full cycle of seasonal development with all phases successfully implemented. The average timing of the onset of vegetation in the south of Tomsk Oblast is at the beginning of May and is associated with a steady increase in air temperature above 0 °C, budding - at the beginning of July, flowering occurs at the end of July, fruiting is noted at the end of August. Using the standard deviation indicator, an attempt was made to establish a connection between the plasticity of the studied species and their phenological responses to climate change. The periods from 1972 to 1981 and from 2012 to 2022 were characterised by the greatest fluctuations in the standard deviation indicator for all phases of phenological development. However, over the entire history of observations, the greatest changes in the timing of the onset of phenophases were noted for the flowering phase: minus 7 days per 10 years in the first decade and minus 5 days per 10 years in the last decade. The timing of the onset of the budding phase also shifted by 5 days over the first decade. A. officinalis under the conditions of the south of Tomsk Oblast goes through a full development cycle; however, in some years, the fruiting process cannot be completed successfully, the seeds do not always have time to ripen, which can explain the high values of the standard deviation and deviation from the average long-term date of the onset of the phenological event. All phases of development were marked by significant fluctuations, and the phases of fruiting and budding - to the greatest extent. Spring regrowth under the conditions of Tomsk Oblast for A. officinalis L. begins at the end of May and is associated with a stable transition of temperatures through 5°C, budding begins in late June-early-mid July, flowering is noted in late July-early August, end of August- beginning of September. The most conservative characteristic in terms of standard deviation is the growing season during all the analysed periods; the largest fluctuations were noted for the fruiting phase in the decades 1981-1990 and 1991-2000. Over the entire history of observations, the greatest changes in the timing of the onset of phases were noted for budding: minus 13 days for the first decade and plus 14 days for the period 1991-2000 and the fruiting phase: minus 11 days for the first decade and minus 15 days for the period 1991-2000. Both species were characterised by significant fluctuations in the timing of pheno-logical events in the first decades of the beginning of the introduction experiment, perhaps this is due to actively ongoing adaptation processes or individual reactions to the conditions of the growing seasons. For T. vulgare, a negative correlation was established between temperature characteristics and the onset of the flowering and fruiting phases. For A. officinalis, a negative correlation was established between the average daily temperature and the onset of the vegetation and budding phases. The established features of the rhythm of growth and development showed the difference between the reactions of the species adapted to natural and climatic conditions of the cultivation region (T. vulgare) and the species weakly resistant to the conditions of the region (A. officinalis). In the first case, average daily temperatures for flowering and fruiting phases were of importance, in the second case - average daily temperatures of the beginning of the growing season. When analysing average monthly temperatures for the period 1972-2022, a significant increase in average temperatures of spring and autumn months were found. The article contains: 2 Figures, 2 Tables, and 20 References. The Authors declare no conflict of interest.

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