This study presents the results of the development of numerical models for predicting the timing of apricot flowering, including using experimental data on the emergence of plants from a state of deep dormancy. The best results of approximation of the process of accumulation of the necessary cooling in the autumn–winter period were obtained using the sigmoidal function. Models that take into account the combined effect of temperature and photoperiod on the processes of spring development showed a high accuracy of the process of accumulation of thermal units. Based on the results of testing, two models were selected with an accuracy of 3.0 days for the start of flowering and the absence of a systematic bias, which can be considered a good quality assessment These models describe well the interannual variability of apricot flowering dates and can be used to predict these dates. The discrepancy is no more than 2–4 days in 87–89% of cases. Estimates of the timing of flowering and the end of deep dormancy are very important for increasing the profitability of fruit production in the South of Russia without incurring additional costs, by minimizing the risks associated with irrational crop placement and the selection of varieties without taking into account the specifics of climate change. When constructing a system of protective measures and dates of treatments, it is also necessary to take into account the calendar dates of the shift in the development of plants.

The increase in the frequency and intensity of hazardous hydrometeorological phenomena is one of the most dangerous consequences of climate instability. In this study, we summarize the data on severe weather phenomena using the data from 23 meteorological stations in Crimea from 1976 to 2020. Particular attention was paid to the precipitation phenomena descriptions. For the last 45 years, a significant positive trend of interannual variability of the annual occurrence of severe weather phenomena was estimated to be +2.7 cases per decade. The trend for severe precipitation phenomena was estimated to be +1.3 cases per decade. The probable maximum annual daily precipitation as a quantitative indicator of hazardous events was estimated for each station by using both the stationary and the non-stationary GEV models. For at least half of the meteorological stations, a non-stationary GEV model was more appropriate for the estimation of the precipitation extremes. An analysis of the main synoptic processes that drive severe weather phenomena of precipitation was carried out. The greatest contribution to the formation of severe precipitation was made by Mediterranean–Black Sea cyclones. At the same time, half of all of the cases of extreme precipitation were caused by cyclones generated over the Black Sea only, in all seasons apart from winter. In the mid-troposphere, four types of meridional circulation were identified depending on the location of troughs and ridges, with respect to the Black Sea region. More than 42% of severe precipitation phenomena were accompanied by an isolated high-altitude cyclone in the mid-troposphere over the Black Sea region. The main recommendation that can be drawn from this study is that long-term climatic non-stationarity should be taken into account whenever the risk assessment or hazard analysis is to be carried out. The results can also favor the designing of drainage and sewerage systems in urban areas. The findings of atmospheric patterns can be used for the improvement of extreme precipitation forecasts.

Estimate climatogenic changes in phenorhythms of Olea europaea L. during the growing season in Southern coast of the Crimea carried out. The study used data of olive trees phenological observations and data climatic parameters during 1947–2020. It was established that in the ‘Nikitskaya’ cultivar during studied period of climate change the steady bias tendency to shift to earlier budbreak dates and fruit maturity has been observed since the 80s, the flowering has been since the 90s of the XX century, first leaves separated has been since the beginning of the XXI century and it differs in the highest rates. For the last 2001–2020 the tendency to shift earlier spring phenophases of budbreak and first leaves separated has increased 1.5–2 times. Phenological models using as input variable temperature and photoperiod were developed to predict dates beginning of full flowering ‘Nikitskaya’ olive cultivar. Forecast accuracy amount to 2.7–4.1 days. The expected future change those dates to end of XXI century are also shown.

The study of carbon dioxide gas exchange of leaves of Prunus laurocerasus L., Laurus nobilis L. and Viburnum tinus L. under various environmental conditions was carried out. The greatest resistance to drought and the ability to absorb CO2 under hydrothermal stress was found in Viburnum tinus plants. It was determined that the inhibition of the processes of CO2 absorption with increasing water scarcity begins in the studied species with a decrease in soil moisture to 35% field capacity. Under conditions of soil drought, the amount of CO2 absorbed by Prunus laurocerasus leaves is reduced by 10 times, Laurus nobilis – by 7 times, Viburnum tinus – by 2 times. The positive carbon dioxide gas exchange of Prunus laurocerasus, Laurus nobilis and Viburnum tinus in the hot dry period, when the amount of CO2 absorption exceeds its release during respiration by 1–5.1, 1.5–3.7 and 1.1–6.2 times, respectively, indicates a significant potential these species for optimizing the urban ecosystems of the southern regions of Russia. The developed predictive models allow us to perform a quantitative assessment of the ability of plants to absorb carbon dioxide under various environmental conditions.

On the basis of long-term, high-quality in situ observations on phenological and meteorological data, we parameterised and examined the performances of four single-phase and two two-phase models for the prediction of the leaf unfolding and flowering dates of horse chestnut ( Aesculus hippocastanum L.). Amongst models, those combining the effects of temperature and photoperiod showed the best phenophase prediction, suggesting the influence of photoperiod on the leaf unfolding and flowering of A. hippocastanum . The obtained coefficients showed that the effect of photoperiod was greater on leaf unfolding than on flowering. Comprehensive assessment revealed that the single-phase BCdoy model demonstrated the best fitting for both phenophases. This model also showed sufficiently high accuracy and the transferability of results in time and space. The proposed models can be used to predict the spring phenophases of A. hippocastanum in European and Asian countries, where this ornamental tree species is widely used in urban landscaping, and to optimise control methods against Cameraria ohridella Deschka & Dimić (Lepidoptera, Gracillariidae). For C. ohridella , the first flying out of adults after overwintering begins at the onset of horse chestnut leaf unfolding and mass flight occurs during the full flowering period.

The features of CO2 exchange in leaves of ornamental plants widely used for planting on the Southern coast of Crimea and the Black Sea coast of the Caucasus— Nerium oleander L., Laurus...