Aridization of the climate in the Western Caspian region as a factor in reducing the productivity of pasture phytocenoses

Background. The semi-desert zone of the Western Caspian Sea is subject to severe climatic changes during the growing season of crops, including on natural pasture lands, which causes desertification of territories. The object of consideration of the arid territory of the Western Caspian Sea for climate aridization is the Neftekumsky district, where the factors of abnormal climatic changes characteristic of this zone are most pronounced, affecting, among other things, the productivity of pasture phytocenoses. The purpose to study the dynamics of changes in climatic conditions in the Western Caspian region with an assessment of the decrease in productivity of pasture phytocenoses. Results. The results of the analysis of climate change for April - October of the 31-year research period (1993-2023) showed an average annual temperature increase of 0.05 °C with its most intense rate from 2018 to 2023, amounting to 0.11 °C. A similar trend is observed in terms of precipitation, the annual decrease from 2018 to 2023 is 11.8 mm. There is an intensive decrease in the value of the HTC in the period from April to October 2011-2023 at a rate of 0.03 units per year, which indicates an intensive aridization of the climate. Analysis of the data from the register of droughts showed that if in the first decade (1993-2002) periods of severe droughts were observed in 34.3% of cases, then in the last decade (2014-2023) – in 47.1%, therefore, an intensive process of aridization is observed. Conclusion. An analysis of the data of droughts of the 31-year period by month (April – October) showed that the most severe drought is observed in July (51.6% of years) and August (54.8% of years). If in August 1993-2002 severe droughts were observed in 5 cases of certain years, then in the period 2014-2023 there were 9 units. Significant fluctuations in pasture productivity have been established in the years of research that differ in agro–climatic conditions (2018-2023). In a favorable year 2021, with a value of 0.64 HTC in April and May, and 1.86 in June, the productivity of wormwood and cereal pasture feed was 1.18 t/ha, in a critically abnormal 2022 with an even 0.2 – 0.25 HTC of April - May, only 0.53 t/ha. A similar pattern was established for ephemeral-cereal and mixed-grass pastures, where productivity decreased by 0.52 and 0.53 t/ha, respectively, compared with 2021.