THE CLIMATIC FLUCTUATIONS IN DRY STEPPES AND THEIR ROLE IN THE PROCESS OF REGENERATION
Pugacheva A.M. The Climatic Fluctuations in Dry Steppes and Their Role in the Process of Regeneration // Arid ecosystems. 2020. V. 26. № 3 (84). P. 14-22. | PDF
For the first time a research paper presents the results of the analyses of moisture-providing during the active growing seasons in dry steppes. The climatic fluctuations were examined together with the defining their characteristics. Contrary to the common opinion, that the steppe zone receives the highest rainfall in summer and that fact becomes its special feature including subzones, the analyses of 64 years show that the dry steppes of Lower Volga region received the highest rainfall in summer only in 39 % of years, in spring – in 27% of years and in autumn – in 34% of years. The time-series analysis during the seasons of moisture-providing for more than 50 years identified the general trend of decrease in summer rainfall and the increase of spring and autumn rainfall. The processing of time-series by exponential smoothing and the regression analysis points to the rate of humidity increase in spring after the critical years of 1990 and 1991, which is proved by Student’s t-test (probability 0,00005) together with the humidity decrease in autumn (probability 0,01). These features characterize the regeneration processes of secondary phytocenoses on fallow lands in the form of domination of loose bunch cereaks and dense cereals in them because the moisture-providing in late spring (May) and early summer (June) has the primary importance for their development. In addition, the characteristics of moisture-providing show a tendency towards aridization. The number of species of Poaceae family in the examined phytocenoses is 28 with 24.5% of representation. Moreover, this fact characterizes the existence of ephemeral plants and ephemeroids in the plant community, because their vital activity mainly depends on the spring rainfall. The number of their species is 8% of the total.
Keywords: climatic fluctuations, dry steppes, regeneration, plant communities, phytocenoses, exponential smoothing, regression analysis.
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