Comparative characteristics of the climatic conditions of North America and Forest-Steppe and Steppe of Ukraine in connection with the introduction of the North American species of Juglans L. and Populus L. genus

Abstract

Aim. Comparative characteristics of the climatic conditions of North America and Forest-Steppe and Steppe of Ukraine in order to predict the success of the introduction and spreading of the cultural area of the North American species of Juglans L. and Populus L. genus was conducted. Methods. Method of climatic diagrams constructing developed by G. Walter and modified by A. Borhidi in order to reflect and compare characteristic peculiarities of the climate of the natural area concerning introduction was used. Results. It was proved that the area of introduction by precipitation nature had a certain similarity with the climate of North America which caused successful introduction of species of Juglans genus (J.  nigra L., J. cinerea L., J. rupestris Engelm., J. californica Wats., J. major (Torr.) and Populus genus (Р. angulata Sol., Р. candicans Ait., Р.  deltoides Marsh., Р. balsamifera L., Р. trichocarpa) based on the analysis of climatic diagrams with climatic indicators of natural distribution areas of the species of Juglans and Populus. genus in North America (Las Vegas, San Diego, Pasadena, New York, San Francisco, Salt Lake City, Chicago) and the area of introduction – Forest-Steppe and Steppe of Ukraine (Kyiv, Uman, Vinnytsia, Kherson). Average temperature of absolute minimum ones was one of the limiting factors, on which the success of winter hibernation depended, and consequently – introduction. Conclusions. Therefore, the area of introduction had some similarity with the area of the eastern part of the USA according to that indicator. There is a significant difference between the studied areas by such indicator as the average annual rainfall. The amount of precipitation in Ukraine is almost 1.5-2 times lower than in the USA. The difference between the indicators of rainfall and evaporation per year was compared while analyzing water balance of the territory. This balance in North America as in Ukraine is almost zero or displaced towards the humidity remains that has a beneficial effect on plants. Plants of the species of Juglans and Populus genus successfully adapted to the soil-and-climatic conditions ofUkraine, plentifully bloom and bear fruit every year, and some of them even form a self-seedling, which indicates their successful acclimatization due to the high plasticity.