Water regime and dust retention capacity of silver birch Betula pendula Roth. in Northern Kazakhstan

The purpose of the research was to determine the water regime and identify the nature of dust retention capacity of assimilation apparatus in artificial birch stands in green zone of Nur-Sultan (Northern Kazakhstan). The objects of the research were 16-year-old Betula pendula Roth. forest crops, some of which were transplanted at the age of 8 into the interrow space. Some water regime features of forest crops were considered to determine their adaptive ability to soil and climatic conditions. The intensity of leaf transpiration, relative water content in leaves, and water deficiency were studied. When making observations, it was found that there was no reliable difference between the water regime indicators in the sample areas in transplanted and non-transplanted crops. So, the results of the research are presented without taking into account peculiarities of the sample area location. A high water-holding capacity of the plant leaves was revealed, it amounted 96.98 %. The average transpiration rate during the growing season was 176 mg/g ∙ h, with the highest average transpiration rate (229 mg/g ∙ h) detected in July, and the lowest in August (162 mg/g ∙ h). The data obtained showed weak intensity of moisture evaporation by leaves. This indicates a low water deficit of the plants, which was 8.96 % after leaf was fully saturated with moisture. Ratio of retained dust and leaf area of silver birch showed that 1 cm2 of assimilation apparatus accumulated on average 0.1 mg of particulate matter. The amount of dust revealed that at a high location, more particulate matter is accumulated per unit area of assimilation apparatus than at a low location. The largest amount of dust (0.117 mg cm2) was deposited at a distance of 1000 meters from the highway, and the smallest amount (0.091 mg/cm2) - at a distance of 200 meters. Topographic features and presence of protective birch strip influenced this fact. The research revealed that a large leaf area is not a guarantee of high dust retention capacity.