FEATURES OF CHANGES IN SIGNS DURING THE SEASONAL DEVELOPMENT OF THE LEAVES OF THE HANGING BIRCH (<i>BETULA PENDULA</i> ROTH)
The paper presents the results of studying the variability of the leaves of the hanging birch ( Betula pendula Roth), which were carried out during the growing season of 2018 on permanent test areas in the pollution zone and in the residential area of the Ufa industrial Center. 10 trees were identified and numbered on the trial areas. The relative vital condition of the studied trees is characterized as "healthy". From each tree in the summer-autumn period (June, July, August, September, October), 10 leaves were selected from brachiblasts. For each sheet, 5 parameters were measured on the left and right half and an integral indicator of fluctuating asymmetry was calculated. When comparing the features of the seasonal development of birch leaves in the industrial and residential zones, morphological differences were established. According to Fischer's criterion, during the growing season, the 2nd feature was the most informative (the length of the second vein of the second order from the base of the leaf). In July, the greatest variability of leaves was revealed by a set of signs (2, 3, 4, 5). It should be noted that the 1st feature (the width of the leaf halves) weakly reflects deviations in the formation of asymmetry of birch leaves. The data obtained indicate the uneven seasonal development of birch leaves in the Ufa industrial Center against the background of the temperature regime during 2017-2018.