Anatomical leaves characteristics of Quercus rubra L. and Quercus robur L. and stand density

The influence of growing of Quercus rubra L. trees in the groups and solitary on leaf indices and their anatomical structure in comparison with indigenous species Quercus robur L. under the same conditions was investigated. The bigger area of leaves and their green weight in plants of both species growing in groups is revealed. Both Q. rubra and Q. robur leaf cuticle thickness is increasing with solitary growth, while in Q. rubra also increasing the height of the cells of the adaxial epidermis; in Q. robur, such changes have not been established. Under conditions of solitary growth of trees, the density of stomata per unit area of the epidermis is greater in both Q. robur and Q. rubra, relative to data from these plants growing in the groups by 30.6% in the first and by 25.3% in the second species. In single trees, there are a decrease in their size. For solitary landing, the length of cells of the palisade mesophyll is greater in the leaves of both tree species, but their width is reduced. The width of the palisade tissue of leaves in Q. rubra is greater in single trees than in groups of plants, while Q. robur has the same pattern, but the difference between the variants is greater (25.89%). Both spongy parenchyma of leaves of Q. rubra growing solitary and growing in groups has not difference in size, but in Q. robur there is some thickening of it by 10.16%. Indicators of the relation of the size of the palisade parenchyma to the spongy parenchyma in both species on the two sites are almost identical. In single trees of both species due to the greater shortage of air and soil moisture, some anatomic-morphological parameters change in the direction of xeromorphism, which can be considered as adaptive.