Fruiting specifics of drooping birch in the Krasnoyarsk forest-steppe

Abstract

Morphometric quantitative (length and width of female catkins, length and width of birch-capsules) and functional parameters (germination and germination power of birch-capsules, length of shoots) of the female reproductive sphere of drooping birch Betula pendula Roth. trees growing in the zone of technogenic emissions’ impact in the city of Krasnoyarsk have been studied. The studies were carried out on permanent sample plots established in birch stands growing in the southeastern, northern and northeastern environments of the city of Krasnoyarsk. Reproductive processes of drooping birch in the Krasnoyarsk forest-steppe were studied for the first time. The studies have shown that two-year periodicity of fruiting is characteristic of drooping birch trees of the Krasnoyarsk forest-steppe. The sizes of female catkins and birch-capsules vary depending on the genotypic characteristics of trees, the conditions of growth of the tree stand, also in different years of studies. With an increase in the degree of technogenic load, birch trees showed certain signs of a decrease in reproductive activity (a decrease in the morphometric parameters of female catkins and birch-capsules), as well as qualitative indicators (germination and germination power) of birch-capsules. It was revealed that the length of female catkins and the width of birch-capsules are negatively correlated with the content of fluorine in the foliage. The regression equations were calculated within the range of parameters: y = –0.0489x + 2.8127 и y = –0.0346x + 1.7732. The quality characteristics of birch-capsules (germination and germination power) were negatively correlated with the amount of settled dust on the lamines, as well as with the fluorine content in the leaf mass. At the same time, the maximum quality indicators were characterized by fruits harvested in background conditions. Functional signs of the female reproductive sphere of drooping birch are the diagnostic criteria for assessing the condition of trees, and can also be a direct indicator of the environmental conditions of growth.

Keywords

• mixed herbaceous birch stands
• female reproductive structures
• catkins
• birch-capsules
• technogenic dust
• gross fluorine