Population structure of Betula pendula (Betulaceae) on iron ore mine dumps (tailings) of the Kryvyi Rih area

The article presents the results of investigation of the population structure of Betula pendula at four iron ore mine dumps (tailings) of the Kryvyi Rih area, of the Northern and Central Mining-and-Processing combines (NorthMPC and CMPC). Totally, eleven population loci on the Petrivskyi and Avtomobilnyi dumps of the Pershotravnevyi quarry, dump No. 7 and Petrivskyi-2 dump of the Hleyuvatskyi quarry of CMPC were investigated. The area of population loci, number and density of different aged individuals in each locus, as well as their percentage for each dump were ascertained. The morphometric parameters of the largest trees of Betula pendula on the Petrivskyi dump and trees of the generative age in all population loci were studied. A high-level vitality state of adult (mature) individuals in all population loci has been noted. We observed frequent changes of life forms of Betula pendula: sprout-forming, trees with few trunks (up to 3) and multi-stemmed trees (more than 3 trunks) formed as a result of the development of additional trunks from resting or adventitious buds under specific conditions of iron ore dumps in the Kryvyi Rih area. One-sided, bilateral and versatile dominant directions of the spread of self-seedlings in various loci were revealed. An analysis of the age structure demonstrated that out of eleven population loci, ten are young, in six of them plants are capable of complete self-renewal; a single locus is ripening, in which only 58% of generative individuals can recover. According to results of the study of the vitality structure, eight population loci belong to the flourishing type and three – to the depressive one. It has been found that the vitality of individuals depends on the environmental conditions as well as physical and chemical properties of the substrate. Due to constant self-renewal and self-maintenance in all the eleven population loci, Betula pendula can form stable primary populations under extreme conditions and thus is perspective for recultivation of technogenically disturbed landscapes.