Biodiversity of young trees in the birch forests in the Republic of Mari El

In article results of studying of a biodiversity of young trees of the birch forest are given in the Republic of Mari El. The age of forest stands was 60-65 years. During work studied floristic structure, occurrence assessment was carried out, determined the average height and diameter of young trees. Made their recalculation for definition of characteristics of young trees, on platforms on 4 m2 two cross tape transects of 1 m of width. Analysis of the results showed that all of the undergrowth consists of a population of 10 species of woody plants: Acer platanoides L., Tilia cordata Mill., Picea x fennica Regel Kom., Quercus robur L., Ulmus glabra Huds., Populus tremula L., Betula pubescens Ehrh., Betula pendula Roth., Abies sibirica Leb., Pinus silvestris L.. Under the canopy of the forest is the most intense renewal of shade-tolerant broadleaf species - Acer platanoides, Tilia cordata, Ulmus glabra. Light-loving species - Betula pendula and Pinus silvestris - found only in the “windows”. According to the density of undergrowth on all plots refers to the “rare” category. Stem diameter and height of the plants that make up the undergrowth depend on the type of plant and from phytocenosis in which they grow. The diameter of the stem regrowth in different species varies from 0.6 to 6.8 in aspen see Finnish spruce. Plant height ranged from 0.6 m to 4.6 m. The height and diameter are correlated with the occurrence. The diameter of the trunk in different species of undergrowth varies from 0.6 in Populus tremula to 6.8 cm in Picea x fennica. Plant height ranged from 0.6 m to 4.6 m. The height and diameter are correlated with the occurrence. In most cases, the undergrowth in the studied sample areas is classified as “large”.