Dynamics of phytomass of ground vegetation cover plants in post-harvest origin deciduous forests of the middle taiga

The results of evaluation of the dynamics of phytomass of plants ground vegetation cover in deciduous phytocenoses of post-harvest origin for a 10-year period in the middle taiga of the Komi Republic are presented. The research was conducted in the young birch-spruce forest and aspen-birch forest bilberry-herbs type, formed on a place of cutting down the spruce bilberry and bilberry -polytric type. Geobotanical and taxation characteristics of deciduous forests are given in the course of research. The total number of plant species growing in the studied phytocenoses is 44, including 34 plants species of ground vegetation cover, with a total projective cover of 60 to 100%. The phytomass of ground vegetation cover of the studied phytocenoses, for a 10-year period increases: in birch-spruce forest in 1.3, in aspen-birch forest -1.5 times. The largest amount of phytomass is accumulated in the ground vegetation cover of birch-spruce forest. The phytomass of the ground cover is dominated by herbs and mosses. In the aspen-birch forest in 2005 on herbs had more than 40%, shrubs - 20%, moss - about 40% of the total weight of the plant ground cover. Over a 10-year period, the ratio of these groups of plants has changed in the direction of increasing the mass of mosses. In birch-spruce forest in 2015, compared with 2005, the share of herbs in the total phytomass decreased to 20%, and mosses increased by almost 10%, shrubs - almost unchanged. In both type of forest phytomass of ferns, horsetails and planes on average does not exceed 5%, cereals - less than 10% of the total phytomass of plants. The ratio of grass phytomass to the mass of mosses during the study period varies from 1:2 to 1:3 in the birch-spruce and from 1:1 to 1:2 in the aspen-birch phytocenosis. A positive correlation (r=0.6÷0.7) was found between the total projective cover and phytomass of ground vegetation cover, which indicates a certain influence of the spatial distribution of plants in the studied phytocenoses on their mass. The estimation of phytomass variability within the studied phytocenoses using the coefficient of variation (CV) showed a relatively uniform distribution of moss and shrub phytomass in birch-spruce forest in 2005 and an increase in their variability in 10 years, in aspen-birch forest, a decrease.