Postagrogenic Transformation and Assessment of Carbon Stocks of Karelia Unused Forage Lands' Phytocenosis

On forage lands overgrown with vegetation of low value for agricultural production, the postagrogenic transformation of the grass cover manifested itself in a decrease in the total projective coverage up to 1.7 times (compared with hayfields 94.8–99.0%) and heterogeneity of the species composition. The coefficients of floral similarity of haymaking Jacquard and forage lands with the curtin type of overgrowth averaged 0.45, and with the solid type – 0.39. Grass-cereal or cereal-grass stands were mainly composed of rhizomatous and turf-bearing plant species. The reserves of absolutely dry aboveground mass (4.86 t/ha) and carbon (2.04 t C/ha) of hayfields significantly exceeded (up to 1.5 times) the corresponding indicators of unused forage lands.