The structure and dynamics of vegetation on the different age abandoned fields

The aim of this research was to study the structure and dynamics of vegetation cover on abandoned fields of different age. The studies were conducted from 2006 to 2015 on the territory of Novousmansky region on abandoned fields, which were formed in 1990 and 1998 years. The objects under study were different in types of soils, moisture conditions and nature of vegetation. To establish changes taking place in the structure of the vegetation cover, floristic composition, abundance of ecology-coenotic groups and life forms of plants were determined. The results of the investigation have shown that the representatives of the families Asteraceae and Rosacea prevail in the number of species.In the result of analysis the ecology-coenotic composition it was found that the most numerous and stable is a group of plants of wet meadows, and there is a tendency to increase the number of steppe species. A quarter of all species on abandoned fields belonged to the forest flora. Relatively stable group was formed by adventitious species, especially Acer negundo L. The half area was occupied by wet meadow species, about 20% - by forest plants. During the years of research on some abandoned fields increased area occupied by steppe species, on others - an area of forest flora, mainly due to the population of Acer negundo. On investigated abandoned fields the rhizomatous plants were dominated, they occupied nearly the half of the area. The stable was a group of turf grasses, for 10 years they practically did not change its stake in vegetation structure. On older (26 years) abandoned fields it was found a tendency to the formation of meadow-steppe vegetation, which was formed by perennial grasses. More young (18-year) abandoned fields actively overgrown by trees. Thus, planning the development of abandoned fields should take attention the character of the surrounding vegetation. The optimal solution would be the introduction of the agricultural use all the abandoned fields area, and not its separate parts. It's connect with the influence of advent species which invasion activity is strongly increase in local violations of vegetation.