Analysis of changes in plant composition on fallowed lands of different age at the Nadezhdinskaya drainage system (Jewish Autonomous Region)

The article expounds the results of the plant successions on the age-related fallowed lands located in boarders of the same drainage system. The goal of the study is to assess plant shifts on fallowed lands of the Nadezhdinskaya drainage system which is in the Jewish Autonomous region. During the study, it was determined that a grassy cover belonging to the wormwood-cereal- motley grass association forms appear on the fallowed land after 5 years after the date of agricultural use termination. With the prolongation of the fallow land age period, it is observed the land overgrowth with woody and shrubby vegetation, with the decline of the weedy-ruderal vegetation proportion. The pioneer species of trees on the fallowed land belong to the Salicaceae family. They grow separately on the young and middle-aged fallowed land. The formation of separate groupings of the genus Salix is noted on the land abandoned for more than 25 years. A comparative analysis of the vascular plant species richness in age-related deposits shows the difference in the number of represented species. Middle-aged fallowed land (15 years) has the highest number of species - 35, and the least rich in species diversity fallow land of 6-10 years accounts only 13 species. All deposits are dominated by the Asteraceae family, but with the deposit increasing age, it is observed increasing of other families like Rosaceae, Poaceae and Fabaceae. It is also found that perennial and annual weed-ruderal plants - Elsholtzia ciliata (Thunb.) Hyl, Bidenes radiata Thuill. Artemisia argyi H. Lev. & Vaniot, Artemisia vulgaris L. Geum aleppicum Jacq. - predominate in young deposits. In middle-aged and old deposits, the genus Artemisia abundance decreases to 10%. Besides, this geobotanical analysis has made it possible to identify the fallowed lands overgrowth stages: weedy - rhizomatous - woody shrubby. The research shows that the the fallowed lands successions depend on a lot of factors including soil types, humidity, general climate conditions and anthropogenic impact.