Dynamics of the segetal species composition in the Sverdlovsk Region.
Over the last 150 years, the changes of segetal plant species composition in the Central Urals were traced. Two species checklists were used in a comparative analysis. A historical checklist of segetal plant species for the period from 1870 to 1930 was compiled on the base of published data and herbarium specimens, and a modern checklist of segetal plant species resulted from the authors' investigations during 1997-2016. The results has shown that, firstly, the historical and modern segetal flora are presented by almost equal species number, 235 and 256 respectively. Secondly, they consist of nearly equivalent groups: about 60% are aboriginal species, and 40% are alien species. Both the historical and modern segetal floras have high similarity between aboriginal and alien species groups. The most part of aboriginal species as well as alien species remain in the weed species composition in the Central Urals despite crucial changes in farming systems. The historical and modern segetal floras differ by small groups: about 40 aboriginal and 25 alien species have vanished from the weed species checklist, and about as many (46 aboriginal and 40 alien species) have appeared in the modern segetal flora. The aboriginal and alien species for which the changes in their occurrence were marked are listed.