Alien species in the flora of vascular plants of the Omsk region: general data

The first results of the research of invasive and potentially invasive species of vascular plants flora of the Omsk region have been presented. The list of invasive and potentially invasive species is based on the data of the preliminary analysis of the literature sources of the XIX-XXI centuries, herbarium collections and private library of the author. As a result were received the data for the probable time of the appearance, extent of naturalizing and distribution of 90 species in the region. Four quarantine plant species are registered on the territory of the region: Solanum triflorum, Acroptilon repens, Cuscuta monogyna and C. campestris. In recent years there has been a tendency of the increase of the infested area by Acroptilon repens and Solanum triflorum. On the territory of Omsk region there are 3 “transformer” species (the 1st category): Acer negundo, Elodea canadensis and Hordeum jubatum. There are 13 species belonging to the 2nd category dispersed and naturalized. The most numerous are the species of the 3th category (adventive species that are settling and naturalizing in disturbed habitats) and that includes 43 species, the 4th includes 31 species. According to the degree of naturalization the less studied and the less numerous group N0-N2 includes only 1 species Impatiens balsamina. The most numerous group with the degree of N3-N6 unites more than 57 species, there are 16 species in the group N7-N9. The Omsk region has a well-developed system of roads and railways due to the geographical location and economic development, that’s why the region is open to invasion by allochthonous species, arriving especially from the West and South. In the Southern districts of the region the invasive potential is higher than in the Northern ones, due to the agricultural development (a large number of disturbed habitats which are open for invasion).