Adventitious plants of the flora of the city of Omsk

The data of the study and analysis of the adventiv element of the flora of the city of Omsk are presented. The up dated list of adventitious plants of the flora of the city of Omsk is given. T he invasive plants listed in the Black Book of Siberia are indicated. Synanthropization is a characteristic feature of th e modern development of the vegetation cover of anthropogenically transformed territories. It allows adventitious (introduced) species to penetrate into the local flora. Many adv entitious plants, spreading both with the conscious and unconscious participation of a person , are capable of naturalization, becoming permanent components of the vegetation cov er of urbanized territories. The study of the process of replenishing the flora with adven titious plants is one of the elements of biomonitoring of the state of the environment. Omsk, being one of the oldest cities in Western Sib eria, currently includes 5 administrative districts with different ages and di fferent degrees of urbanization, and is a combination of man-made and biogenic landscapes. Th e city continues to grow in three directions along the banks of the Om and Irtysh riv ers. The last decade has been marked by an increase in the density of its development and t he degree of improvement, while in the modern layout of residential quarters, a significan t part of the area is allocated for landscaping. The modern area of the city is more th an 572 km. The branch of the West Siberian Railway, the developed river shipping comp any, and air communication made Omsk a major transport and distribution center. The surroundings of the regional center have almost no natural forests. Forest vegetation, concentrated mainly on the urban outski rts, is mainly secondary, the dominant among woody plants are Betula pendula, Populus trem ula. The remains of a natural pine forest are located on the right-bank part of the ci ty. Areas of natural meadow and steppe vegetation are preserved in urban recreational area s. Willow-poplar and shrub communities are characteristic of the floodplain and islands al ong the river banks. Saline habitats in the urban area determine the presence of cenoses of hal ophytes [1]. The main floristic studies of adventitious plants o f the flora of the city of Omsk were conducted in the period from 2000 to 2003, followed by monitoring in 2018-2020 by the traditional route method, allowed to register 147 a dventitious species, which amounted to 21.3 % of the total flora of the city of Omsk. The novelties of monitoring studies in 2018* Corresponding author: antipm@list.ru © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). BIO Web of Conferences 38, 00004 (2021) Northern Asia Plant Diversity 2021 https://doi.org/10.1051/bioconf/20213800004

The analysis of the ecological spectrum showed that adventitious species have the opportunity to develop a variety of biotopes in the study area and are represented by various ecological groups. A significant percentage of mesophytes (more than 50 %) indicates the prevalence of substrates with moderate moisture. At the same time, the alien xerophytes and mesoxerophytes, which together contain almost 1/3 of the total composition of advents, confirm the trend of xerophitization of urbanized territories. In addition, 13 species were identified that can grow in populated habitats (halophytes). When analyzing the biomorphs of the studied plants according to the classification of K. Raunkier, it turned out that most of them are herbaceous plants with a short life cycle (annual plants), which is a indication of a long and intensive anthropogenic influence on the vegetation cover of the studied territory. The geographical analysis of the advent element, carried out by types of habitats and indicating the main ways of plant migration to the studied territory, revealed that the flora of the city of Omsk is actively replenished due to species whose range covers the territories of Europe and Asia, and the northern hemisphere as a whole. The location of the regional center and the developed transport network contributes to the links with the flora of Central Asia, Kazakhstan, and Central Asia. Thanks to the species that escaped their natural habitat, the European group itself is enriched and the American group appears. In general, synanthropization helps to strengthen the positions of broad-area species in the flora. Traditionally, when analyzing adventitious plants, they are distinguished by the time of introduction, the method of introduction, as well as the degree of naturalization [2].
In the course of the analysis of the advent component of the flora of Omsk, classifications based on two criteria were used -the method of introduction and the degree of naturalization, which allow to identify the role of a person in the process of transferring advent trees to new territories, and the level of their adaptation to new geographical conditions.
To identify the method of introduction, classification groups that were applied for the study of the adventitious flora of the Voronezh region: xenophytes -immigrants who spontaneously appeared on the studied territory as a result of transcontinental, transzonal and interzonal transfer due to human activity; ergaziolipophytes -introduced species, planted in natural conditions or on natural-anthropogenic habitats and growing there without human care; ergaziophygophytes -introduced species, leaving the places of culture [2,3].
To determine the degree of naturalization, a more compact version of the classification of the authors of the adventive flora of the Voronezh region was used: ephemerophytesfluctuating species that appear and disappear in local habitats, colonophytes-species that are firmly entrenched in new habitats, but do not spread from them, epecophytes -alien species that settle in disturbed habitats (species of ruderal communities). At the same time, the proposed group of agriophytes was not distinguished by us, since the natural vegetation cover on the territory we studied was practically not preserved. According to the method of introduction, xenophytes are leading -79% of the total number of advents, which is due to various options of transport communication of the city of Omsk with various regions of the country, as well as Kazakhstan. Ergaziolipophytes are represented by woody plants that have been successfully introduced, are actively used in landscaping, give good self-seeding and do not require attention. The group of ergasiophygophytes was formed mainly by herbaceous unpretentious plants grown as food and ornamental, capable of easily leaving the culture.
The analysis of adventitious plants of the flora of the city of Omsk by the degree of naturalization revealed a significant percentage of alien species that are quite successfully mastered and fixed in the new territory, and make up groups of colonophytes and epecophytes. The resulting total result of 89 % indicates the successful naturalization of most of the advent, which emphasizes the anthropogenic transformation of the flora of the city of Omsk. List