The flora of the Batumi landfill (Adjara, Georgia)

. Results of floristic research conducted within the territory of the Batumi landfill (Adjara, Georgia) are presented. The total area of the site is about 20 hectares, of which 10 hectares are active and the remaining part was closed in the beginning of the 21 st century. In the closed area, the processes of formation of stabilized plant communities and spontaneous vegetation successions are going on. As a result of the survey, we revealed 244 species of vascular plants belonging to 163 genera of 59 families. Among them, 86 species are considered native and 158 species are alien. Among the listed species, 94 are representatives of the ruderal flora and others are species characteristic for various other habitats. сукцесійні процеси в рослинному Внаслідок 244 види рослин, що 59 Серед них видів вважаються аборигенними, 158 видів чужорідними. наведених


Introduction
There are no present-day local floras in the world that have not been exposed to at least some, direct or indirect, anthropogenic impact. The anthropogenic transformation of vegetation covers all territories where human activities are manifested even to a minimal extent. As a result of the global anthropogenic impact, technogenic ecotopes are formed; those ecotopes have no natural analogues and they are often results of urbanization and include urban landscapes inhabited by species of the urban flora, ruderal flora, etc.
The urbanization index in Georgia is currently 53%. Among the cities and towns of Georgia, the city of Batumi is characterized by the fast urban growth and development.
In the middle of the 20 th century the population of Batumi, according to the official data, was only slightly more than 82 thousand inhabitants. However, at the beginning of the 21 st century it reached 120 thousand, and by 2018 the current estimate is ca. 163 thousand people or, according to unofficial data, even more. With the increase of its population, the city area was growing as well.
From the beginning of the 21 st century, various construction activities, settlement and urban development of new territories continued in the Adjara seaside, accompanied by establishment, reconstruction and/or development of parks, gardens, and recreational places. For construction of residential buildings, shore protection works, other infrastructural and development projects, the construction materials are usually transported from one to another district of the city; the materials and goods are also imported from foreign countries. Most of ornamental plants (including their seeds and other planting material) are imported from abroad, which often results in unintentional introduction of alien weedy species, many of which are potential invaders. All of this adds to import of plants by the horticulturalists and plant lovers or the entrepreneurs for ornamental or production purposes; those plants spread in natural, disturbed, and artificial habitats, such as abandoned construction areas, roadsides, streams and canals, and so on.
The city of Batumi and its adjacent areas play an important role in the processes of immigration and spread of alien plants in the region. The city is an open gateway between the eastern and western countries. It is a trade and transportation hub between Europe and Asia, from where different goods are carried in and through Georgia. The famous Batumi Botanical Garden, established in the 1880s and officially opened in 1912, is the major horticultural and plant research center of the Caucasus; it also played and continues to play an exceptionally important role in both deliberate and unintentional plant introduction, acclimation and naturalization in the region.
Other areas contributing to the alien plants diversity in the Batumi area is the Batumi Boulevard stretching along the Black Sea shore; it is a green area with the centurylong history and rich introduced flora; together with other parks and green areas it also contributes to immigration and alien plants.
All those factors mentioned above promote intentional or unintentional spread of alien plants in the city territory and beyond. Many of those plants eventually find their way to the Batumi landfill territory with its peculiar transformed plant communities. In this area alien species often survive, proliferate, and form stable populations, in turn enriching the surrounding areas with unwanted aliens. Thus, our objective for the present research was to study the vegetation in the inactive, closed landfill area and its adjacent territory.

Materials and methods
The study site is located in the southwestern part of Georgia, in the floristic region of Adjara, 10-12 km from Batumi, on the right bank of the Chorokhi River, mainly at elevations of 1-5 m above sea level, between 41° 36.022´N and 41° 35.298´E. The total area of the Batumi landfill is about 20 hectares, of which 10 hectares are occupied by the actively used area, while other areas are now closed for waste dumping; that results in ongoing processes of formation of stabilized plant communities (Fig. 1, 2).
The landfill has been operating since the last century (officially established in the study site in 1965). Initially, the waste was only from the territory of Batumi, but during recent years other municipalities of Adjara have been added as customers of the landfill services. Almost all types of waste are found in this area, including household, construction, industrial waste, etc.
The climate of the study area is characterized by specific features and spatial variability. Seaside Adjara in general has a humid subtropical climate. During most of the year, western humid winds are dominant and only in winter months inland winds occurrences increase. The average annual temperature is +13°-15° C, while the coldest month's average temperature being +5.9-7.5 °C. Absolute temperatures rarely drop below -8°. In the warmest months (July-August), the average temperature is +22-23 °C, the highest temperature reaching +39-40 °C. The average air humidity is 80-87% (Javakhishvili, 1926;Kordzakhia, 1961;Maruashvili, 1964;Nijaradze, 1978).
Investigation of the landfill flora was conducted during the period of 2015-2018. The main research method was the traditional route survey, which included plant description, photography, plant sampling, and laboratory processing, identification and herbarium preparation and curation. Laboratory activities were conducted in the Shota Rustaveli State University of Batumi, the Institute of Phytopathology and Biodiversity in Kobuleti.
The time of the initial collection (first records) of nonnative plants in the Adjara floristic district was determined following the herbarium specimens deposited in the Batumi Botanical Garden (BATU) and from various publications (Davitadze, 2001(Davitadze, , 2002Kikodze et al., 2010;Mikeladze, 2013Mikeladze, , 2017Sharabidze et al., 2018).

Results and discussion
After identification of the plant samples collected in the Batumi landfill, we registered totally 244 species of vascular plants that represent 59 families and 163 genera (  Of the species registered in the Batumi landfill, 86 species (35.25%) are considered native and 158 species (64.75%) are aliens (introduced). Among aliens, 48 species are of East Asian origin, 34 species originated in Europe, 1 species is Australian, 13 -South American, 29 -North American, and 33 are Mediterranean ones (Fig. 3).
Our phytogeographical analysis demonstrated the largest number of East Asian species, which is due to many factors. In particular, those factors include similar climatic conditions (including high humidity, precipitation, favorable temperatures during the whole year, fertile soils, etc.). Also, it reflects the history of introduction of taxa for cultivation, as well as their associated weeds. For example, it is known that East Asia was considered among highest geographical priorities for introduction of plants in the Batumi Botanical Garden since its establishment. The species of the Mediterranean and European origin follow by their number, which is also partly determined by the phytogeographic structure of the Adjara flora.
The analysis of life forms of the Batumi landfill flora demonstrated the predominance of therophytes and hemicryptophytes. Therophytes (herbaceous annuals) are represented by 108 (44.26%) species. The second place is occupied by hemicryptophytes with 60 species (26.10%) of mainly biennial and perennial herbaceous plants ( Table 2).
The dominant positions of therophytes and hemicryptophytes are related to the peculiarities of the species composition of the local ruderal flora. Phanerophytes are quite diverse, out of 33 species 14 are local and 19 are of alien origin.
In the study area, phanerophytes usually flower, bear fruit, establish seedlings normally, and thus they are characterized by a complete cycle of development; sometimes they dominate in local plant communities.
Besides the typical ruderal species recorded in the Batumi landfill (inactive or closed area) we came across the species characteristic for various habitats, such asforests, moist meadows, low and high mountain zones, etc. Out of 244 species, 94 are representatives of the ruderal flora (Tabl. E1).
Furthermore, a number of sub-spontaneously distributed cultivated species (occasional escapes, such as maize, beans, tomato, pumpkin, watermelon, melon and other crop plants) were also found. Usually such garden escapes or agricultural crops are only of ephemeral occurrence, not forming stable populations.

Conclusions
Among 244   conditions of Adjara and many East Asian regions (including high humidity and precipitation, favorable temperatures during the whole year, fertile soils, etc.). We understand that the list of species reliably registered to date in the Batumi landfill area is not complete and additional species (both alien and native ones) will be registered there in the future. Because of that we are planning to continue our surveys of the landfill flora, especially for monitoring invasive and potentially invasive species. The species list presented here will serve as a reference checklist reflecting the present state of our knowledge of the local flora; it will be amended and improved during the future research.