Floristic characteristics of some synanthropic plant communities of the Kobuleti lowland (Adjara, Georgia)

The materials of the field research of synanthropic vegetation in the territory of the Kobuleti in the 2016– 2020 years are provided. In particular, 134 taxa belonging to 49 families and 97 genera were revealed in the three different plant communities ( Cryptomerietum japonicae, Eucalyptetum-viminali-globulo-cinerei, and Cinnamomo glanduliferae-Cryptomerietum japonicae ) in the Kobuleti lowland. The community Cryptomerietum japonicae comprises 66 taxa, 33 of which are native, and 33 have an alien origin. Woody plants in Cryptomerietum japonicae are represented by 15 taxa. The community Eucalyptetum-viminali-globulo-cinerei comprises 91 taxa, 36 of which are native and 55 are alien. Woody plants in Eucalyptetum-viminali-globulo-cinerei are represented with 17 taxa, while the rest 74 taxa are herbaceous. In Cinnamomo glanduliferae-Cryptomerietum japonicae there are discovered 49 plant taxa, including 25 native and 24 aliens. In this community, 16 taxa are represented by woody plants and 33 taxa – by herbaceous ones. Therefore, in the investigated region, 60 taxa (44.77 %) were found to be native and 74 taxa (55.23 %) alien. Among aliens, 31 taxa have East Asian origin, 16 taxa are from the Mediterranean, 13 taxa originated from Europe, ten taxa originated from North American, and four – originated from Australia. Despite cuttings and artificial planting of alien representatives, some indigenous woody species (i.e., Corylus avellana, Frangula alnus, Vaccinium arctostaphylos, Smilax excelsa, Quercus hartwissiana, Carpinus caucasica, Castanea sativa, and Hedera colchica ) still occur in this territory. Both native and alien taxa participate in the formation of the described landscape structure. Successional events have started in the Kolkheti Lowland in ancient times. It is a long-term process, which is still ongoing, as our observations confirmed it. results all


Introduction
The transformation of the flora and vegetation is one of the significant challenges in the modern world related to human activity. The human disruption impact on the ecosystems promotes their response through the secondary autogenic succession. Such successions vary depending on specific anthropogenic influence on ecosystem and allow plant species with foreign origin invade and inhabit local plant communities (Kornaś, 1990;Richardson & Pyšek, 2006;Fudali, 2009;Opálková & Cimalová, 2012;Solomakha et al., 2012;Ziaja & Wójcik, 2015;Mikeladze, 2015;Kostryukova et al., 2017).
The influence of anthropogenic factors, irrational use of natural sources, and careless and abandoned agricultural lands have led to a remarkable transformation of flora and vegetation. Such transformation is reflected in the invasion of alien plant species in the disturbed habitats and syngeneic succession. This is a result of anthropogenic-induced invasion processes in the florogenesis that oppressed indigenous species, in particular, those 'shelters' (refugia) of which were destroyed (Ginkul, 1936;Mazurenko & Khokhriakov, 1972;Davitadze, 1980Davitadze, , 2001Davitadze, , 2002Richardson et al., 2000;Richardson & Pyšek, 2006;Simberloff, 2013).
Active phytoinvasion is also an actual problem for the South Kolkhis (Adjara). Investigation of the transformed vegetation in the coastal Adjara lowland and foothills considered the principal targets for phytoinvasion in Kolkhis is highly relevant. To predict and monitor local vegetation transformations, it is essential to survey exiting plant communities in terms of restorative succession (consistent) change.

Material and methods
The research was carried in 2016-2020 in the Kobuleti lowland. The study territory is located in Georgia, in the floristic region of the Western Georgia-Kolkheti Lowland (Fig. 1). The object within the phytogeographical division belongs to the ancient Mediterranean and sub-Mediterranean regions (Gagnidze & Davitadze, 2000). The humid subtropical climate strongly determines local vegetation.
The average annual temperature is 13.5 °C. The average temperature in January is 4.8 °C, and in July -22.4 °C. Absolute minimum is -14 °C, and absolute maximum is +41 °C. The average precipitation is 2500-3000 mm per year. Autumn and winter are distinguished here by abundance.
In total, three plant communities were selected during the field expeditions using the route method. GPS coordinates were captured at the selected plots. Laboratory analysis, identification, and herbarization were carried at the the Institute of Phytopathology and Biodiversity in Kobuleti, Batumi Shota Rustaveli State University.
The vegetation descriptions (relevés) were made following the Braun-Blanquet approach (Mueller-Dombois & Elenberg, 1925;Poore, 1955;Müller & Schmetterer, 1974;Minnesota Department of Natural Resources, 2013). On the experimental plots, the relevés were made with fixed intervals. The constancy of all species was calculated as a percentage overall and separately for each relevé. Surveyed area size varied depending on the plant cover. In the case of tree plants, it was 400-500 m 2 , while in case of mosses -0.25-0.5 m 2 . The projective cover was determined for each plant species in all areas using the sevengrade Braun-Blanquet scale: 5 -the species has 75-100 % projective cover, 4 -50-75 %, were applied for the formal naming of the investigated plant communities.

Results and discussion
In the immediate historical past, mixed subtropical and mixed broadleaf forests with the predominance of Castanea sativa Mill., Fagus orientalis Lipsky, Quercus hartvisiana Stev., Tilia dasystyla Steven subsp. caucasica (V. Engl.) Pigott, Pterocarya fraxinifolia (Poir.) Spach, and Diospyros lotus L. were common for Kolkhis Lowland. However, at the end of the XIX century and the beginning of the XX century, many drainage channels were constructed, and mentioned plants were cut down and replaced by artificial Eucalyptus, Cryptomeria, and Cinamomum plantations. Eucalyptus was introduced for cultivation in swampy areas in coastal Adjara as a remedy against swamps and malaria mosquitoes. In particular, Eucalyptus globulus Labill. was introduced in 1895, E. viminalis Labill. -in 1900, andE. cinerea F. Muell. ex Benth. -in 1912. Cryptomeria japonica was introduced in coastal Adjara at the beginning of the XX century. After that, it has undergone complete acclimatization, and today these plants actively bloom, produce fruits and selfseedlings. Cinnamomum glanduliferum (Wall.) Meisn. was introduced as an ornamental plant in 1900.
At the end of the XX century, plantations on the investigated territories were cut down again due to different reasons. In these degraded, empty, and abandoned areas, competition between the native and alien plant taxa started in certain plant groups, characterized by lower stability.

Cryptomerietum japonicae
The mentioned territory is located in the The main tree layer of the community is differentiated into sub-layers. The specimens of Cryptomeria japonica that survived deforestation dominate in the first sub-layer and reach 20-25 m of height. The second sub-layer is outlined with self-cropped undergrowth specimens and root sprouts located on the cut logs of Cryptomeria japonica, Eucalyptus, and Cinamomum.
Eight species (Cryptomeria japonica, Frangula alnus Mill., Hedera colchica, Lespedeza bicolor Turcz., Lonicera japonica, Hydrocotyle ramiflora, H. vulgaris L., and Smilax excelsa) are naturally renewed and engaged in the formation of the basic layer of the given plant community. The local flora elements (i.e., Quercus hartwissiana Steven, Carpinus caucasica Grossh. (= Carpinus betulus L.), and Vaccinium arctostaphylos L.) are represented by very few units due to shadowing created by The appearance of Carpinus caucasica, Alnus glutinosa (L.) Gaertn., Corylus avellana L., Hedera colchica, Frangula alnus, Smilax excelsa, and Vaccinium arctostaphylos characterizing the primary phytocoenoses, allows assuming that participation of these and many other native species will increase in the future.

Eucalyptetum-viminali-globulo-cinerei
The research area is flatland, within 9-18 m a.s.l. elevation, located between 37T  Only a few specimens of the indigenous species Castanea sativa are present there. The canopy of the main layer is dense, and this defines the specific composition and structure of underlying vegetation.
In this community, herbaceous cover (the third layer) is distributed quite unevenly. It is The soil surface is more or less covered with three species of mosses (Calliergonella cuspidata, Odontoschisma denudatum, and Polytrichum strictum) and the channels -with Sphagnum cuspidatum Ehrh. ex Hoffm.
Species creating the main cover in Eucalyptetum-viminali-globulo-cinerei community have weak natural renewal capacity. Their reproduction is mainly realized through self-seeding and root sprouts.

Cinnamomo glanduliferae-Cryptomerietum japonicae
The research area is flatland located at 13- Forty-nine plant taxa were registered in this community, including 25 native and 24 aliens. Among them, 16 taxa are represented by woody plants and 33 taxa -by herbaceous ones. In contrast to the mentioned above communities, here we observed native Rhododendron ponticum L. and invasive Andropogon virginicus L. (Appendix).
This plant community is differentiated into layers and sublayers. In the first layer, the 20-30-meter trees of Eucalyptus cinerea and E. viminalis form the first sub-layer. The second sub-layer is outlined at 10-20 m height and formed by Cryptomeria japonica and Cinnamomum glanduliferum. The third sub-layer is represented by the 4-8-meter-  The natural renewal of the trees creating the main cover is weak, and reproduction is realized chiefly through self-seeding and root sprouts.
The presence of the number of alien taxa that originated from East Asia is a result of several factors, including similar climatic conditions (i.e., high humidity and precipitations, favorable temperatures during the whole year, fertile soils, etc.). In addition, it reflects the history of the introduction and cultivation of mentioned taxa and associated weeds. The species of the Mediterranean and European origin are numerous too. This is also partly determined by the phytogeographic structure of the Adjara flora.
Because of the disposition of Eucalyptus leaves, in Eucalyptetum-viminali-globulocinerei community, the shadow is lower. This results in a higher number of taxa (36 native and Floristic characteristics of some synanthropic plant communities of the Kobuleti lowland 55 aliens). There are unfavorable conditions for plants spread in two other communities; hence their number is much lower (33 native and 33 alien taxa in Cryptomerietum japonicae, and 25 native and 22 alien taxa in Cinnamomo glanduliferae-Cryptomerietum japonicae).
Despite cuttings and artificial planting of alien representatives, some indigenous woody species (i.e., Corylus avellana, Frangula alnus, Vaccinium arctostaphylos, Smilax excelsa, Quercus hartwissiana, Carpinus caucasica, Castanea sativa, Hedera colchica, etc.) still occur in this territory. Both native and alien taxa participate in the formation of the described landscape structure. In all three communities, the Lonicera japonica wraps trees and shrubs, significantly inhibiting their development. Herbaceous vegetation mainly developed under the trees canopy and is induced by it. In glades, we observed Miscanthus sinensis, which restricts the penetration and growth of other competitors.
Successional events have started in the Kolkheti Lowland in ancient times. It is a long-term process, which is still ongoing, as our observations confirmed it. Not only woody plants take part in the creation of the secondary communities in this region. Here we also found secondary meadows and some other secondary communities that will be reported in further researches.