Wednesday, December 7, 2011

VEGETATION OF GEORGIA / Kvachakidze, Revaz

VEGETATION OF GEORGIA
Kvachakidze, Revaz

The structure and change of the Georgian vegetation have been considered throughout the geological history of the territory of the country from the Carbon period of the Paleozoi to this day.The avialable paleogeographical and paleobotanical sources have been used.
In the II part of the book phytocenological characteristic of the principal vegetation types of Georgia – Forests, Scrub, Meadows,Steppes, Semi-Deserts, Wetland vegetation.

Summary

The history of the vegetational cover of Georgia runs to 300 million years. From the Carbon period of the Paleozoic era to the end of the Mezozoic era the islands of the Tetis Ocean (the initial stage of the mountains of the Greater and Minor Caucasus) were covered with the rich vegetation of a tropical type. The ancient plants, representatives of Lepidodendraceae, Sigillariaceae, Calamitaceae, Cordiataceae, Bennettitaceae, Caytoniaceae, Cicadaceae, Ginkgoaceae, Araucariaceae and other families took part in its formation.

Beginning from the Tertiary period of the Kainozoi (Paleocene, Eocene) the overland territory of Georgia (the Greater and Minor Caucasus) considerably extended and the tropical climate was gradually replaced by the subtropical climate. A Substantial change in the local vegetational cover took place. It led to the replacement of the local tropical plants by subtropical, mainly evergreen vegetation, formed by species from Pteridospermae, Palmaceae, Pinaceae, Magnoliaceae, Lauraceae, Myrtaceae, Taxodiaceae and some other taxons.
In the Oligocene when the active processes of formation of folded mountains of the Greater and Minor Caucasus took place, the representatives of the Turgai fl ora – coniferous and leaf-shedding species took root in the local subtropical evergreens.


Since the Miocene (25 million years ago) the vegetational cover of Georgia entered a new phase of its development. The vegetation in the Miocene was rather rich and diverse. It was formed by the phytocenoses of evergreen vegetation, their dominants being the representatives of Sequoia, Cedrus, Libocedrus, Tsuga, Abies, Picea, Pinus, Ficus, Laurus, Cinnamomum, Myrica, Liquidambar, Magnolia, Camellia and other genera. The phytocenoses of leaf-shedding plants their dominants being ancient species of Platanus, Quercus, Castanea, Carpinus, Acer, Alnus, Salix, Populus, Pterocarya and other genera were also part of the vegetational cover. There grew some modern species (Abies nordmanniana and others) as well. In the Miocene the mountains of the Greater and Minor Caucasus reached the height of 1000-1500 m. above sea level. Distribution of the vegetation on the mountain slopes was of vertical and zoning character: subtropical evergreen forests occupied mainly the lower zone, while the coniferous and leaf-shedding forests – the upper zone.


In the Pliocene (10-1 million years ago) the territory of Georgia was mainly of modern form. A gradual change of the climate (a fall in the temperature) caused considerable alterations in the structure of the local vegetation. The plants immigrated from neighbour and distant countries greatly contributed to it. Towards the end of the Pliocene (4-1 million years since) the structure of the vegetation and the character of distribution of main sintaxons on the territory of Georgia approached the modern ones. In the Late Pliocene and Early Pleistocene the territory of Georgia was in fact completely covered by forests.
In Western Georgia (Kolkheti) the forest vegetation still had the plant species which nowadays are not naturally found in Georgia (the plants, having their related forms spread in East-Asian, Himalayan, North-American and Mediterranean subregions of Golarctic), specifi cally the species of the genera of Sequoia, Metasequoia, Cryptomeria, Cunninghamia, Cedrus, Libocedrus, Taxodium, Tsuga, Thuja, Magnolia, Liquidambar, Carya, Mahonia, Cinnamomum, Aesculus, Platanus, Robinia and others. Some of them were the dominants of forest associations. On the slopes of the Caucasian mountains vertical belts were developed: the lower belt was formed by subtropic (mainly evergreen) forests and the upper belt – by coniferous and leaf-shedding forests. In Eastern Georgia with the climate being comparatively dry and more continental the evergreen species were not numerous. The lower part of the mountain slopes and the plain were partly covered by arid forests (the dominants – Pistacia mutica, Celtis caucasica, Juniperus foetidissima, J.polycarpos) and hemixerophyl forests (the dominants – the species of Quercus etc.). In the same place a big territory was already covered by the steppe vegetation (the dominants – the species of Artemisia, Botriochloa, Stipa, Festuca etc.).


In the Pleistocene (the last one million years) especially in its glacial epochs the vegetation of Georgia lost a great number of thermophilic species of the Tertiary forest fl ora. In Western Georgia (Kolkheti - due to its comparatively warm an humid climate several species of evergreens survived: Laurus nobilis, Laurocerasus offi cinalis, Rhodo¬dendron ponticum, Rh. ungernii, Rh.smirnowii, Ilex colchica, Buxus colchica, Ruscus ponticus, R.colchicus, Hedera colchica etc. These species remain the dominants of local relict forest cenoses to this day. Of the coniferous tertiary species survived Abies nordmanniana, Picea orientalis, Pinus pithyusa, Taxus baccata. They are also the dominants of the local relict coniferous forests. In Western Georgia the tertiary forests (coniferous and leaf-shedding) enlarged the area and strengthened their positions. They settled on the territory of the Iori Upland, formed in the period.
















The majority of tertiary heat-loving leaf-shedding species also became extinct. Only few species survived – Castanea sativa, Zelkova carpinifolia, Quercus hartwissiana, Q.imeretina, Q.pedunculifl ora, Q.pontica, Betula medwedewii, Alnus barbata, Populus canescens, Pterocarya pterocarpa, Rhododendron luteum, Vaccinium arctostaphylos, Hypericum androsaemum, H.inodorum etc. These dominating relict species and the young Caucasian leaf-shedding plants (Fagus orientalis, Carpinus caucasica, Quercus iberica, Betula litwinowii etc.) formed in the Pleistocene the modern leaf-shedding forests of Georgia. From the local (Caucasian) and immigrated herbaceous species the meadow vegetation of Georgia was formed, which occupied vast space in subalpine and alpine belts of the Greater and Minor Caucasus. On the plain of Western Georgia the steppe area got expanded. Its phytocenoses were formed of the local tertiary and immigrated to Georgia species in the Pleistocene (from arid neighbour regions).
















The phytocenotic variety of forest formations is not identical. Fagus orientalis forests is characterized by the highest phytocenotic variety – 52 associations, which makes up almost half of the Georgian forests having wide altitudinal and horizontal prevalence (area). Other forest formations are represented by the following number of associations.
In Holocene (the last 12-10 thousand years) the structure of the local vegetation underwent a considerable change due to a periodical change in the climate.
In the Middle Holocene the natural structure of the vegetation and the character of distribution of the vegetation syntaxons of Georgia was finally developed (except for the forests; the natural vegetation is formed by shrubs, meadows, steppes, substeppes and marsh types of vegetation).
















After the Middle Holocene the vegetation of Georgia underwent a change due to human economic activities. The scale of anthropogenic changes of the natural (virgin) vegetation kept increasing. The results of these changes consist in the following:
1. A quantity of forests decreased (nowadays the forests cover 35-38% of the total territory of Georgia, mainly the slopes of the Greater and Minor Caucasus);
2. A quantity of virgin forests greatly declined making up 18-20% of all forests (about 400000 hectares).
3. The structure of the economic vegetation (forests, meadows, steppes, substeppes) is more or less disturbed, badly decreased is the productiveness of phytocenoses.


In the II part of the book phytocenological characteristic of the principal vegetation types of Georgia – Forests, Scrub, Meadows, Steppes, Semi-Deserts, Wetland vegetation. In the vegetation of Georgia forests are dominated. 98% of them are mountain forests, located on the slopes of the Greater and Lesser Caucasus ranges, 100 (400) – 2300 (2600) m above sea level. In the plain (Kakheti Lowland, Iberian plain, plateaux) natural forests remain in small areas, locally, most part of which are protected nowadays (nature reserves and national parks).


Abies nordmanniana forests – 32 associations, Carpinus caucasica – forests – 28 associations, Quercus iberica forests – 25 associations, Pinus sosnowskyi forests – 18 associations, Picea orientalis forests – 17 associations, Batula litwinowii forests – 16 associations, Castanea sativa forests – 15 associations, Quercus macranthera forests – 8 associations, Acer trautvetteri forests – 8 associations, Alnus barbata, A.incana forests – 8 associations, Juniperus foetidissima, J.polycarpos forests – 11 associations, Zelkova carpinifolia forests – 6 associations, Quercus pedunculi flora forests – 6 associations, Pistacia mutica forests – 5 associations, Quercus imeretina forests – 4 associations, Pinus pithyusa forests – 4 associations, Fraxinus excelsior forests – 4 associations, Populus tremula forests – 3 associations, Populus canescens, P. nigra forests – 3 associations, Quercus dschorochensis forests – 2 associations, Taxus baccata forests – 1 association, Salix excelsa forests – 1 association.



A brief characteristics (diagnostics) of forest associations given in the work embraces dominants and characteristic species (according to layers), structure (layer structure, density of canopy, understorey and grass cover), habitat conditions (altitude, slope exposition and inclination, soil capacity and humidity). Other vegetation types of Georgia are characterized – Scrub, Meadows vegetation, Steppe vegetation, Semi-Deserts vegetation, Wetland vegetation. The phytocenotic diversity of the Georgian forests is high showing itself in the forests typologic variety. 277 associations of 23 formations have been registered in all.




Type of material:
Book (Print, Microform, Electronic, etc.)
Personal name:
Kvachakidze, Revaz
Author:
Kvachakidze, Revaz
Main title:
Vegetation of Georgia
Title/Heading:
Saqartvelos mcenareuloba [geo]
Abbreviated Title:
Saq. mcen. [geo]
Alternate Title:

Similar Titles:

Tags:

Published/Created:
Tbilisi

The Georgian National Academy of Sciences , 2009
Related names:
Kakha Jashagashvili
Description:
154 p. ; 21 cm.

Includes bibliographical References (p. 146 - 154)
Subjects:
Forests / Plants / Vegetation / Phytocenoses
Subject Headings:
Phytocenotic diversity / phytocenological characteristic

Kolkheti / Georgia / The Greater and Minor Caucasus
Subject/Content:
The structure and change of the Georgian vegetation

Have been considered throughout the geological

History of the territory of the country from the Carbon

Period of the Paleozoi to this day.The available

Paleogeographical and paleobotanical sources have

Been used. In the II part of the book phytocenological

Characteristic of the principal vegetation types of

Georgia – Forests, Scrub, Meadows,Steppes, Semi-

Deserts, Wetland vegetation.
ISBN:
978-9941-0-1206-8
Dewey class no.:
581.9(479.22)+ 581.524+582.382.4+582.382.8
Language code:
geo [Georgian]

eng [English]
Country code:
gs [Georgia (Republic)]
Geographic area code:
gs [Georgia (Republic)]
Statement of

Responsibility:
Prof. Revaz Kvachakidze;

Tbilisi Botanical Garden And Institute Of Botany
Abstract/Summary:
The history of the vegetational cover of Georgia runs

To 300 million years. From the Carbon period of the

Paleozoic era to the end of the Mezozoic era the islands

Of the Tetis Ocean (the initial stage of the mountains

Of the Greater and Minor Caucasus) were covered

With the rich vegetation of a tropical type. The ancient

Plants, representatives of Lepidodendraceae,

Sigillariaceae, Calamitaceae, Cordiataceae,

Bennettitaceae, Caytoniaceae, Cicadaceae,

Ginkgoaceae, Araucariaceae and other families

Took part in its formation.
Notes:
Softcover

The Georgian National Academy of Sciences

Saqartvelos mecnierebata erovnuli academia
DDC/UDC Subject:
Forests / Plants / Vegetation / Phytocenoses

Biology / Life sciences / Geobotany
UDC Class Number:
582.382.4
Description:
Lepidodendraceae
UDC Class Number:
582.382.8
Description:
Sigillariaceae
Total Copies:
2
Available:
2
Call Number:

Request in:
Scientific Library of Institute of Botany of Ilia State University


Status:
Available





Download