Included here are the Caucasus Mountains. These mountains are actually composed of two separate ranges - the Greater Caucasus in the north and the largely volcanic Lesser Caucasus in the south.
Caucasian Oak-Hornbeam Forest
The remaining natural or semi-natural remnants of these forests such as in Greater Caucasus around Tbilisi show that they had an upper canopy dominated by the endemic or near endemic Carpinus caucasica (Betulaceae) and Quercus iberica (Fabaceae) reaching heights of up to about 10 m. A sub-canopy about 6 m high largely dominated by Carpinus caucasica is usually present. Shrub layer species include Acer campestris, Cornus mas, Corylus avellana, Crataegus monogyna, Malus orientalis, Prunus divaricata, Rosa canina, Viburnum avellana and the endemic Lonicera caucasica (Caprifoliaceae) and Pyrus caucasica (Rosaceae) and generally reach a height of about 3 m. Below this is a rich herb layer comprising species like Arum albispathum, Campanula rapunculoides, Geum urbanum, Polygonatum verticillatum and the endemic Cyclamen vernum (Primulaceae), Galanthus caucasicum (Alliaceae) and Primula woronowii (Primulaceae). However, much of these forests have now been converted to secondary deciduous scrub with species such as Berberis vulgaris, Cotinus coggygria, Paliurus spina-christi, Spiraea hypericifolia and the endemic Amygdalus georgica (Rosaceae).
Caucasian Arid Pistacia-Juniperus Woodland
Woodland dominated by Juniperus foetidissima, J. polycarpus, J. rufescens and the deciduous Pistacia mutica are important in the dryer eastern areas, especially in eastern Georgia. They also extend westward to Tbilisi and on through the Mtkvari River Valley to the Meskheti region. They are largely composed of small trees (ca. 8 m) and usually have a well-developed shrub layer up to 3 m high. Typical shrubs are Cerasus microcarpa, Paliurus spina-christi, Berberis iberica, jasminum fruticans, Lonicera iberica and Rhamnus pallasii. Among the many herbaceous ground layer species are Campanula hohenackeri, Cleistogenes bulgarica, Helianthemum salicifolium, Falcaria vulgaris, Lasiagrostis bromoides and the endemic Dictamnus caucasicus (Rutaceae) and Polygala transcaucasica (Polygalaceae). However, these woodlands rarely have a closed canopy and often have a parkland character especially on flatter terrain.
Caucasian Mixed Broad-Leaved Forest
In the western Caucasian (Colchic) zone up to an altitude of about 600 m humid, thermophilous mixed forest occurs dominated by Castanea sative, Fagus orientalis, Quercus hartwissiana, Zelkova carpinifolia and the Caucasian endemic Carpinus caucasica (Betulaceae). The under story is typically Colchic with species such as Laurocerasus officinalis, Rhododendron ponticum and the endemic Ruscus colchicus (Ruscaceae). Typical lianas are Hedera helix, Vitis sylvestris and the endemic or near endemic Dioscorea caucasica (Dioscoreaceae) and Hedera colchica (Araliaceae).
Caucasian Sweet Chestnut Forest
Deciduous forests dominated by Castanea sativa grow luxuriantly on marls, chalky stone and volcanic sandstone. They are mainly confined to an altitudinal range of between 200–700 m and mainly occur on northern slopes. Other characteristic species include Achillea biserrata, Smilax excelsa and the endemic Hedera colchica (Araliaceae). The rich shrub layer can have coverage of up to 60% and typically includes Laurocerasus officinalis, Rhododendron luteum, Vaccinium arctostaphylos and the endemic Ilex colchica (Aquifoliaceae). These forests are widespread and can be found, for example, in the Hamza Quarter of the Bozkurt District and in the Bahce and Sen Quarters. Other associated endemic taxa include Aristolochia pontica (Aristolochiaceae), Digitalis ferruginea subsp. ferruginea (Scrophulariaceae) and Trachystemon orientalis (Boraginaceae).
Caucasian Subalpine Oak and Birch Elfin Forest
At sub alpine altitudes (2100-2400 m) of the western Caucasian (Colchic) zone, dwarf woodlands of oak and birch occur. The main species are Quercus pontica and Caucasian endemic birches Betula medwedewii and B. megrelica (Betulaceae). Other species include various endemic Tertiary relicts like Corylus colchica (Corylaceae), Epigaea gaultherioides (Ericaceae), Rhododendron smirnowii and R. ungernii (Ericaceae).
References
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Szafer, W. 1966. The Vegetation of Poland. Pergamon Press.
Tumajanov, I. I. 1971. Changes in the Great Caucasus Forest Vegetation during the Pleistocene and Holocene. In: Plant Life of South-West Asia. Eds. P. H. Davies, P. C. Harper & I. C. Hedge. The Botanical Society of Edinburgh.
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Zazanashvili, N., Gagnidze, R. & Nakhutsrishvili, G. 2000. Main types of vegetation zonation on the mountains of the Caucasus. Acta Phytogeographica Suecica, 85: 7-16.