Ecoregions

Euxine-Colchic deciduous forests

Content Cover Image

Çamilhemsin Valley, near Trabzon, Turkey Photograph by Jeffrey England

Extending along the southern Black Sea coast, the vegetation in the Euxine-Colchic deciduous forests ecoregion ranges from temperate rainforest to coastal bottomland forests, peatlands and coastal sand dunes. The old-growth forests are home to one of the largest brown bear populations in Europe, and the migratory populations of many waterfowl, passerines, and raptors fly through the eastern end of the region. The draining of wetland habitat for agriculture, logging, and poaching are among the greatest threats to the flora and fauna.

Location and General Description

caption WWF


Running along the southern and southeastern coasts of the Black Sea, this ecoregion extends from Turkey’s Istiranca Mountains in the west to the Abkhazia region of Georgia in the east. The most humid region in the Caucasus, it can be divided into two main sub-provinces, distinguished according to their precipitation regimes. The eastern, or Colchic, region is highly humid with an average of 1500 to 2500 millimetres (mm) annual precipitation and a maximum in excess of 4000 mm. The western, or Euxinic, region is less humid and receives between 1000 and 1500 mm of average annual precipitation.

Phytogeographers accept the Melet River, which empties into the Black Sea near Ordu, as the boundary between the Colchic and Euxine sub-provinces. The high ridges of the Eastern Black Sea Mountains end near here and the low ridges of the Western Black Sea Mountains begin. The high mountains exercise a predominant influence on the climate, and thus on the vegetation.

In geological terms, this is a young region that began to form in the middle of the Holocene period 5-6 thousand years ago. From a geomorphological perspective, it is an accumulating plane with a high hydrographic net. The large rivers that cross it are fed by snow, rain, groundwater, and glacial melt, and the small rivers are marsh types. There are several lakes in the region, the most significant of which is Paliastomi Lake, which has a water table of 1,820 hectares (ha), 3,2-metre depth. The lakes are located in the coastal areas and most are of lagoon origin. However, in the central part of the coastal plain, the lakes originated in rivers and have been subject to significant anthropogenic impacts.

The principal rivers are the Sakarya, Kizilirmak, Yesilirmak, Firtina, Coruh, and Rioni rivers (from west to east). All of these rivers carry alluvial deposits from the mountains to the coast, where hardwood and softwood bottomland forests occur. The most important soils are alluvial, yellow, yellow-podzolic, red earth, rendzila, forest brown, mountain meadow and andosols. Colchic evergreen species grow on all of these soil types.

During the Pleistocene, the Colchic region served as an important refuge for temperate east-European flora. From the high precipitation levels, it can be concluded that broadleaf deciduous forests constitute the main vegetation type. Oriental beech (Fagus orientalis) is the main canopy species, with sweet chestnut (Castenea sativa), sessile oak (Quercus petrea ssp. iberica), Acer cappadocicum (syn. A. laetum), Caucasian elm (Zelkova carpinifolia), limes (Tilia spp.) and Caucasian wingnut (Pterocarya fraxinifolia) also penetrating to the canopy. An interesting feature of this forest type is the evergreen but mesomorphic broadleaf understory, including species such as common holly (Illex aquifolium), Hedera helix, Rhododendron ponticum, R. ungernii, R. smirnowii, R. caucasicum, cherry-laurel (Prunus laurocerasus), Caucasus box (Buxus colchica), common box (B. sempervirens), and Ruscus colchicus. Most of these species are considered, in a European context, to be Tertiary relicts. In the humid lowland forests (up to 1,000 m) they are generally dominated by Castenea sativa and above this belt Fagus orientalis tends to be dominant. Another characteristic formation in this ecoregion is the common alder (Alnus glutinosa) forest found along streams.

The western forests tend to support a higher diversity of woody species, with up to 12-15 different trees per 500 square meter (m2) in the Bolu, Zonguldak and Bart?n regions. The eastern forests are more commonly old growth forests with a lower species diversity.

Biodiversity Features

Mature intact forests, including rare coastal temperate rainforests, are one of the region’s most outstanding natural features. High in biodiversity, they are notable for their pristine wilderness and scenic beauty. These forests provide important habitat for large mammals, including one of the largest populations of brown bear (Ursus arctos) in Europe. Other important species found in the lowland forests are jackal (Canis aureus), lynx (Lynx lynx), red deer (Cervus elaphus), and roe deer (Capreolus capreolus).

The bottomland forests of the Black Sea coast constitute another noteworthy feature. This formation is extremely rare throughout Europe as it only occurs in coastal delta areas.

A number of globally threatened bird species migrate through, nest or winter in this area, including the dalmatian pelican (Pelecanus crispus), pygmy cormorant (Phalacrocorax pygmaeus), white-headed duck (Oxyura leucocephala) and ferruginous duck (Aythya nyroca). Other noteworthy species include the white pelican (P.onocrotalus), black stork (Ciconia nigra), white stork (C. ciconia), greater flamingo (Phoenicopterus roseus), bewick's swan (Cygnus bewickii), red-crested pochard (Netta rufina), demoiselle crane (Anthropoides virgo), and numerous other ducks, geese, herons, and gulls.

The eastern end of the ecoregion is an important transit and refueling area for large migratory populations of waterbirds, passerines and raptors. This migratory pathway is known as the ‘East Black Sea Migration Route’ and birds from breeding populations in Fenno-Scandinavia and Russia navigate through here. Some of the migratory birds of international conservation importance that pass through in sizable numbers include the globally threatened eastern imperial eagle (Aquila heliaca), the black stork (Ciconia nigra) and the crane (Grus grus).

Another rare and threatened habitat type is a peatland formation in Istanbul. Originally covering 95,000 ha, this peatland now covers barely 2,000 ha. Nonetheless, it represents the most important peatland area of Eastern Europe and the Eastern Mediterranean region.

The 23 coastal dune systems in Turkey constitute an additional valuable habitat type. Among these, the dunes of Kasatura-Gumusdere (Istanbul), Sarikum (Sinop), and Terme (Samsun) deserve special interest due to the richness of rare dune plant species they support.

Another unusual feature is the enclave of Mediterranean vegetation found in the Coruh River Basin on the lower flanks of the Lesser Caucasus Mountains. While the Mediterranean formation that is apparent on the western Black Sea coasts is characterized by sclerophyllus shrubs, this eastern enclave is a deciduous formation and is therefore referred to as "pseudo maquis" vegetation. The eastern strawberry-tree (Arbutus andrachne) and Phillyrea latifolia are the main species of note.

Current Status

Very little of the original Colchic forest remains, primarily due to uncontrolled logging and urban and agricultural development. The three bottomland forest stands at ??neada (K?rklareli), Sar?kum (Sinop) and Hac?osman (Samsun) have been designated as Strict Nature Reserves.

The Ramsar Convention on Wetlands characterizes the Kolkheti wetlands in Georgia as being of international importance for biodiversity. Many of the bird species observed in this ecoregion nest, winter or migrate through here. In addition, there are several Important Bird Areas (IBAs). The Igneada bottomland forests support a breeding population of Ciconia nigra and a high number of C. ciconia and other migratory raptors. The Bosphorous region constitutes a major bottleneck for migratory birds, and Sarikum lake supports large numbers of wintering waterfowl and Oxyura leucocephala. The Kizilirmak Delta hosts breeding populations of Pelecanus crispus, purple heron (Ardea purpurea), Ciconia nigra, spoonbill (Platalea leucorodia), gadwall (Anas strepera), Netta rufina, Aythya nyroca, crane (Grus grus), stone-curlew (Burhinus oedicnemus), collared pratincole (Glareola pratincola) and a high number of wintering waterfowl. The Yesilirmak Delta supports breeding populations of night heron (Nycticorax nycticorax), little egret (Egretta garzetta), and glossy ibis (Plegadis falcinellus).

Protected areas in the ecoregion

Name District Status IUCN Cat. Area (he.) Point of Interest Comments
Kure Mountains Bartin- Kastamonu National Park II 34.018 Unique carstic system, wildlife, old-growth forest formation One of the largest protected areas in Turkey. Represents a unique and old-growth forest formation.
Sakagolu Bottomland Forest Kirklareli Nature Reserve Ia 1.345 Habitat diversity, bottomland forest, bird diversity One of the most important nature reserve both with its diversity and large size. Its strict status creates management problems.
Kasatura Bay Kirklareli Nature Reserve Ia 329 Only Black Pine population in the Euxinic province of the Thrace Peninsula Gene conservation status seems more proper for this degraded small population of the black pine
Beykoz Pineland Istanbul Nature Reserve Ia 46 Only known seaside population of the Abies bornmulleriana Gene conservation status seems more proper for this degraded small population of the fir.
Demircionu Bolu Nature Reserve Ia 430 Western black sea coastal forest ecosystem Only protected area representing the western Black Sea coastal forest ecosystem but area is declared after the intensive logging in 1994.
Kavakli Zonguldak Nature Reserve Ia 334 Woody species diversity, rich wildlife Represents one of the most diverse and intact forest of Turkey. But has small area.
Citdere Zonguldak Nature Reserve Ia 721 Woody species diversity, rich wildlife Represents one of the most diverse and intact forest of Turkey. But has small area.
Sarikum Sinop Nature Reserve Ia 831 Habitat diversity, bottomland forest Important site with its habitat diversity and bird richness. Its strict status creates management problems.
Haciosman Samsun Nature Reserve Ia 121 Habitat diversity, bottomland forest Important site with its habitat diversity and bird richness. Its strict status creates management problems.
Camburnu Artvin Nature Reserve Ia 180 One of the few known seaside population of Scots Pine in Turkey Small size, surrounding settlements are the main negative effects.

Types and Severity of Threats

The lowland forests have been heavily logged due to forest management strategies that emphasize wood production. The same factor is responsible for the destruction of some old-growth forest patches. The destruction of peat formations by draining and industrial peat mining threatens the habitat diversity upon which many bird communities depend.

About 60 % of the Colchic wetlands have been drained for agricultural production (especially tea and citrus plantations) and for rural development projects. The greatest threat faced by the Kolkheti wetlands is from the transportation of oil products and the operations of the oil terminals on Georgia’s Black Sea coast. Similarly, along Turkey’s eastern Black Sea coast, the "Black Sea Motorway" has destroyed all but the smallest patches of coastal vegetation.

Wildlife poaching in established reserves is a significant problem. The population of Capreolus capreolus has been greatly reduced even though extensive areas of suitable habitat exist. Northbound migratory birds are hunted with nets upon their arrival on the coast.

Justification of Ecoregion Delineation

This ecoregion is mostly equivalent to the lowland and montane Black Sea deciduous mixed forests found on the Pontian uplands. An area of northern Anatolian relic oak and mixed sub-humid forests is also included, truncated at the southern boundary of the ecoregion (at the boundary with the northern Anatolian conifer and deciduous forests ecoregion). Modifications and additions consist of including the hygro-thermophilous mixed deciduous broadleaf forests (and portions of swamp forests) in the eastern sections of the ecoregion as well as an area of the montane Black Sea unit in European Turkey. The extreme eastern portion of montane Black Sea deciduous mixed forest has been classified as the Caucasus mixed forests ecoregion.

Additional Information on this Ecoregion

Further Reading

  • Atalay, ?. 1994. Türkiye Vejetasyon Co?rafyas?. Ege Universitesi Bas?mevi. ?zmir, Turkey.
  • Bohn, Udo, G. Gollub and C. Hettwer. 2000. Reduced general map of the natural vegetation of Europe. 1:10 million. Bonn-Bad Godesberg.
  • Boulos, L., A.G. Miller and R.R. Mill. 1994. Regional overview: South West Asia and the Middle East. In S.D. Davis, V.H. Heywood and A.C. Hamilton, editors, Centres of Plant Diversity. A Guide and Strategy for their Conservation. Volume 1. Europe, Africa, South West Asia and the Middle East. pp. 293-308. IUCN Publications Unit, Cambridge, U.K.
  • Box, E. O., K. Fujiwara, G. Nakhutsrishvili, N. Zazanashvili, R. J. Liebermann and A. Miyawaki. 2000. Vegetation and landscapes of Georgia (Caucasus) as a basis for landscape restoration. Bulletin of the Institute of Environmental Science and Technology 26, 1: 69-102
  • Byfield, A.J. and N. Ozhatay. 1995. Towards the conservation of Turkey’s northern sand dunes. Do?al Hayat? Koruma Derne?i. Istanbul, Turkey
  • Gavashelishvili A. 1998. Results of ornithological inventories along the pipeline and around the Supsa Terminal. Report to the GPC. 65 pp
  • Gavashelishvili, A. 1996. Birds of Georgia/Natura Caucasica 1:1-75
  • Guidotti, G., P. Regato, and S. Jimenez-Caballero. 1986. The major forest types in the Mediterranean. World Wildlife Fund, Rome, Italy.
  • Kolakovsky, A.A. 1974. Vertical belts of Colchic forest vegetation in the Tertiary period. Trudy Tbilisskogo Instituta Lesa, Tbilisi, Georgia, 21: 98-116 (in Russian)
  • Kurdo?lu, O. 1996. Do?u Karadeniz’in Do?al Ya?l? Ormanlar?. Do?al Hayat? Koruma Derne?i. ?stanbul, Turkey.
  • Magni, G. and M. Yarar. 1997. Important bird areas in Turkey. dogal Hayati Koruma Dernegi. Istanbul, Turkey. ISBN: 9759608170
  • Quézel, P., M. Barbéro, and Y. Akman. 1980. Contribution à l’étude de là végétation forestière d’Anatolie septentrionale. Phytocoenologia 8:365-519.
  • Research Association for Rural Environment and Forest. 2000. Turkiye’nin Tabiati Koruma Alanlari. Donmez Ofset. Ankara, Turkey.
  • Zazanashvili, N. 1999. On the Colchic vegetation. Pages 181-197 in F. Klotzli and G. R. Walther, editors. Conference on recent shifts in vegetation boundaries of deciduous forests, especially due to general global warming. Basel, Switzerland. ISBN: 0817660860

Disclaimer: This article contains information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

 

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Citation

Fund, W. (2014). Euxine-Colchic deciduous forests. Retrieved from http://www.eoearth.org/view/article/152691

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