Danube Delta Coastal Dunes and Strandline

In the upper littoral zone the pioneer vegetation is typically dominated by Crambe maritima. This zone is moderately saline and vegetation is usually open with very limited ground cover. Other characteristic species include Agropyron junceum, Argusia sibirica, Atriplex hastata, Centaurea arenaria, Eryngium maritima, Euphorbia seguierana, Glaucum flavum, Leymus sabulosus, Medicago falcata, Polygonum maritimum, Salsola ruthenica and Secale sylvestris. However, on newly created sandbars on the Ukrainian side, a different assemblage of pioneer species occurs. Here the main species are Artemisia annua, Bidens tripartita, Chenopodium album, C. ambrosioides, C. rubrum, Echinochloa crus-galii, Polygonum patulum, Rumex maritimus and Suaeda prostata. At slightly higher levels of newly developed foredunes Elymus giganteus often becomes the dominant species. In this zone the vegetation becomes slightly more diverse with additional species such as Anchusa leptophylla, Artemisia arenaria, Centaurea odessana, Cynanchum acutum, Gypsophila perfoliata, Lactuca tatarica, Leymus arenarius, Linaria genistifolia, Linum austriacum, Medicago kotovii, Picris rigida and the endemic or near endemic Cakile euxina (Brassicaceae) and Syrenia cana (Brassicaceae). On the high dunes above the littoral zone there are a variety of dune communities, but some of the characteristic species include Carex colchica, Poa bulbosa, Secale sylvestris and the endemic or near endemic Alyssum borzaeanum (Brassicaceae) and Festuca beckeri (Poaceae). Bushes of Elaeagnus angustifolia and Hippophae rhamnoides are also characteristic. On the old dunes of the Zhebryansky Ridge (Ukraine) there are a number of unusual dune associations rich in endemic or near endemic species. On the riverside sand the dominant species include Artemisia scoparia, Euphorbia seguierana, Leymus arenarius, Secale sylvestre together with the endemic or near endemic Artemisia tschernieviana (Asteraceae), Asperula setulosa (Rubiaceae), Polygonum novoascanicum (Polygonaceae) and Tragopogon borysthenicum (Asteraceae). Other more widespread species include Apera maritima, Centaurea orientalis, Cerastium sivashicum, Condrilla juncea, Polypogon monspeliensis and the endemic or near endemic Arenaria zozii (Caryophyllaceae), Corispermum ucrainicum (Chenopodiaceae) and Syrenia cana (Brassicaceae).

Danube Delta Dune Forest

This diverse forest can be found in the Caraorman and Letea dune complexes. The Caraorman (or Black Forest) is aptly named since the old oaks with their impressive branches and other rich vegetation give their sub canopies a very dark appearance. On the old dunes of Letea, which is the largest maritime sandbank in the Danube Delta, they occur as a series of bands up to 250m long and 10m wide with trees up to 35 m in height. The main trees include Fraxinus ornus, F. angustifolia, F. pallisae, Populus alba, P. nigra, Pyrus pyraster, Quercus pedunculiflora, Q. robur, Tilia tomentosa species of Ulmus and the occasional Alnus glutinosa. Among the shrubs are Berberis vulgaris, Cornus mas, C. sanguinea, Crataegus monogyna, Euonymus europea, Hippophae rhamnoides, Rhamnus frangula, R. catharctica, Viburnum opulus species of Tamarix and occasional Corylus avellana. A distinctive feature is the abundance of climbing plants including Clematis vitalba, Humulus lupulus, Periploca graeca and Vitis sylvestris. In fact, the many creepers and climber plants give these forests an almost subtropical aspect. In spring, the ground is carpeted with Convallaria majalis, while other ground layer species are likely to include Allium ursinum, Cardamine bulbifera, Epipactis helleborine, Equisetum sylvaticum, Euphorbia amygdaloides, Galium odoratum, Geranium phaeum, Viola odorata and many more. Plants found in these forests considered to be rare and threatened in this part of the world include Convolvulus persica, Ephedra distachya, Merendera sobolifera, Plantago coronopus and Petunia parviflora.

Euxine Dunes

Dune vegetation in the Euxinian zone of the Black Sea is varied and complex and include many endemic species. The summaries below are based on studies carried out on the coasts of Bulgaria and Turkey. 

Euxine Dunes Bulgarian Coast (Tzonev et al. 2005)

The western (Bulgarian) Black Sea coastal Euxinian province has been divided into two regions: Southern coastline and Northern coastline separated by the Cape Emine headland. Kamchiiski sands lies in the southern zone.

Strandline or Pioneer Zone
The pioneer zone is typically characterised by the succulent species Salsola ruthenica and the Euxine endemic Cakile maritima subsp. euxina. Other characteristic taxa may include Crambe maritima, Eryngium maritimum, Euphorbia peplis, Glaucium flavum, Polygonum maritimum and Xanthium italicum.  The association is found throughout much of the Black Sea as well as around the Sea of Marmara and the northeastern part of the Aegean Sea.

Embryonic dune vegetation
The main dune former here is the Pontic species Leymus racemosus subsp. sabulosus. Among associated species Eryngium maritimum and Xanthium strumarium subsp. italicum are very common, Lactuca tatarica and Salsola ruthenica are common, but Ammophila arenaria, Elymus farctus, Crambe maritima are of limited presence. However, Xanthium strumarium is an alien, invasive species introduced from America. Other species that may be encountered include Alyssum hirsutum subsp. caespitosum, Chondrilla juncea, Corispermum nitidum, Crepis foetida subsp. foetida, Euphorbia peplis, Euphorbia paralias, Galilea mucronata, Leontodon crispus, Pancratium maritimum, Plantago scabra, Polygonum maritimum, Sonchus arvensis subsp. uliginosus, and the Pontic elements Medicago falcata subsp. tenderiensis and Jurinea albicaulis subsp. kilaea. Other species such as the Balkan near endemic Silene thymifolia and the Pontic species Centaurea arenaria subsp. borysthenica, are now very rare.  This association is distributed along the entire Bulgarian coastline. A similar association is distributed along the most southerly parts of the western Black Sea coast (Turkey), the northern Sea of Marmara coast, and the northernmost shoreline of the Aegean Sea.

Shifting dune vegetation
The main species here are Ammophila arenaria subsp. arundinacea and the pontic species Medicago falcata subsp. tenderiensis. Other typical species include Centaurea arenaria, Elymus farctus, Eryngium maritimum, Leymus racemosus subsp. sabulosus, Lactuca tatarica and Silene thymifolia. The association has a western-pontic character, defined by a considerable occurrence of the Pontic taxa Centaurea arenaria subsp. borysthenica and the Balkan near endemic Silene thymifolia. Other less common taxa include Alyssum minutum, Alyssum hirsutum subsp. caespitosum, Chondrilla juncea, Convolvulus persicus, Crambe maritima, Erysimum diffusum, Euphorbia seguierana, Festuca arenicola, Glaucium flavum, Linaria genistifolia, Marrubium peregrinum, Scabiosa argentea, Secale sylvestre, Silene conica subsp. conomaritima, Stachys atherocalyx, Stachys maritima, Xanthoria parietina and the Balkan endemics Alyssum borzaeanum, Astragalus onobrychis subsp. scorpili and Verbascum purpureum. However, species composition appears to have been altered by human impact and may be responsible for the absence of certain obligate psammophytes such as Euphorbia peplis, Medicago marina and Stachys maritima.

Fixed dune vegetation
Fixed dune vegetation on the Bulgarian coast can be divided into at least three associations – one characterised by Artemisia campestris and east Balkan-Anatolian endemic Aurinia uechtritziana, one characterised by Carex ligerica and Stachys atherocalyx, and one by Ephedra distacha and the Balkan near endemic Alyssum borzaeanum.

Artemisia campestris - Aurinia uechtritziana Association
In Bulgaria this occurs north of Kamchia River mouth, and in fact, the presence of East Balkan endemic species (Verbascum purpurem and Silene thymifolia), and pontic elements such as Cionura erecta, Jurinea albicaulis subsp. kilaea and Silene euxina, makes this association endemic to the western Black Sea coast. Strong winds make the ridges much drier and more unstable but providing habitat for annual species such as Coryspermum nitidum, Secale sylvestre, as well as an endemic Balkan taxon Astragalus onobrychis subsp. scorpili. Species such Arenaria serpilifolia, Cladonia foliacea, Poa bulbosa and Syntrichia ruralis typify the northern, shady, humid dune slopes, but where there is some loose sand, on steep sunny slopes and in some flatter areas, species such as Cionura erecta, Festuca vaginata, Galilea mucronata, Peucedanum arenarium and Silene euxina predominate. Other taxa include Alyssum hirsutum subsp. caespitosum, Alyssum minutum, Amorpha fruticosa, Anchusa leptophylla, Carex ligerica, Cerastium semidecandrum, Chondrilla juncea, Chrysopogon gryllus, Echium vulgare, Elymus pycnanthus, Erianthus ravennae, Erysimum diffusum, Festuca vaginata, Galilea mucronata, Jasione heldreichii, Kochia laniflora, Linaria genistifolia subsp. genistifolia, Medicago falcata subsp. tenderiensis, Melilotus alba, Morus alba, Orobanche arenaria, Osyris alba, Pancratium maritimum, Papaver hybridum, Peucedanum arenarium, Phleum graecum, Rumex tenuifolis, Scabiosa argentea, Silene euxina, Teucrium polium subsp. vincentinum, Trachomytum venetum, Vitis vinifera, Xanthium italicum and Xanthoria parietina.

Carex ligerica - Stachys atherocalyx Association
This association occurs in different dune systems along the entire Bulgarian coast but most of them are northwards from Kamchiiski dunes. Carex ligerica is often the dominant species especially in the flatter areas where sand is more compacted and humid. Stachys atherocalyx is also frequently encountered with a range extending from the Balkan Peninsula to the Ukrainian and Crimean Black sea coast. Other common species are Centaurea arenaria subsp. borysthenica, Linaria genistifolia subsp. genistifolia, Chondrilla juncea and Jasione heldreichii. Other taxa include Allium guttatum, Althaea officinalis, Alyssum minutum, Ammophila arenaria, Anchusa leptophylla, Artemisia campestris, Astragalus onobrychis subsp. scorpili, Aurinia uechtritziana, Clematis vitalba, Conyza canadensis, Crepis foetida subsp. foetida, Dianthus moesiacus subsp. moesiacus, Eryngium maritimum, Erysimum diffusum, Festuca vaginata, Holoschoenus vulgaris, Leymus racemosus, Linaria genistifolia, Linum tauricum subsp. bulgaricum, Medicago falcata subsp. tenderiensis, Peucedanum arenarium, Poa pratensis, Silene conica subsp. conomaritima, Teucrium polium subsp. vincentinum, Trifolium arvense,Verbascum purpureum and Verbena officinalis.

Ephedra distacha - Alyssum borzaeanum Association
This association tends to occur on the inner parts of the fixed dunes and has a very distinctive species composition. The presence of Balkan endemic Verbascum purpureum and the xerothermic species Syntrichia ruralis emphasizes this distinctiveness. However, the association also includes signs of ruderalisation with various anthropophytes and ruderals such as Echium vulgare, Marrubium peregrinum and Prunus spinosa. Other taxa include Ammophila arenaria, Aristolochia clematitis, Astragalus onobrychis subsp. scorpili, Centaurea arenaria, Cynanchum acutum, Eryngium campestre, Erysimum diffusum, Euphorbia seguierana, Festuca vaginata, Medicago falcata subsp. tenderiensis, Melica ciliata, Scabiosa argentea, Silene thymifolia, Syntrichia ruralis and Xanthoria parietina.

Euxine Dunes Igneada Coast Turkey (Kavgaci 2007)

The Igneada region is sutuated in the northwest Thracian part part of Turkey and regarded as one of the most important plant areas in Turkey, and the sand dune vegetation is an imporant ecological component of the area.

Two dune communities have been defined. These include a seaward fringe community characterised by Leymus racemosus subsp. sabulosus and Otanthus maritimus, a mid-dune community characterised by Cionura erecta and Medicago rigidula, and a hinterland meadow zone supporting a complex assemblage of species.

Leymus racemosus subsp. sabulosus - Otanthus maritimus Community
This pioneer community forms in a relative flat area with a few small hillocks just above high tide, but the area is relatively unstable. Associated species include Cionura erecta, Eryngium maritimum, Hypochaeris radicata, Lolium rigidum, Maresia nana, Secale sylvestre, Silene dichotoma, Stachys annua together with the endemic species Centaurea kilaea and Silene sangaria. However there is evidence of human usage and overgrazing in places.

Cionura erecta and Medicago rigidula Community
Some distance from the sea this community forms the next zone of vegetation where more stable conditions prevail. The topography is again relatively flat with just a few small hillocks and hollows. Associated species include Cerastium pumilum, Cionura erecta, Medicago rigidula, Muscari neglectum and Teucrium polium.

Dune Meadow Zone
This inner part of the sand dune supports a complex mixture of species. It includes, for example, indicators of disturbance, such as Cynodon dactylon and Rumex pulcher and species characteristic of fine soils such as Oenanthe fistulosa and Parentucellia latifolia. However, Arenaria serpyllifolia, Leontodon tuberosus and Parentucellia latifolia are the dominant species, while other associated species are Eryngium campestre, Petrorhagia velutina, Poa bulbosa, Trifolium campestre and Vulpia ciliata.

 

References

Hanganu, J., Grigoras, I., Stefen, Sarbu, I., N., Dubyna, D., Zhmud, E., Menke, U. & Drost, H. 2002. Vegetation of the Biosphere Reserve “Danube Delta”. Ministry of Waters and Environmental Protection, Romania. National Acadamy of Sciences of Ukraine, Directorate-General for Public Works and Water Management, The Netherlands.

Kavgaci, A. 2007.  Sand-dune vegetation of Igneada coast in the Thracian part of Turkey. Hacqutia, 6: 171-182.

Tzonev, R., Dimitrov, M. and V. Roussakova 2005. Dune vegetation of Bulgarian Black Sea coast. Hacquetia, 4: 7-32