13E1
Danubian sand dunes and inland dunes (gredove) from sandy loess
Relationships with habitat classifications. EUNIS: E1.9B Pannonic inland dunes; PAL. CLASS.: 64.71 Pannonic inland dunes; HD 92/43: 2340 *Pannonic inland dunes.
Conservation status. BDA, BC, HD.
Category. Critically endangered [CR – A1, 2 B1 C3 D3 E3 F1 G2 H3 I L2].
General characteristics. This habitat comprises inland continental dunes (called “gredove”) on sandy loess and alluvial sediments, distributed only in the flooded lowlands along the Danube. The largest areas covered by this habitat are located in Bregovo-Novo Selo, Orsoya, Tsibar, Ostrov and Chernopol (Karaboaz) lowlands. These “gredove” are of mixed, alluvial and eolic origin, and are of different size. Usually, they are several tens of meters long and about ten meters wide. The altitude varies – the alluvial ones are up to 2 m above the flooding level of the Danube. Before the dikes along the river were constructed they were flooded only only when the water level of the Danube was very high. The loess, sandy “gredove” are higher, up to 5–6 m. Often a complex of communities develop on these dunes: mosses on open sands, communities of terrophytes including many ruderals, open and closed xerothermic, perennial herbaceous communities. Typical for most of these communities is the high degree of xerophytisation as a result of anthropogenic activities. Some of the dunes, e.g. in Ostrov and Karaboaz lowlands, have been ploughed and cultivated in the past but currently these activities have stopped. As a result of this, the vegetation is very much destroyed. On Persina Island (Belene) low dunes (“gredi”) divide the big marshes on the island. Cattle have grazed there for decades hence causing a high level of degradation. The coenoses of the association Tribulo-Tragetum occurs on the “gredi” in Persina island. They include many ruderals - terrophytes. The most frequent dominants in the destroyed (ruderalized) plant communities on the dunes are Artemisia scoparia, Bromus tectorum, Chondrilla juncea, Conyza canadensis, Cynodon dactylon, Eragrostis minor, Euphorbia chamaesice, Plantago lanceolata var. eriophylla, P. scabra, Portulaca oleracea, Salsola ruthenica, Tragus racemosus, and Tribulus terrestris.Representatives of the autochthonous flora have been preserved in some places, such as Centaurea arenaria (Karaboaz, Orsoya, Tsibar), Allium angulosum (Persina Island), Tragopogon floccosus. The dunes in Orsoya lowland are well preserved although there, as well as in Tsibar lowland, there are many sand-pits. Pioneer coenoses with Alkanna tinctoria are typical for the open, mobile sands. More closed communities occur on these dunes where, together with the species mentioned above Apera spica-venti, Elymus repens, Scabiosa argentea, Seseli tortuosum, etc. also occur. Moss coenoses develop on the more open sands with Syntrychia ruralis, Bryum argenteum, etc. Communities of Kochia prostrata develop on the loess, sandy “gredi” and swaths. Ruderalized xerothermic pastures of Bothriochloa ischaemum(= Dichanthium ischaemum) occur on some of the drier ridge areas of the “gredi” (e.g. Belene lowland).
Characteristic taxa.
- Vascular plants: Alkanna tinctoria, Allium angulosum, Apera spica-venti, Artemisia scoparia, Bothriochloa ischaemum (= Dichanthium ischaemum), Bromus tectorum, Centaurea arenaria, Crepis setosa, Cynodon dactylon, Elymus repens, Eragrostis minor, Euphorbia chamaesice, Kochia prostrata, Matricaria trichophylla, Petrorhagia prolifera, Plantago lanceolata var. eriophylla, P. scabra, Portulaca oleracea, Salsola ruthenica, Scabiosa argentea, Seseli tortuosum, Silene conica,Tragopogon floccosus, Tragus racemosus, Tribulus terrestris, Trifolium arvense, Verbascum banaticum, Xeranthemum annuum; mosses – Bryum argenteum, Syntrichia ruralis.
- Fungi: Macromycetes – Agaricus bernardii, Battarrea phalloides, Crinipellis scabella, Geastrum spp., Panaeolina foenisecii, Panaeolus papilionaceus, Phallus hadrianii, Psathyrella ammophyla, Stropharia coronilla;Micromycetes – Puccinia cesatii (on Dichanthium ischaemum), P. coronata (on Bromus tectorum and Cynodon dactylon), P. cynodontis, P. graminis, Ustilago cynodontis (on Cynodon dactylon), P. stipae (on Stipa capillata).
- Animals: Invertebrates – Acrida spp.,Vertebrates: Pelobates fuscus, P. syriacus, Coracias garrulus, Merops apiaster.
Distribution in Bulgaria. Lowlands along the Danube: Bregovo-Novo Selo, Orsoya, Tsibar, Ostrov and Chernopol (Karaboaz), Svistov-Belene (including Belene Island), Vardim lowlands.
Conservation importance. This habitat covers a very small area in Bulgaria. Some rare and protected species with single localities occur inland: Centaurea arenaria, Allium angulosum, Tragopogon floccosus (endemic for the Danube water catchment). Also some fungi of conservation importance occur: Battarrea phalloides, Phallus hadrianii.
Threats. Mainly urbanization, agricultural activities and illegal extraction of sand. Most of these dunes have been ploughed and cultivated hence the occurrence of many ruderals and alien species. Their destruction as a result of sand extraction is irreversible. Such activities have been registered in Orsoya, Tsibar, Ostrov and Chernopol (Karaboaz) lowlands. In Persina island some of the dunes have been overgrown by the invasive species Amorpha fruticosa.
Conservation measures taken. The species is included in Annex № 1 of the national Biodiversity Act and is of conservation priority. Part of this habitat is protected within Persina Nature Park. Some localities are in sites of the European Ecological Network NATURA 2000 in Bulgaria (Orsoya, Tsibar, Ostrov and Chernopol (Karaboaz) lowlands).
Conservation measures needed. Monitoring of the habitat state and proclamation of protected zones and sites in the areas where this habitat occurs; termination of illegal sand extraction.
References. Tzonev 2009.
Author: Rossen Tzonev
