18E3
Danubian riverside flooded meadows
Relationships with habitat classifications. EUNIS: E3.43 Subcontinental riverine meadows; PAL. CLASS.: 37.23 Subcontinental riverine meadows; HD 92/43: 6440 Alluvial meadows of river valleys of the Cnidion dubii.
Conservation status. BDA, BC, HD.
Category. Critically endangered [CR - A1, 2 B1 C2 D3 E3 F3 G3 H2 I J].
General characteristics. This habitat type is very close to the lowland hay meadows and can be regarded as their Danubian variety. Typically for Danubian riverine flooded meadows is that they develop in continental climate conditions and at irregular flooding periods from the Danube with different prolongation. The flooding is most often in April, and when the water subsides in May-June, meadows rich in species composition develop. These meadows used to be widely distributed along the Danube in the past and formed the transitional zone between the typical hygrophytic and hydrophytic vegetation on the one hand and mesoxerothermic and xerothermic coenoses and riverside forests on the other. The redirection of the river bed and and draining of the swamps have caused almost the complete disappearance of these meadows. Very small fragments remain in places with high humidity that are sporadically flooded by the neighbouring drainage canals or high underground waters, e.g. fish farms, and pump stations. These fragments are strongly ruderalized and with changed species composition, hence one cannot have a clear idea of the primary composition of the riverine meadows along the Danube. Small fragments of this habitat type have been registered in Bregovo-Novo Selo lowland (this is the only place where dykes have not been built on the Danube); Archar lowland, Svistov-Belene lowland, and the vicinities of the former Brashlen swamps that has been transformed into a reed marsh. The species composition depends on the humidity and can include both mesophytes and typical hygrophytes. To the first group most often belong: Agrostis stolonifera, Allium angulosum, Alopecurus pratensis, Althaea officinalis, Clematis integrifolia, Elymus repens, Euphorbia lucida, Festuca pratensis, Lycopus exaltatus, Lythrum virgatum, Poa palustris, Ranunculus acris, Teucrium scordium, Thalictrum flavum, T. lucidum, and to the second group: Alisma plantago-aquatica, Butomus umbellatus, Carex melanostachya, C. praecox, Gratiola officinalis, Eleocharis palustris, Leucojum aestivum, Phalaris arundinacea, Scirpus lacustris (= Schoenoplectus lacustris), Scutellaria hastifolia, Symphytum officinale.When the salinity of the soil and ruderalization (most often as a result of nitrification and pollution due to grazing) increase, the number of different ruderals and semi-ruderals, some of which halophytes, also increases: Cynodon dactylon, Juncus gerardii, Mentha pulegium, Trifolium fragiferum subsp. bonannii, and Xanthium strumarium.
Characteristic taxa.
- Vascular plants: Agrostis stolonifera, Alisma plantago-aquatica, Allium angulosum, Alopecurus pratensis, Althaea officinalis, Butomus umbellatus, Carex melanostachya, C. praecox, Clematis integrifolia, Elymus repens, Euphorbia lucida, Festuca pratensis, Galium album, G. palustre, Gratiola officinalis, Eleocharis palustris, Inula britannica, Leucojum aestivum, Lycopus exaltatus, Lysimachia nummularia, Lythrum virgatum, Mentha pulegium, Phalaris arundinacea, Poa palustris, Potentilla reptans, Ranunculus acris, Scirpus lacustris, Scutellaria galericulata, S. hastifolia, Symphytum officinale, Teucrium scordium, Thalictrum flavum, T. lucidum, Trifolium fragiferum subsp. bonannii, T. resupinatum, Xanthium strumarium.
- Fungi: Macromycetes – Agaricus spp., Bovista plumbea, Marasmius oreades; Micromycetes – Anthracoidea arenaria (on Carex praecox), Blumeria graminis, Ustilago striiformis (on Alopecurus pratensis), Golovinomyces cynoglossi, Melampsorella symphyti, Peronospora symphyti (on Symphytum officinale), Puccinia coronata, P. graminis (on Festuca pratensis), Puccinia poarum (on Poa palustris), Uromyces dactylidis (on Ranunculus acris).
- Animals: Mammalia – Nyctalus noctula, Pipistrellus nathusii, P. pipistrellus.
Distribution in Bulgaria. Danubian plain (the flooded lowlands along the Danube), Bregovo-Novo Selo, Archar, Svistov-Belene and Brashlen lowlands; in the past also at the estuary of Osam river and in other places.
Conservation importance. The habitat in Bulgaria is very rare and with very restricted area of distribution. Rare, endangered, protected and valuable medicinal plants grow in these meadows: Allium angulosum, Althaea officinalis, Armoracia macrocarpa, Leucojum aestivum.
Threats. The main reasons for the disappearance of this habitat type was the hydro-ameliorative activities along the Danube in Bulgaria: construction of dykes and draining of the large swamps. The riverine meadows used to be cultivated in the past and were transformed into saline pastures as a result of overgrazing. Negative impacts are also the general aridisation, development of poplar plantations, draining of the riverside lowlands, soil pollution and the consequent ruderalization, etc.
Conservation measures taken. The habitat is included in Annex № 1 of the national Biodiversity Act. Most of the localities are within protected areas – Persina Nature Park, Kalimok-Brashlen Protected Site and sites of the European Ecological Network NATURA 2000 in Bulgaria.
Conservation measures needed. Mapping and monitoring of the existing fragments of the riverine flooded meadows along the Danube; restoration of some of them, especially the ones that have low productivity and high underground waters; restriction of grazing, reintroduction of some of the most typical species for this habitat type such as Leucojum aestivum and Allium angulosum (a critically endangered species that has disappeared from most of its known localities).
References. Ganchev et al. 1964; Stojanov 1948.
Authors:. Rossen Tzonev, Chavdar Gussev
