The Conservation Value of Temporary Ponds in the Ciuc Basin (Transylvania, Romania) from a Vegetation Perspective

Anna-Mária CSERGŐ 1and László DEMETER 2

1 Sapientia University, Sighisoarei Str. 1C, Corunca, Romania,
2 Sapientia University, Libertatii Str. 1, Miercurea-Ciuc, Romania,

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phytosociological relevés, eutrophic ponds, oligotrophic ponds, pond zones, hydroperiod, alluvial fans, Natura 2000 habitats, protected species, glacial relicts.


In the past years we have mapped a large number of characteristic ponds on the alluvial fans of the Ciuc Basin in Romania, which were not studied previously. In this study we present the results of a survey conducted on the vegetation of these ponds. We revealed a large number of protected species and plant communities of high conservation value.

Although the Ciuc Basin is well known for the large number of glacial relic plants, our study documents that they are locally more frequent than previously thought.


Temporary ponds are vulnerable, though long-neglected habitats in Romania (Bănărescu 1970, Bănărescu 1995). Within the Ciuc Basin, mostly known for its alkaline fens and spring fens, botanists did not pay attention to this peculiar habitat type. There is only a single preliminary report on plant diversity of these habitats (Demeter et al., 2005).

A large number of temporary ponds are scattered among hay meadows in the Ciuc Basin, and thus bring an important contribution to their biodiversity. Some of them are even mown in the dry phase.

The aim of the present study was to assess the vegetation of the temporary ponds in the Ciuc Basin (Eastern Transylvania, Romania) (Fig. 1). We highlight the conservation value of this habitat in the Ciuc Basin in general and in different localities in particular, from the perspective of the vulnerable plant communities and of the protected plant species. We also note the most important human interferences with the ponds and their impact on vegetation characteristics.

During 2006-2009, we studied the vegetation of 45 temporary ponds (of a total of more than 250) in eight localities of the Ciuc Basin (Delniţa, Ciceu, Ciaracio, Ciba, Racu, Miercurea-Ciuc, Sântimbru, Sânsimion). We assessed all plant communities of each studied pond regardless of their proportion in the pond, by taking phystosociological relevés. The assignment to different associations was based on the presence of characteristic species, according to the Central European School, using Coldea (1991) and Sanda et al. (2008).

Figure 1: Location of study area (Ciuc Basin, Eastern Transylvania, Romania)


We registered 128 phytosociological relevés, 28 plant communities and more than 200 plant species. Rare or protected species which occured in immediate pond surroundings were also included.

In the temporary ponds of Ciuc Basin, swamp- and tall-herb fen communities were the most common ones, because they are best adapted to fluctuating water level and drier periods. Such communities were Typhetum latifoliae Lang 1973, Caricetum gracilis (Graebn. et Hueck 1931) Tüxen 1937, Caricetum vesicariae Br.-Bl. et Denis 1926, Caricetum cespitosae (Steffen 1931) Klika et Smaranda 1940, and Caricetum elatae Koch 1926. They indicate eu-mesotrophic, alkaline ponds or pond zones, rich in organic matter.

A series of other plant communities were sparse, such as: Caricetum acutiformis Eggler 1933; Calamagrostetum canescentis Podbielowski 1970;  Calamagrostetum epigei Juraszek 1928;  Callitrichetum cophocarpae Pócs (1958)1998; Caricetum distichae Nowinski 1927;  Caricetum vulpinae Novinski 1927;  Equisetetum fluviatilis Steffen 1931;  Glycerietum maximae Hueck 1931;  Juncetum effusi Soó (1931)1949; Juncetum conglomerati Prodan 1939; Scirpo-Phragmitetum Koch 1926; Calamagrostio-Salicetum cinereae Soó et Zólyomi in Soó 1955; Scirpetum sylvatici Ralski 1931, Maloch 1935 em. Schwick 1944;  Caricetum rostratae Rübel 1912; Sparganietum erecti Roll 1938.

Other communities were more rare, such as  Sphagno-Caricetum curtae Pass. 1964; Caricetum lasiocarpae Koch 1926; Sphagno-Caricetum rostratae Steffen 1931; Carici echinatae-Sphagnetum Soó (1934) 1954. They developed in peaty, acidic or neutral ponds or pond zones. As they require a more stable hydroperiod, they are more vulnerable and therefore important from conservational point of view. Most of them belong to the „7140 - Transition mires and quaking bogs” habitat type of the Habitat Directive. We have found them in Ciaracio, Ciba, Racu, Miercurea-Ciuc, Sânsimion localities. We believe that the trophicity level is strongly influenced by the size and hydroperiod of ponds, and also the history of pond use by local people. Most likely, the meso-oligotrophic ponds have changed to eutrophic ones, because of alterations in their hydroperiod in the past.

Other rare plant communities were Carici flavae-Eriophoretum latifolii Soó 1944 and Junco-Molinietum Preising 1951 ex Klapp 1954, which developed at pond margins.

Several ponds sheltered glacial relic or nationally protected plant species. So far, 14 such species were recorded and 29 out of the 49 ponds had at least one protected species (Fig. 2). Of great significance is the presence of Lysimachia thyrsiflora, Utricularia vulgaris, Comarum palustre and Spiraea salicifolia, which are frequent, and have large and stable populations. Lysimachia thyrsiflora was previously known in the Ciuc Basin only from Tuşnad, Sânsimion, Vrabia, Ciceu-Topliţa, Sâncrăieni and Miercurea-Ciuc, whereas Utricularia vulgaris only from Sânsimion (see Soó 1940, Soó 1943, Oprea 2005 and references therein). Lemno-Utricularietum vulgaris Soó 1928, a rare community of the ponds, was found as such in Ciceu and Racu, although Utricularia vulgaris was commonly registered in deeper ponds. Spiraea salicifolia grew mostly in the drier, marginal parts of the ponds. Ribes nigrum, Carex diandra, Cicuta virosa, Eriophorum vaginatum, Salix pentandra, Salix aurita, Dactylorhiza incarnata, Dianthus superbus, and Iris sibirica were very rare, each found in only one pond. Menyanthetum trifoliatae Steffen 1931 community, found in three ponds, is of high conservation value. It was found in a bushy pond, the edge of a bog-pond and in a pond that has a deep ditch in the middle, as a result of a drainage attempt. Carex diandra was previously known only from Sâncrăieni, Tuşnad-Sat, Tuşnadu Nou and Jigodin, whereas Eriophorum vaginatum was not mentioned in the Ciuc Basin before (Soó 1940). Rare species presence and distribution in a pond is likely to depend on factors such as water depth, vegetation type and shading, water pH, etc.

Unfortunately, some ponds were filled up totally or partially with sawdust or were drained. This had a strong negative impact on the floristic composition of the plant communities, as meadow- or weed species invaded them, or in the worst cases, ponds became „sawdust deserts”. Superficial burning of dry vegetation is commonly practiced in the area. During this study we could not identify a negative effect of this activity. Deep burning probably has a stronger negative impact on the vegetation of ponds with a peaty substrate, as following peat decomposition, characteristic mezo-oligotrophic communities may lose specificity and eutrophic communities may take over. It seems that mowing has no negative effect on vegetation, on the contrary, it is likely to have increased species diversity at pond margins. In one case, the presence of Menyanthes trifoliata is clearly related to a drainage ditch that increased the water depth of a pond. Yet, the available data do not allow us to quantify the effect of these processes and therefore the anthropogenic impact on vegetation within ponds of Ciuc Basin needs further detailed studies.

Figure 2: Distribution map of the nationally protected and glacial relic plant species within the inventoried temporary ponds in eight localities of the Ciuc Basin (Eastern Transylvania, Romania).


This paper presents for the first time a comprehensive checklist of the plant communities of the temporary ponds in Ciuc Basin. From a plant community perspective, ponds with vulnerable, peatmoss-dominated oligotrophic vegetation are the most important to conservation. They are  scattered along Ciaracio, Ciba, Racu, Miercurea-Ciuc, Sânsimion, but do not represent exclusively these localities. Oligotrophic conditions are seemingly related to the specific and strictly local ecological conditions of each pond.

In turn, glacial relict and nationally protected plant species grow in ponds of both eutrophic and oligotrophic character. From this perspective, all ponds are potential shelters of protected plant species and need to be protected.

The temporary ponds of Ciuc Basin need further botanical research. Being extremely sensitive to human impact, they require much attention and legal protection.


The authors thank Barbara Knowles and the Sapientia Institute for Research Programmes who financed this study.


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