engleski

The vegetation of the Ston saltern (Southern Adriatic, Croatia)

The saltern in the town of Ston is the oldest in Europe, dating back to the 14th century. The saltern did not change its appearance and mode of production since the foundation. The territory of the saltern (the production area of ca. 43 ha) is structurally composed of areas having various configurations in relation to the different production phases of salt: the storage basins and the first evaporation ponds present irregular morphologies and reveal their membership in the biotope from which they originate, while the second and third evaporation ponds, the salting basins and the canal system correspond to man-made structures having a very regular morphology. Several phytosociological papers have already dealt with the vegetation of the salterns in the Adriatic Basin, however, the saltern in Ston remains site that has not yet been investigated. In 2018 and 2019, soil and water properties, water level, plant distribution and succession at salt pans were studied. Altogether, 52 phytosociological relevés were carried out following the Braun- Blanquet method (Whestoff and van der Maarel, 1978). The water salinity was affected by seawater input, rainfall and evaporation. From October to April, seawater was introduced for salt production. The pH of salt pan soils was mostly above 8. Soil salinity was particularly high (more than 400) at crystallizing ponds. In rainy season, the brine was somewhat diluted. The main ecological factors which determine the various distributions of the vegetational types are the level and salinity of the water. There are only 21 halophytic taxa at the salt pans under operation (9) where soil and water salinity are extremely high. Two type of vegetation were determined: halophytic and halotolerant. The associations of the Phragmito- Magnocaricetea Klika in Klika et Novák 1941, Ruppietea maritimae J. Tx. ex Den Hartog et Segal 1964, Therosalicornietea Tx. in Tx. et Oberd. 1958, Juncetea maritimi Br.-Bl. in Br.-Bl. et al. 1952, Salicornietea fruticosae Br.-Bl. et Tx. ex A. Bolòs y Vayreda et O. de Bolòs in A. Bolòs y Vayreda 1950 and Cystoseiretea Giaccone 1965 classes were identified. The result confirmed "azonal vegetation" character of the halophilic populations, i.e. their widespread geographic distribution, but strictly linked to very particular edaphic conditions which thus assume the role of ecologic factors, absolutely prevalent and determinant. Major efforts should be addressed to further research of the biodiversity of the area and for a design of the most efficient conservation strategy.

ecology ; gradient ; halophilous vegetation ; numerical analysis ; phytosociology

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