Desislava Sopotlieva

The Balkan wet grassland vegetation: a prerequisite to better understanding of European habitat diversity

The knowledge of broad-scale floristic variation in wet grasslands, which are endangered throughout Europe, is still limited and some regions have remained unexplored so far. In addition, hitherto published phytosociological studies were concentrated at the national level and therefore national vegetation classifications are not consistent with each other. In order to overcome these shortcomings of traditional phytosociology, we gathered original data from Bulgaria and analysed them together with the data from Central Europe. We further analysed major compositional gradients within Bulgarian wet grasslands and changes in species richness along them. We sampled 164 wet grassland vegetation plots throughout Bulgaria. We further prepared a restricted data set of wet grasslands from Central-European phytosociological databases. Both data sets were merged and classified by modified TWINSPAN. Four distinct vegetation types were differentiated. Even if they correspond with traditional alliances, which are primarily drawn as geographically defined units in Western and Central Europe (sub-Mediterranean Trifolion resupinati, sub-continental Deschampsion cespitosae and Molinion caeruleae and sub-oceanic Calthion palustris), they all occur in Bulgaria. When more precise classification was applied, two types of sub-Mediterranean wet grasslands and one high-altitude type of Calthion grasslands were detected solely in Bulgaria. DCA analysis showed that altitude is a dominant gradient controlling variation in Balkan wet grasslands. The second DCA axis was interpreted as the gradient of nutrient availability. Species richness shows skewed-unimodal trends along both major gradients, with the highest species richness in intermittently wet nutrient-limited grasslands. Tukey post-hoc test of altitudinal differences amongst vegetation types is significant for all pairs of clusters, suggesting that altitudinal differentiation is responsible for co-occurrence of nearly all European types of wet grasslands in Bulgaria. Our results suggest that (1) climate is an important factor for the diversity of wet grasslands; (2) Balkan vegetation of middle altitudes matches with that of Central Europe, whereas that of the lowest altitudes corresponds rather to the sub-Mediterranean region and high mountains are specific; (3) upward shift of Central-European vegetation types in southern Europe, so often described in forest vegetation is also evident for grassland vegetation and (4) the high diversity of Balkan vegetation is determined by a diverse relief enabling confluence of habitats possessing different climatic conditions.

The Association Erysimo - Trifolietum Micev. 1977 in Bulgaria and Some Remarks on its Mediterranean Character

The Association Erysimo - Trifolietum Micev. 1977 in Bulgaria and Some Remarks on its Mediterranean Character We endeavor to enlarge the knowledge about Bulgarian vegetation diversity. Data on seminatural grasslands containing 344 relevés, collected in Southeast Bulgaria were analyzed by the combine method, using TWIN-SPAN and the Cocktail method. The Erysimo diffusii-Trifolietum angustifolii association and the alliance Trifolion cherleri were established for the first time in Bulgaria. So far the presence of this association was known for Macedonia. The aims of our study are to present more data about the Erysimo-Trifolietum in Bulgaria and to make some comments about its affiliation to Helianthemetea guttati. The association is characterized ecologically and floristically. Analysis of the floristic elements shows that the most numerous are sub-Mediterranean species. Analysis of the life forms shows that these communities are hemicryptophyte-therophytic. A review of syntaxonomical systems and association assignment to higher syntaxa were made. According to current European vege-tation surveys the association should be related to class Helianthemetea guttati. Our results reveal an intermediate character of the studied vegetation - closed dry grasslands, with distinct presence of Festuco-Brometea species with a high percent of therophytes and Mediterranean floristic elements related to Helianthemetea guttati as well. Članek je prispevek k poznavanju raznovrstnosti vegetacije Bolgarije. Podatke, ki obsegajo 344 popisov, nare-jenih v jugovzhodni Bolgariji, smo analizirali s kombinacijo metod TWINSPAN in Cocktail. Asociacija Erysimo diffusii-Trifolietum angustifolii in zveza Trifolion cherleri sta prvič omenjeni v vegetaciji Bolgarije. Do sedaj je bila prisotnost te asociacije poznana le v Makedoniji. Namen raziskave je predstaviti dodatne podatke o asociaciji Erysimo-Trifolietum v Bolgariji in podati nekaj komentarjev o njeni uvrstitvi v razred Helianthemetea guttati. Asociacija je označena ekološko in floristično. Analiza flornih elementov je pokazala, da so submediteranske vrste najštevilnejše. Analiza življenjskih oblik pa, da je to hemikriptofitsko-terofitska združba. Opravljen je pregled sinataksonomskega sistema in uvrstitev v višje sintaksone. Po trenutnem pregledu evropske vegetacije jo uvrščamo v razred Helianthemetea guttati. Naši rezultati pa razkrivajo vmesni značaj obravnavane vegetacije - sorodnost s suhimi travniki s prisotnostjo vrst Festuco-Brometea in visokim odstotkom terofitov in z razredom Helianthemetea guttati, ki ga označujejo mediteranski elementi.

The insecure future of Bulgarian refugial mires: economic progress versus Natura 2000

Bulgarian mires acted as refugia during the dry phases of ice ages and contain a high number of rare and disjunct species. In this study we ranked all known mire and spring complexes in Bulgaria according to the occurrence of rare and threatened plant and mollusc species. This analysis shows a conspicuous concentration of rare species at several sites, and no correspondence between the importance of individual mires for biodiversity and their legal protection. Of the 10 mire complexes of highest priority only one is effectively protected. The remaining unprotected mires have either been destroyed or are threatened by ongoing development. Destruction of mire habitats proceeds faster than the approval of Natura 2000 sites. There is a possibility that unique Bulgarian mires will be lost before the Natura 2000 system begins to perform its role. Only effective and timely protection of the mire remnants, together with appropriate management, will ensure the future of these unique habitats.

Is penetration of non-psammophytes an underestimated threat to sand dunes? - a case study from western Pontic coast

The aim of this study was to identify how far the different dune types from one of the largest dune complexes at the Bulgarian Black Sea Coast are affected by the penetration of non-psammophytes and if there is an upward trend in their number. We studied the Kamchia dune system during 2013–2015. Vegetation was sampled at 162 plots along 12 transects systematically situated to cover three different habitats: embryonic, white and grey dunes. All vascular plants as well as cover percentage of each species and total vegetation cover were registered within each plot. The overall species list of the different dune types was additionally completed for the whole study area. A total 207 plant species were registered. They were classified into five groups as follows: psammophytes – 38, weeds and ruderals – 36, plants typical of grasslands and shrublands – 95, plants typical of forests – 18 and alien (including invasive) species – 20. Number and cover of defined groups were calculated in respect to their distribution in different dune habitats. Results show that grey dunes contain the highest percentage of non-psammophytic plants, which decrease towards white and embryonic dunes. The studied coastal area is still less influenced by non-psammophytes. It represents an example of a Bulgarian Black Sea coastal dune complex that is relatively unaffected by urbanization. The high floristic and habitat diversity deserve further effective protection.