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The Bartsia trixaginis-Scirpoidetum holoschoeni association in Catalonia The coastal fixed sands grassland of Bartsia trixaginis-Scirpoidetum holoschoeni O. Bolòs 1962, comprises a community of great ecological interest due to its unique character. Up to now, its known distribution in Catalonia has been limited to the county of Baix Llobregat, where Bolòs (1962) described the association on the basis of a single inventory made in 1950. In the course of a dune vegetation study conducted in the province of Girona, new localities for this association were identified in the Alt Empordà and Baix Empordà counties, bringing the total number of localities to six. This paper presents 12 unpublished inventories that have enabled us to analyse the community from phytosociological and ecological perspectives. These backdune meadows are very limited in both distribution and extent, due to habitat destruction and the loss of natural dynamics. The variability of the association allows us to distinguish up to three new ecological varieties , always marked by the presence of Thero-Brachypodietea species. The community is ephemeral, in transition between Ammophilion arundinaceae dune units and Mediterranean vegetation, and is of great conservation interest as well as being highly threatened. Based on the observations and inventories made, this paper highlights the importance of these meadows and the need to increase our knowledge of them, in order to preserve them within a profoundly transformed coastline.
The small islands in the Mediterranean basin play an important role in its diversity because they have very unique natural habitats. They are very vulnerable to the direct and indirect effects of human activity, which severely impact ecosystems. Our study analysed the dynamics of the vegetation over recent years on one small island in an attempt to understand how the vegetation is changing and whether this is impacting the habitat diversity. The study was conducted on the Meda Gran, the largest island in the Medes Islands archipelago, which is located to the northeast of the Iberian Peninsula. A diachronic analysis was performed using the current vegetation cartography and a map published in 1984. Two dynamics were identified: the ruderalization caused by the overpopulated seagull colony and the natural succession of the vegetation. These processes have led to a loss of habitats on the island, such as the Astragalus tragacantha habitat, or on the contrary, the growth of populations of invasive species such as Opuntia ficus-indica. These patterns highlight the vulnerability of these small islands and the need for effective management to conserve these protected natural areas and their habitats.