Аннотация:Calcareous fens are unique environments whose history is almost unexplored. The radiocarbon dates of the basal layers of 49 undisturbed calcareous fens showed that in the W estern C arpathians (central E urope) many of the extant fen sites originated fairly recently, with two peaks in the H igh M iddle and R oman A ges, the former corresponding to human‐induced changes of the landscape. Conspicuous number of fens also appeared in the L ateglacial and later in the B ronze A ge owing to suitable environmental conditions. The L ateglacial calcareous fens were of semi‐open character with coniferous trees, a heliophilous understorey, and mollusc communities composed of several snail species typical of glacial landscapes. We found wood of T axus baccata in six localities between 7390 and 600 cal. a BP , suggesting that calcareous fens could have represented a refugial habitat for this red‐listed species during the middle H olocene. Using plant macrofossil and mollusc analyses of three representative profiles we illustrate the most common developmental types: (i) fens originating in the L ateglacial, having an open or semi‐open character during the whole Holocene; (ii) open fens originating as wooded wetlands; and (iii) open fens starting their development de novo in the late Holocene. Human activities were responsible for the formation of a high number of calcareous fens, especially in the O uter W estern C arpathians, and became important drivers of fen biodiversity development. Only a few recently existing calcareous fens contain old sequences of calcareous deposits. They represent unique natural archives and harbour highly endangered relic populations of fen specialists, making their strict protection urgent.
