1. Die Stranddistel, Eryngium maritimum, in Niedersachsen (Deutschland).
- Author
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Isermann, Maike, Oltmanns, Bernd, Biewer, Niels, Bremenkamp, Meike, Gent, Onno K., Gerlach, Frauke, Großewinkelmann, Markus, Heckroth, Mathias, Keller, Sebastian, Kramer, André, Müller, Anette, Penner, Frank, Potthast, Simon, Riechmann, Christopher, Runar, Jochen, Scheller, Lars, Schulze, Karla, and Südbeck, Peter
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SAND dunes , *MOBILE geographic information systems , *ENDANGERED plants , *BODIES of water , *NATURE conservation , *GRID cells - Abstract
In Germany, including Lower Saxony, Eryngium maritimum (Sea Holly) is a highly endangered plant species protected by law. The species is known mainly from shifting dunes with Ammophila arenaria (EU habitat type 2120) and from younger calcareous soils of fixed coastal dunes with herbaceous vegetation (EU habitat type 2130). Eryngium maritimum was reported from all the large East Frisian Islands before 1900. The aim of this study was to re-map the distribution of this species along the coast of Lower Saxony, particularly in the Lower Saxon Wadden Sea National Park, and to record the habitats in which it occurs. Methods: E. maritimum was mapped with a mobile App-based geographic information system by rangers and other staff of the National Park Authority in 2020. On Spiekeroog, due to the large number of individual plants, mapping started in 2018, In addition, in 2022 some areas on the mainland not originally foreseen (i.e. Wangerland, Cuxhaven) were surveyed. The number of vegetative and flowering individuals were recorded. In general, shoots within 10 cm of each other were considered to be from a single plant, but sometimes a clear differentiation was not possible. To compare former and recent distribution, old records from the NLWKN (Lower Saxon agency for water bodies, flood protection and nature conservation) and the BfN (Federal Agency for Nature Conservation) were used. To determine the importance of sand accretion (wind-blown sand) to species distribution, relationships to coastal defence dunes as well as habitat types were studied. Results: E. maritimum is recorded from 73 standardised grid cells of about 1.2 × 1.8 km ("Minutenfelder"/grid cells) in Lower Saxony in the period 1981-2022. In more than 50% of these "Minutenfelder" (grid cells) with records between 1981-2015, E. maritimum was confirmed; it was firstly recorded in 16 of 73 "Minutenfelder" (grid cells). The measured population in Lower Saxony is over 55,000 individuals, with the largest numbers on the islands of Spiekeroog and Wangerooge. The most suitable habitats for the species were those characterised by low to moderate sand accretion. Thus, more than 75% of the plants occur in dunes without coastal defence measures or in areas seawards of the coastal defence measures. Dunes which form part of coastal defences are regularly planted more or less with Ammophila arenaria or Calammophila baltica. Regarding the dune series, 85% of the plants are found in the zone from the higher beach landwards to young grey dunes. With succession towards older grey and brown dunes the number of individuals declined. In contrast to the positive impact of sand accretion, rabbits have a negative impact on the population size of Sea Holly. The populations of Sea Holly were larger on islands without rabbits. On islands with high grazing pressure by rabbits (Borkum, Memmert, Norderney, Baltrum, Minsener Oog) no or only very few individuals of Sea Holly occurred. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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