The origin of alkaline fen in the Mosbeek Valley in the Netherlands is due to human impact rather than a natural development

Alkaline fens are important Natura 2000 habitats, which harbor many endangered plant species. Alkaline fens are formed in areas with groundwater discharge and usually developed in a natural way in the early Holocene. We radiocarbon dated the base of three peat deposits from spring fens along the fla...

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Bibliographic Details
Published in:Holocene (Sevenoaks) 2022-07, Vol.32 (7), p.613-623
Main Authors: Smeenge, Harm, Kooijman, Annemieke, Brinkkemper, Otto, Mars, Hans de, Mauquoy, Dmitri, van Geel, Bas
Format: Article
Language:English
Subjects:
Deforestation
Endangered plants
Endangered species
Evaporation
Fens
Groundwater
Groundwater discharge
Groundwater levels
Harbors
Holocene
Human impact
Human influences
Land use
Paleoecology
Pasture
Peat
Plant species
Plateaus
Privatization
Radiocarbon dating
Rare species
Runoff
Sediment deposits
Seepage
Valleys
Vegetation
Water levels
Water springs
Water use
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Summary:Alkaline fens are important Natura 2000 habitats, which harbor many endangered plant species. Alkaline fens are formed in areas with groundwater discharge and usually developed in a natural way in the early Holocene. We radiocarbon dated the base of three peat deposits from spring fens along the flanks of the ice-pushed ridge near the village of Ootmarsum to find out when and why peat-forming vegetation started to grow. We cored a sequence in the Mosbeek Valley for detailed paleoecological analyses of micro- and macrofossils. To our surprise, we found strong evidence for human impact during the 13th and 14th centuries AD as the triggering factor for starting organic colluvial accumulation and peat growth at sites where natural springs are present. This shows that this fen is not a relic, but results from changes in land use. Human actions were: (1) deforestation causing increased run-off and reduced evaporation on the plateaus by the vegetation, resulting in increased seepage in the valleys, (2) intensification of agriculture, trade routes, and paired erosion, which formed colluvial deposits and sediment fans that hampered fast run-off water, (3) increased back and groundwater levels after the foundation of watermills; four lowering water levels due to intensification and reorganization of water use by new watermills, and (4) head cut erosion and spring erosion after privatization and cultivation of common pastures after the mid 19th century. This means that cultural-historical changes in the landscape were much more important for alkaline fens than expected.
ISSN:0959-6836
1477-0911
DOI:10.1177/09596836221088230