Fen plants and the effects of acidification and water draw-down
Dutch fens have suffered greatly from acidification, eutrophication and the effects of water draw-down. Thanks to restoration measures, however, characteristic plant species are increasing again.
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Trends in fen vegetation
Heath fens are calcium-poor and moderately to severely nutrient-poor water bodies found in the low, wet parts of heath areas. Their characteristic vegetation is under severe pressure from acidification, the effects of water draw-down, and eutrophication. Because fens have limited buffering capacity, acidification has great influence on their water quality: hence the dramatic decline in the distribution of the characteristic plant community of quillwort and water lobelia.
This vegetation is able to recover if the fens are dredged and the hydrology is improved to prevent acidification. In recent years, restoration measures have been implemented in many locations. In the Beuven reserve in Noord-Brabant, for example, this has allowed plants of calcium-poor water such as shoreweed and water lobelia to re-establish.
Trends in shoreweed and water lobelia
Shoreweed and water lobelia are found in weakly buffered fens and in dune pools. In the last 50 years of the 20th century, the number of sites suitable for these species fell sharply because of acidification, eutrophication and the effects of water draw-down. However, since 1990 there has been a dramatic resurgence, especially in sites with shoreweed.
