Keywords:
island barrier dunes
management
mowing
sod-removal
grazing
hay-making
Contact: M. Annema. Delta Nutsbedrijven. P.O. Box
5048. 4330 KA Middelburg. The Netherlands.
Location: The Netherlands, Goeree
The Middel- and Oostduinen of Goeree
The dunes of the former island Goeree are situated in the southwestern
part of the Netherlands. This part includes the coastal sand dune
stretches bordering the western tips of the islands south of Hoek
van Holland, only consisting of Younger Dunes. The region as a
whole is an estuarine area, the dunes border not only the North
Sea but also parts of the estuaries. The dune sand is quartz sand
of riverine origin (rivers Rhine and Meuse) and somewhat finer
than that along the northern coasts of the Netherlands.
The Middel- and Oostduinen (altogether 204 ha) are dune areas
with a modest relief, but they are rich in gradients, both on
macro- and micro-scale. The Oostduinen are mainly calcareous whereas
the northern part of the Middelduinen is calcareous and slightly
acid to alkaline and the southern part limestone-poor and acid.
Already in the first part of this century, the area was reknowned
for its large variation in plant communities. Since 1935, the
dune area is used as a water-abstraction area by Delta Nutsbedrijven
which has a great impact on the groundwater regime in the whole
Oostduinen and the central part of the Middelduinen.
Management
In the 1970s grazing and water abstraction were stopped with the
consequence, that vegetation deteriorated and many rare species
disappeared. In 1982, the water company Delta Nutsbedrijven initiated
a management plan aimed at the return of the disappeared species.
The basic management tool of the Middelduinen and of a part of
the Oostduinen (altogether 116 ha) is grazing. In the Oostduinen
grazing by sheep failed but grazing with Charolais cows is successful.
Strongly eutrophic slacks were mown with the so-called ‘Spragelse-combination-wagon’.
This machine cuts the vegetation and removes even the litter-layer
and shrubs. Sod cutting of thick organic layers is carried out
by cranes, just down to the level of the mineral soil. Due to
water abstraction, limestone-rich and nutrient-poor sand reaches
the soil surface, giving rise to calcareous pioneer conditions.
Furthermore, in 1997 a recharge canal was re-arranged into a more
natural look. From 1991 to 1997 the area was monitored.
Results
In areas with high micro-topographical variety a combination of
management measures is required for the restoration of the complete
vegetation gradient. Sod cutting and excavation creates bare soils,
poor in nutrients and organic material and have the most distinct
impact on the occurence of rare pioneer species of the Anthyllido-Silinetum
nutantis, the Littorelletea and the Nanocyperion.
The Junco baltici-Schoenetum nigricantis and most of the
Littorelletea-species are only favoured by sod cutting
because excavation removed their shallow soil seed bank. Grazing
and / or hay-making retard vegetation succession or create small
open patches. They have the largest impact on the Botrychio-Polygaletum,
the Polygalo-Koelerion, the Taraxaco-Galietum veri,
the Festuco-Galietum maritimi and the Thero-Airion.
A combination of sod cutting and hay-making is advised for wet
or moist conditions where base-rich groundwater discharges during
winter and early spring.
References
- Annema, M. & A. Jansen (1998): The recovery of endangered
plant communities in Goeree (NL). Coastline 4: 17-19.
- van der Meulen, F. & E. van der Maarel (1993):
Dry coastal ecosystems of the central and southwestern Netherlands.
In: van der Maarel (ed.). Ecosystems of the world 2A: 271-306.
Elsevier. Amsterdam-London-New York-Tokyo. (BN93).
