Keywords:
island barrier dune
natural development
education
Contact: National Park administration ‘Waddensea
of Lower Saxony’. Virchowstr. 1. 26382 Wilhelmshaven. Germany.
Location: Germany, Eastfrisian Islands
The island Memmert
The island Memmert is situated in the Waddensea of Lower Saxony
in the south of the western end of the island Juist. The ‘Memer
Sandt’ as a sand plate is first mentioned in 1585 as a part of
Juist. Approximately 60 years later it was cut off from the island,
but reports about the development of long-living dunes on the
‘Island Memmert’ can be first found in the middle of the 19th
century. Nowadays Memmert covers an area of approximately 200
ha with the highest elevation of approximately 8 m, the so-called
‘Nordduenen’. The core of the island is constantly shifted in
an eastern direction. Apart from one house for an ‘Inselvogt’
(island guardian) the island is not inhabited.
Management
In
1908 the teacher Otto Leege from Juist with aid from the ‘national
building administration’ started to support the development of
dunes on Memmert. They constructed fences of reed for sand catchment
and planted marram grass. The aim was to colonize the island with
seagulls (Larus spec.). These birds enrich their habitats
with the nutrient N which fertilizes vegetation for dune development
(see also: Nutrient input by the herring gull (Larus argentatus)
on Mellum, German North Sea). The experiment
was very successful and because additionally the island has a
positive sand budged, the size increased rapidly from 8 ha in
1906 to 200 ha in 1995. Apart from that, the island is nearly
free from human influence with respect to management. As the island
has no function for coastal protection further measures are not
even planned. Previous management practices have hardly left obvious
influence because no basic geomorphological structures were changed.
Nowadays the basic aim for management is to maintain the natural
development.
Results
Memmert has been a well-known bird habitat for more than 100 years.
Because of that, the island became a nature reserve in 1924. The
island is of international importance with respect to occasional
birds and of national importance for breeding birds. In 1995 all
in all 42 breeding species could be found, of which 13 were on
the Red List for endangered species. Furthermore 16 pairs of the
little tern (Sterna albifrons) were be counted. This species
is threatened to become extinct.
The vegetation on Memmert shows communities typical for dunes
and salt marshes of the coastline of the Eastfrisian islands.
Vegetation of beach and dry dunes (xerosere), of salt marshes
(halosere) and of reed from brackish water (hygrosere) can be
found. The succession seems to be progressive for the halosere,
but regressive for the xerosere. That means, that the island tends
to develop from a dune area to a so-called ‘heller’ (salt marsh).
Memmert also has great importance for the National Park ‘Waddensea
of Lower Saxony’ itself because it is a good example for a marginally
influenced dune-island with its vegetation communities typical
for the Eastfrisian Wadden Sea. The island offers the possibility
to do research work about natural dynamics and to use the experiences
for informational or educational work, one original intention
of a National Park itself.
Natural development of the island Memmert
References
All References are published in: Schriftenreihe Nationalpark Niedersaechsisches
Wattenmeer. Band 2. Beitraege des Workshops ‘Natuerliche Dynamik
oder Management fuer den Naturschutz’ vom 8.8. – 10.8.1996 in
Dornumersiel. (31BCD97).
- Coldewey, H.G.: Die Duenenentwicklung der Insel Memmert.
39-43.
- Mennebaeck, T. & R. Schopf: Die Bedeutung der Insel Memmert
fuer die Vogelwelt. 44-48.
- Oltmanns, B.: Die Vegetationsentwicklung auf der Insel Memmert.19-27.
- Stephan, H.J.: Die Entwicklung der Insel Memmert als Folge
grossraeumiger und langfristig gerichteter morphologischer Veraenderungen.
2-18.
- Zander, R.: Natuerliche Entwicklung als Management-Ziel im
Nationalpark ‘Niedersaechsisches Wattenmeer. 36-38.
