Keywords:
mainland dunes
lichen heath
forest control
Pinus mugo
Contact: Mr. J. Brandbyge. Email:ag.nm.jbr@aaa.dk.
Mr. P.E. Thystrup. Email: ag.nm.pet@aaa.dk.
Aarhus County. Nature & Environment. Lyseng Allé 1.
DK-8270 Højbjerg.
Location: Denmark, island of Anholt.
The Anholt Desert
The 22 km2 large island of Anholt in the middle of the Kattegat
between Denmark and Sweden is composed of two different parts:
30-50 m high moraine hills in the west, Vesterlandet, shaped by
the inland ice at the end of the last Ice Age, and a large marine
foreland in the east, Østerlandet. Anholt was originally
forested mainly by scotch pine Pinus sylvestris. In the
17th century the inhabitants felled what remained of the forest.
Therefore the former woodland was transformed into a large infertile
area, the so-called desert. However, nowadays the Anholt desert
constitutes the largest, connected area of the north-western European
lowlands containing the rare and very vulnerable type of lichen
heath, connected with large areas of inland dune, heath, crowberry
and grass heaths as well as good-sized white and grey dunes. These
are habitats of European Union interest, and several are classified
as habitats with a high priority, furthermore they include a number
of uncommon and rare species.
Over the last decades, considerable parts of this valuable natural
territory had become heavily overgrown with self-sown mountain
pine Pinus mugo, in total the equivalent of about 25% of
the Anholt desert was under direct threat of being overgrown.
Management
In the end of 1994, a contract was drawn between the European
Commission and Aarhus County and the University of Copenhagen,
to fund a management project partly through the EC’s LIFE Program
to determine the conservational effects of a number of management
methods on the Desert of Anholt during two years time. Several
methods were tested: branch crushing; felling with chain saw connected
with chipping with or without removal of the timber and fine-cutting;
and burning. Weeding started in 1997 and will be repeated every
3-5 years to prevent new growth.
Because of the danger of fire and the inaccessability of the area
it was impossible to burn a considerable amount of the trees to
leave as little organic material as possible in the area. So the
material was left directly on the treatment plots.
Results
Those management techniques resulting in a minimum amount of disturbance
and removal of the above-ground timber are be preferred. The second
best method is burning of the felled material at less sensitive
parts within the area, because of the very nutrient poor ecosystem.
Within the study crushing was 30-40% more effective than chipping
because it is not necessary to fell the trees by chain saw first,
and crushed material may decompose more rapidly due to its greater
surface area. Chips can be used as cover on sandy roads, plantations
and cottage areas. The botanical investigations showed a considerable
decrease in the number of plant species, particulary crypto-gams.
The treatments are expected to stimulate a vegetative succession,
which will reestablish the original heath vegetation. A long-term
monitoring program is established by the University of Copen-hagen.
The first results are expected in 2001-2006.
Anholt
References
- Aarhus County (1994): Re-establishing Lichen and Coastal
Heaths in the Anholt Desert, Denmark. Aarhus County. Højbjerg.
(32R8BN94)
- Aarhus County (1996): Nature Management in the Anholt
Desert. Aarhus County. Højbjerg. (32R8BN96)
- Aarhus County (1997): Nature Management of the Desert of
Anholt. Concluding Report. Aarhus County. Højbjerg. (32R8BN97)
- Christensen, S. N. (1997): Lichen Heaths of the Isle of Anholt.
EUCC-library. (32R8BN97)
- Johnsen, I. (1996): The Heaths at the Island Anholt in Kattegat,
Denmark. Plant Ecological Investigations. Botanical Institute.
University of Copenhagen. (32R8BN96)
