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Lowering
and restoration
During the past 200 years, human beings have had an impact
on almost all the wetlands in Sweden. Some of them were drained to
create agricultural land, while forests and marshes were drained to
increase forest production. Almost 90 per cent of all the wetlands
in the agricultural landscape in southern and central Sweden have
disappeared.
The shortage of food during the 19th century was an important and
understandable driving force - the people of Sweden were starving!
We have, however, been so efficient that many of the birds' resting
places and breeding places have been destroyed. As a result, many
species of bird that are associated with wetlands, such as ducks and
wading birds, have declined in number.
Lowered five times
Lake Hornborga was also affected and, after the level of the water
had been lowered five times by the 1930s, the lake almost dried out
during the summer. The channels that had been dug quickly led the
water out of the lake and the water meadows around the lake were soon
being cultivated. In spite of this, the amount of arable land that
was recovered was not as great as the companies that were responsible
for lowering the water level had hoped.
The spring flood was still far too large to enable dry land for cultivation
to be created. Instead, the lake started to become overgrown by shore
forests, bushes, sedge and reeds - until it was gradually turned into
a marsh.
One of Northern Europe's most renowned bird lakes was just a memory.
Government decision
Following a government decision, a unique restoration programme began
during the latter part of the 1980s with the aim of recreating a functioning
bird lake. Almost 1,200 hectares of reeds were removed by specially-constructed
amphibious machines, 700 hectares of forest and bushes were cut down
and seven kilometres of channels were dug again. To raise the level
of the water by an average of 85 centimetres, a dam and a three kilometre
long embankment were built on the western side of the lake. In the
autumn of 1992, the water began to be raised and the work was completed
in 1995. After it had been raised, the average depth of the water
in the lake is 0.9 metres. The restoration has now been completed
and no further increase in the level of the water is planned. Work
on maintaining the land in and around the lake is, however, constantly
in progress. Lake Hornborga is part of a living cultural landscape
and, without the grazing cows, which help to keep the shore meadows
open, a great deal would rapidly be lost.
Constant work
The knowledge that has been acquired from restoring Lake Hornborga
is now being passed on. Even the specially-designed machines are being
used elsewhere and large areas of Swedish wetland have been restored
with Lake Hornborga as a role model.
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