- „habitat corridors"
- hinterland connection A21
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One example of successfully turning land near the otter tunnel into a more wildlife friendly environment is the road agency’s compensation fields bordering small river Brandsau (called Lehmwiesen) that were formerly used for intensive arable farming (the land had originally been raised peat bog!). These are now extensively managed, low input grasslands that should encourage less mobile species of amphibians and reptiles to establish themselves.
Much additional work was necessary during the project to convert the land from intensive arable use. Ditches and drains were blocked to raise the water table to its historic level and re-wet the land. Furthermore, remedial work was carried out to restore existing water bodies and new ones were created. Shallow scrapes were excavated to create seasonally wet areas, and the excavated soil was used to create small sand hills.
It is expected that the several species, for instance the herpetofauna that includes moorfrog (Rana arvalis), great crested newt ( Triturus cristatus), common spadefoot (Pelobates fuscus) and European adder (Vipera berus), can increase their populations in the environment surrounding the culverts.
With the growing populations, the number of migrating animals is going to increase and the likelihood that migrating animals will use the culverts to reach suitable sites beyond the autobahn is also strongly increased.
The actions fulfil the compensation aims stipulated in the planning permission. East of the A21, the formerly raised bog soils are still under intensive agricultural use. There, water management measures (WRRL) were implemented at the Brandsau river and on a riparian strip, approximately ten metres wide.
Further wildlife-friendly environment has been created on patches of ungrazed wasteland within the state forestry in the Brandsau lowland. These act as stepping stones to encourage access to the culverts.