Bavarian Forest
National Park

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Renaturation of streams

Renaturation of streamsi (Photo: Ingo Brauer)

Streams and their source areas in the national park have maintained a comparatively near natural character despite the numerous and varied interventions in the past. From a water ecology point of view they are today – apart from the problem of acidification – of a consistently high quality. The habitat is rare in the area and possesses a particular importance as an aquatic ecosystem. Many species typical of the region live here, some of which are extremely endangered (otter, common sandpiper, white-throated dipper, bullhead fish).

Numerous changes to streams were undertaken above all to facilitate timber transportation. It wasn’t just that the courses of streams were straightened or their embankments strengthened. In order to have sufficient water available to transport timber, damming structures (barriers, logging dams) were built in the streams’ upper courses and sometimes water courses were moved.

Renaturation measures are concentrated therefore on getting rid of structures on the embankments, if without human assistance they will inhibit the natural dynamic of the water for a long time to come. In addition there are a few cases where straightening and shortenings should be reversed.

Particularly important for their ecological effectiveness and functioning as linear habitats and migratory corridors is the passability and flow of the streams. The attainment of a long term improvement in the situation is sought using differing measures:

- At the damming structures bypass channels (fish steps) are added;
- In the course of forest road renaturation canalisations are being opened;
- In the field of further necessary path networks water drops are avoided by pipe culverts;
- Conveyances with passable river floors (bridges; Half shell pipes) pursued;

The success of these measures for a better flow in the streams is though very much dependent on the condition of the middle and lower courses outside the national park.

In connection with the renaturation of streams, the restoration of the original forest community accompanying the stream, shall be provided, for example through getting rid of purely spruce forest stands and allowing natural succession. In individual cases recolonisation with lost species of flora (e.g. grey alder) by artificial planting can be carried out .