Renaturation of Alluvial Forests at the Lake Constance

Back in the 19th century the Lake Constance still possessed wide natural shorelines. Today, in contrast, 50 % of the Lake's banks are thoroughly covered with buildings and significantly modified (IGKB, 2004). The anthropogenic intervention especially affected mouths of rivers and streams as well as the vegetation that accompanies them - riparian forests (mostly silver willow forests). Due to regulation, run-cuts, construction of dams, revision of land use, only rare areas of softwood riparian forests remain preserved, especially at the mouths of the Lake Constance feeder rivers. The riparian forests' remainders are additionally significantly overaged. Pioneering locations for re- juvenation of willows are not available due to the lack of river dynamics.

Riparian forests with alders, ash trees and willows are prioritized biotopes according to the Fauna-Flora-Habitat Directive (biotope type 91E0). They grow in areas characterized by frequent temporal flooding.

On the one hand, climate change and extremely changeable water levels has negatively affected the water balance of remaining riparian forests. On the other hand, a longer period of low-water years created new potential riparian forest areas on the shores of Lake Constance. But their expansion contradicts other interests of nature conservation and land use. So far there was no comprehensive and trans-boundary protection strategy for the Lake Constance region.

Goals of the project
The long-term goals are re-naturalization of riparian forests, rejuvenation of existing riparian forests along the Lake Constance shore, and an improved connection with the inland, especially with the mouth areas of the Lake Constance feeder rivers. The project makes a contribution towards the preservation of bio-diversity and the natural water changing zones of Lake Constance.

In the frame of potential analysis, a study of re-naturalization potential and linking-up possibilities for riparian forests in the entire Lake Constance area, especially in river mouths sites, would be accomplished. Based on results of the potential analysis six most promising and representative riparian forest areas will get feasibility studies, with propositions for concrete actions towards re-naturalization. The following implementation and accompanying measures should be realized in Germany and Austria as EU-LIFE+-Projects. The implementation in Switzerland should be carried out by the Swiss assisting institutions.

The project makes a contribution towards the improvement for trans-boundary cooperation between the public authorities responsible for nature conservation and watercourses in Germany, Austria and Switzerland (agreement on common middle-term goals for nature conservation and biodiversity, establishment of work structures, a common strategy for communication etc.).

The project is a constitutive contribution towards the implementation of the Fauna-Flora-Habitat Directive, the EU Water Directive, the EU and national strategies towards biodiversity. Time schedule: beginning autumn 2008/ duration 18 months

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