PROJECT DESCRIPTION
BACKGROUND
The Lac du Bourget was formed during the ice age. It covers around 44 km² and reaches a depth of 145 m. In the southern part of the lake there are still good examples of the Magnopotamion and Hydrocharicion formations, which are of Community interest, whereas such formations have regressed considerably on the Lakes of Geneva, Neuchâtel and Annecy. The most outstanding species present include small populations of Emys orbicularis(under the lake), Bombina variegata, Maculinea teleius and Lyceana dispar, which are listed in Annex II of the Habitats Directive.
The main threat has arisen from the regularisation of the level of the lake since 1982. This is causing a considerable lowering of the water level and bank erosion phenomena which are weakening the existing vegetation belts and preventing their development. The arrival of large amounts of floating waste on the south bank of the lake and unregulated human activities (mooring, bathing, walking, and lakeside amenities) are making these habitats even more fragile. Since 1998, the Lac du Bourget has been covered by a "large lake" programme contracted by the regional and national authorities, which combines environmental, tourism and landscape concerns.
OBJECTIVES
This project followed on from a previous LIFE project which resulted in the drafting of the objectives document for the future Natura 2000 Site (management plan in accordance with Article 6 of the Habitats Directive). Its aim was to test and implement techniques for the restoration of lake eco-systems. The project planned to extend the area of hydrophytes by 100 ha on 8 km of bank. To do so, it was foreseen to reconstitute areas of shallow water and set up breakwater systems. A timetable was to be drawn up for the optimum management of the water level of the lake. 30 hectares of low marsh and meadow were to be restored and managed in such a way as to promote the presence of the above-mentioned insect species. An operation to re-introduce the box tortoise was also to be tested and used as a basis for drawing up a re-introduction strategy which could be applied elsewhere. Eventually, an international seminar and a film describing the measures taken were planned to spread the results of the project.
RESULTS
The main results of this LIFE project were the followings:
A very precise cartography of the aquatic vegetation of the lac du Bourget, which covers a surface of 320 ha has been drawn up. This was the first general inventory of the lake’s macrophytes and, on its basis, the priority areas could be identified for conservation purposes. The project tested and implemented techniques for the restoration of lake ecosystems: breakwater systems were set up in the south part of the lake where the swell is the heaviest. It consisted in mineral islets or vegetal deflectors protecting the shore and the remnants of the aquatic vegetation that was reinforced by planting in order to improve the results of the restoration of the area. The first results show that this operation has led to better conditions for the aquatic vegetation and fauna species (birds and fish). A management plan of the seven main areas of the lake for the conservation of hydrophytes and reedbeds has been produced. The proposed restoration measures have been accepted and adopted by the steering committee. The measures planned (for a budget of 1.5 million euros) are already supported by another programme called "contrat de Bassin du lac du Bourget". An operation for the re-introduction of the box tortoise (Emys orbicularis) has been successfully tested. During the project, 37 radio-tagged individuals have been released in marshes in the southern part of the lake. The first years of monitoring have yielded several encouraging results: the first breeding attempts have already been observed in the sand dune built in this purpose and all the individuals monitored have wintered in the release ponds. On the basis of these results, a re-introduction strategy has been drawn up, which could be applied to other sites. An international seminar on the lake management and the conservation of the littoral vegetation was held in October 2002, with 120 participants from 5 European countries (France, United Kingdom, Germany, Netherlands, Switzerland). The seminar led to the adoption of a motion stressing the need for natural fluctuation in regulated lake ecosystems and especially the drawdowns at the end of summer. This motion should support lake managers in their task, such as the Conservatoire du Patrimoine Naturel de la Savoie, whose action after the Life Nature project will be to implement ecological engineering, but also to re-negotiate water level regulations over the lac du Bourget. The main results of this LIFE project were the followings: A very precise cartography of the aquatic vegetation of the lac du Bourget, which covers a surface of 320 ha has been drawn up. This was the first general inventory of the lake’s macrophytes and, on its basis, the priority areas could be identified for conservation purposes. The project tested and implemented techniques for the restoration of lake ecosystems: breakwater systems were set up in the south part of the lake where the swell is the heaviest. It consisted in mineral islets or vegetal deflectors protecting the shore and the remnants of the aquatic vegetation that was reinforced by planting in order to improve the results of the restoration of the area. The first results show that this operation has led to better conditions for the aquatic vegetation and fauna species (birds and fish). A management plan of the seven main areas of the lake for the conservation of hydrophytes and reedbeds has been produced. The proposed restoration measures have been accepted and adopted by the steering committee. The measures planned (for a budget of 1.5 million euros) are already supported by another programme called "contrat de Bassin du lac du Bourget". An operation for the re-introduction of the box tortoise (Emys orbicularis) has been successfully tested. During the project, 37 radio-tagged individuals have been released in marshes in the southern part of the lake. The first years of monitoring have yielded several encouraging results: the first breeding attempts have already been observed in the sand dune built in this purpose and all the individuals monitored have wintered in the release ponds. On the basis of these results, a re-introduction strategy has been drawn up, which could be applied to other sites. An international seminar on the lake management and the conservation of the littoral vegetation was held in October 2002, with 120 participants from 5 European countries (France, United Kingdom, Germany, Netherlands, Switzerland). The seminar led to the adoption of a motion stressing the need for natural fluctuation in regulated lake ecosystems and especially the drawdowns at the end of summer. This motion should support lake managers in their task, such as the Conservatoire du Patrimoine Naturel de la Savoie, whose action after the Life Nature project will be to implement ecological engineering, but also to re-negotiate water level regulations over the lac du Bourget.
