Promoting ecological management of riparian forests on the Drôme River, France

Authors

  • H. Piégay,

    Corresponding author
    1. CNRS-UMR 5600 ‘Environnement-Ville-Société’, 18 rue Chevreul, 69362 Lyon cédex 07, France
    • CNRS-UMR 5600 ‘Environnement-Ville-Société’, 18 rue Chevreul, 69362 Lyon cédex 07, France
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  • N. Landon

    1. CNRS-UMR 5600 ‘Environnement-Ville-Société’, 18 rue Chevreul, 69362 Lyon cédex 07, France
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Abstract

 1. Riparian forests, because of their multiple ecological and dynamic functions, have become a subject of particular interest for managers. This is the case in France following the Water Law of 3 January 1992 and the development of the ‘Schéma Directeur d'Aménagement et de Gestion des Eaux (SDAGE)’ (Planning and Management—Master Plan—of Water Resources) in various sub-catchments of the Rhône. Within this framework, the major themes of ecologically integrated riparian forest management have been developed on a 110 km section of the Drôme river, a piedmont tributary of the middle Rhône river, in south-eastern France.

 2. The geographical expansion, diversity and evolution of riparian forest within this section of the Drôme since 1948 have been studied. The transport of woody debris, which is characteristic of forest hydrosystems, has also been taken into consideration as managers were concerned by its recent increase.

 3. The recently developed vegetation corridor, measuring nearly 710 ha, is threatened by reduced bedload availability leading to channel incision and the disconnection of the floodplain from the active band of the channel, as well as reduced vegetation renewal.

 4. Several management proposals have been put forward in an effort to maintain riparian ecosystem dynamics without simultaneously increasing flooding and erosion risk: (i) legal measures to conserve the most functional sections, (ii) replanting a vegetation corridor at least 5 m wide in farming areas, (iii) impeding the breaking-up of the most interesting vegetation corridors into small parcels of land, (iv) urgently encouraging the regeneration of vegetation margins and renewed sediment transport, namely by creating artificial overflow channels in forested areas or by clearing certain sectors of the active channel.

 5. It has been proposed that vegetation maintenance and logjam removal, today recognized as detrimental from an ecological standpoint, be conducted selectively on the basis of management appraisals of certain sectors. Certain reaches will no longer be subject to maintenance on the grounds of their great ecological value and because of their low risk of flooding impacts. ©1997 John Wiley & Sons, Ltd.

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