Sciences, Eaux & Territoires (Mar 2012)
Les enjeux de l’équivalence écologique pour la conception et le dimensionnement de mesures compensatoires d’impacts sur la biodiversité et les milieux naturels The issue of ecological equivalence in designing and sizing appropriate offsets for impacts on biodiversity and natural habitats
Abstract
L’évolution du contexte réglementaire a renforcé l’obligation de compenser «en nature» les impacts sur la biodiversité qui n’ont pas pu être évités ou réduits. Dans ce contexte, l’évaluation de l’équivalence entre les pertes causées par ces impacts et les gains de biodiversité attendus des actions de compensation suscite des questions scientifiques et techniques quant aux concepts et connaissances à mobiliser et aux méthodes d’évaluation à développer et mettre en œuvre.Since 2007 France has seen a radical strengthening of its legislation concerning the mitigation of development impacts on biodiversity and ecosystems. Under pressure from the European Union and as an outcome of a national consultative process called the “Grenelle de l’Environnement”, the scope of the mitigation hierarchy of avoiding, reducing and offsetting impacts of plans, programs and projects has been expanded. It now includes stronger requirements in terms of monitoring and effective implementation. These changes – which have strong financial and legal implications for developers - have revealed the lack of technical guidelines for designing and sizing offsets. Assessing the ecological equivalence between losses caused by impacts and the gains expected from offset actions raises scientific and technical issues that remain unresolved. These include the identification of relevant components of biodiversity, the development of appropriate indicators, the identification of reference states and the incorporation of ecological dynamics and uncertainties into offset design and sizing.