A working definition of 'ordinary nature' adjusted to ecological offset policies tested in three French regions

National audience; Considering the current limitations to re-establishing remarkable ecosystems in ecological offset policies, we suggest that ordinary nature could be more easily recreated and therefore offer a more relevant target for ecological offset measures. The lack of operational scientific characterization of ordinary nature led us to suggest a definition of this notion based on three criteria: nonextraordinary nature, dependency on human activities and low ecosystem complexity. We validated our definition by applying it to three contrasted French regions (Centre, Champagne-Ardenne and Provence-Alpes-Côte d’Azur) in order to delineate the boundaries of ordinary nature. Then, to assess the needs for compensation in these three regions we estimated their potential urbanization by 2040. In order to define the limits of ordinary nature, we used land-cover data and regulated protection areas as indicators of our criteria. Urbanization was estimated by delineating concentric buffer zones around cities based on demographic evolution perspectives and the current city population. The results of our mapping of ordinary nature seem conclusive, excluding areas with major biodiversity issues. Our estimation of urbanization in the three regions highlighted unequal capacities of the three regions to apply ecological offsetting measures.; Considérant les limites actuelles de la compensation écologique pour recréer des écosystèmes remarquables, nous nous fondons sur l’hypothèse que la nature ordinaire serait plus facilement reproductible et donc plus pertinente comme objet des mesures compensatoires. Face à un manque de définition scientifique opérationnelle de la nature ordinaire, nous proposons une clef de détermination de cette notion reposant sur trois critères : absence de nature remarquable, dépendance de fonctionnement vis-à-vis de l’homme et faible complexité. Nous validons notre définition en l’appliquant à trois régions françaises contrastées : Centre, Champagne-Ardenne et Paca. Puis, afin d’évaluer l’adéquation entre besoins de compensation et stock régional de nature ordinaire existante, nous estimons l’artificialisation potentielle de nos trois régions d’étude à l’horizon 2040.