Resume Les corridors fluviaux constituent des trames naturelles aux multiples fonctions écologiques, mais ces espaces sensibles sont bien souvent menacés par les activités humaines. Identifier les trames fonctionnelles à préserver ou à restaurer est donc un enjeu essentiel pour mettre en place des stratégies de gestion pertinentes qui améliorent la connectivité écologique de ces milieux. Comment la construction d’indicateurs spatialisés peut-il aider à répondre à cet enjeu ? L’analyse de la recolonisation de la loutre sur le bassin versant de la Loire est un exemple des recherches et des analyses menées.
Rivers and their corridors constitute natural networks that strongly structure the landscape. To build knowledge on their conservation status or alterations at large scale, different sources and methods of image analysis nowadays exist. Remotely sensed information can be used for cartography purposes or embedded in spatial indicators that can inform on spatial configuration, fragmentation and continuity, or riparian forest composition. These characteristics are then used to explore the functional relationships between the corridor and different processes and ecological responses through a new regard and network analysis methods.Building homogeneous indicators over the entire French hydrographic network has allowed us to investigate specific and quantitative relationships not only in regard to physicochemical responses (e.g. water quality), but also in relation to the potential spatial distribution of mammals (e.g. otters and beavers). We describe here an analysis concerning otters in the Loire watershed. The presence of wooded riparian corridors combined with a lack of alteration of the physical environment of rivers offer favorable conditions for colonization by this species. Such configurations were mapped while taking into account the density of the hydrographic network. Results identify structural and functional networks which meet the ecological needs of the species at different scales. They provide effective support to guide management strategies aimed at strengthening and protecting such areas.
