Résumé
The current context of loss of biological and cultural diversity, and the alteration of our ties to nature and to each other, calls for a reconsideration of our place in the biosphere, and of our tools for nature conservation, among which protected areas play an important role. The principle of ecological solidarity first appeared in the 2006 law reforming France's national parks, with the aim of improving their local roots. In this law, ecological solidarity refers both to a de facto state of interdependence between the core of the Park and its optimal membership area, and to the basis of the contract between the core and the communes that choose to adhere to it. More broadly, the principle of ecological solidarity invites us to think about socio-ecosystems through the prism of ecological, socio-ecological and socio-political interdependencies between stakeholders with regard to nature, in order to build territorial projects that express solidarity between humans and with nature. The aims of this thesis are (1) to clarify the originality of the principle of ecological solidarity for action in the territories; (2) to assess the appropriation of this principle by the National Parks, and to evaluate its added value for the Regional Natural Parks; and (3) to explore some tools to highlight these interdependencies and their implications on the territories. We show that the National Parks mobilize the principle of ecological solidarity mainly by normative injunction, but struggle to apply it concretely in their projects. Over and above the principle of ecological solidarity, the Regional Natural Parks contribute to building solidarities combining social, economic, ecological and territorial elements through their actions on their territories. The added value of the principle of ecological solidarity lies in its entry through interdependencies for action in territorialized social-ecological systems. However, due to technical, scientific and administrative obstacles, it is this transformative dimension that Parks are still struggling to grasp. Explicitly eliciting interdependencies by working on the mental models of territorial stakeholders and focusing on individual links to the territory and to nature in the Parks, are tools for understanding the interdependencies to be considered when building ecological solidarities.