Perceptions and Implementations of Urban Green Infrastructures in France: Three Cases of Studies (Paris, Marseille, Strasbourg)

Green infrastructures have gradually become imperative in planning since the end of 1990s in Europe (Jongman et al, 2004). Numerous urban areas in France mobilize and reinterpret the notion according to stakes of their territory (Blanc, 2012). With the promulgation of Grenelle 1 and 2 Laws (in 2009 and 2010), today every local authorities have to integrate an ecological reflection on green infrastructures into its planning projects at metropolitan and local scales, called “trame verte”. To cover a plurality of contexts of cultural, social, geographical and ecosystematic levels, three cities were retained to understand how this reflection is set up: the municipalities of Paris, Marseille, and Strasbourg. Indeed, in Ile-de-France, a number of initiatives reflect the interest of the regional, departmental and municipal authorities for green infrastructures and biodiversity issues: the Seine St-Denis departmental observatory of biodiversity and natural habitats (City hall of Paris, on 2004), the creation of the regional agency Natureparif (2006), the regional strategy for biodiversity (2007), the Paris biodiversity plan (2011). Furthermore, the city of Marseille, influenced by the example of Barcelona metropolitan area and its anellaverda (green ring), plans the development of a green infrastructure on its municipal territory. It confided the study to the Planning Agency of Marseille Urban area (AGAM) which elaborates scenarios for connecting the residual non-constructed spaces, to endow the city of a green infrastructure addressing the environmental issues of sustainable development. Finally, the region Alsace was one of the first regions to integrate a reflection into these environmental policies on green infrastructure in France (in the late 1990s). The Strasbourg local planning in 1992 and the metropolitan plan in 2007 (SCOTER) mention the term “greenway” in their statutory documents. Currently, as part of the development of the urban local plan (PLU), Strasbourg urban community defines a network of greenways in an ecological perspective. Through the consideration of vegetable continuities in town, the notion of green infrastructures brings a revival in the current urban thinking. If scientists in ecological sciences were interested since a few years in this question to fight against biodiversity erosion, green infrastructures appear as a new field of investigation for human sciences. Multifunctionality associated with this notion of meshing offers new challenges as for practices and perceptions of inhabitants. How decision making can take into account and translate their expectations regarding scientific models proposed and political issues? Its diverse dimensions introduce inevitably new modalities of the public debate organization which remain to invent in most cases today. We have compared in each of the studied sites the three following spheres, often distinct from one another: political, scientific and inhabitants