The issue of spatial, social or political encounters between cities and parks is central to the UNPEC project and more broadly to the future of biodiversity and the wellbeing of city dwellers in an increasingly urban world. Urbanisation and nature conservation are not set processes fixing borders within the metropolitan structure; they are dynamic processes, underlain by ecological, political, social, economic and territorial logics. In order to account for the mobility and intentionality linked to these processes, we use the concepts of eco- and urban frontiers. Eco-frontier refers to the appropriation of real or imagined spaces by ecological discourses or practices, where such spaces benefit from environmental and aesthetic amenities usually perceived as being highly significant. Urban frontier refers to the spatial extension of urbanisation, whether as urban sprawl or satellite cities, or in the form of recovery and renovation of already urbanised areas. In this chapter, we suggest the possibility that, in an emergent metropolitan context, eco-frontiers intertwine with urban frontiers. Hybridisation becomes essential-as an explanatory notion-in trying to decipher the reality of the cooperation, reconstitution, domination or exploitation links between the two processes.< Leer menos