Territories in-between (TiB) have gained increased attention the past decades among researchers in the field of urban planning and design. These territories are identified as territories somewhere in-between the urban and rural. Typical land uses in the TiB are warehouses, sport complexes, allotment gardens and small-scale industrial activities. The TiB are often considered to be underused, lack spatial quality (sense of place) and are under mounting pressure of urban densification. However, the rich diversity of land uses and abundance of semi open spaces in the TiB provides unique habitats and social-ecological opportunities, different from exclusively urban and rural landscapes. Therefore we, as urban planners and designers, should reconsider conventional planning and design approaches towards these territories and acknowledge the social and ecological potentials of these territories.

The thesis project proposes an unconventional design perspective that makes space for the territory in-between and embraces its true unorganized and multi-functional nature. The design strategy that was developed through a research by design process is called: the recovering membrane and describes the vision for the territory around the urban fringes of the city that resembles the functioning of a membrane at landscape scale. This design strategy was developed in particular for the city of Rotterdam. The recovering membrane is defined as a spatial layer of interaction between two distinctive living environments –urban and rural- and various human and non-human actors in them. The membrane aims to bridge the urban-rural divide, enhance biodiversity and sense of place in the in-between territories at the urban fringes of the city. The proposed strategy is supported by landscape ecology theories on ecological edges and boundaries and a theory on sense of place experience emphasizing the importance of human-nature interactions.

By using these theories, the vision for the recovering membrane is elaborated at local scale for an in-between territory near Hoek van Holland. The research shows that nature-inclusive spatial design elements can mutually benefit the ecological quality of the in-between territory as well as the sense of place experience at local scale. This integrated design approach is described as nature-based placemaking. The spatial transformation of the in-between territory into a membrane landscape can be organized into three development stages at respectively: short, medium and long time period. (1) Engagement and activation of the local community through a nature-based placemaking process. (2) Connectivity and integration of the in-between territory within its surroundings through social-ecological corridors. (3) Re-distribution of clustered land-uses in order to strengthen the heterogeneous nature of the in-between territory. The latter is of specific importance as it seems that greater landscape heterogeneity does not only cause for greater ecosystem resilience and biodiversity, but also greater sense of place experience. To enable this new approach a new governing body is proposed: the Membrane Management Group.