Interface Areas in the European Alps: Defining Functional Regions Between Mountains and Lowlands

The European Alps are surrounded by highly urbanized areas located close to fragile mountain landscapes. The transition areas between the mountain core and peri-Alpine lowlands represent a spatial context where functional linkages and interdependencies are pronounced. Water supplies flowing to lowland populations and weekend tourism flowing to mountain areas are examples of these links. Despite their significance, interface areas remain a underexplored spatial category, with most studies focusing on either mountain or lowland areas. This article addresses this gap by conceptualizing and defining interface areas on a pan-Alpine scale. We had 2 main research objectives: (1) to define and analyze the spatial and functional characteristics of these areas, including their similarities and differences, and (2) to position them in relation to the more established categories of mountain and lowland areas. Our results revealed 3 spatial specificities of Alpine interface areas. First interface areas are characterized by sharp contrasts in socioeconomic and environmental aspects, such as population density, ecological connectivity, and recreational opportunities. Interface areas function as connectors, bridging the divide between high mountain regions and lowland urban areas. Second, interface areas act as geographic funnels, channeling major transport and mobility flows through limited corridors due to spatial narrowing. This leads to hotspots of transport infrastructure demand. Third, policy implications arise from the intense competition for the limited land available within interface areas. Strategic spatial development must balance competing sectoral interests, which requires multilevel governance and participatory processes. The recognition of Alpine interface areas as a specific spatial category provides a new lens for Alpine spatial development.