Origin-destination flow clustering for sustainable forest recreation planning – case study of Vienna Metropolitan Area, Austria

Urban and suburban forests deliver key ecosystem services. Understanding how residents reach them is essential for sustainable recreation planning, yet destination-only assessments miss the way origins and routes shape realised use. This study analyses origin–destination (OD) forest recreation flows in the Vienna Metropolitan Area to make those links explicit. We use representative Public Participation GIS (PPGIS) data from 3,121 residents, linking residential origins to mapped forest entry points. OD flows are clustered with density-based algorithms (DBSCAN/HDBSCAN) and paired with accessibility metrics: Euclidean distance and mode-specific network travel times for walking, cycling, public transport, and car. It resulted in six major clusters that capture distinct geographies and mobility regimes. Each additional kilometre between home and forest corresponds to about 11% fewer annual visits, with the steepest distance decay within 5 km. Corridor structure matters: multimodal belts around the urban edge keep most PT/cycling trips within 60 minutes, while peripheral patterns depend on car access and show markedly lower visitation. OD flow densities are lower in parts of the eastern/northern metropolitan area, consistent with connector and last-mile constraints alongside population distribution and destination differences. OD clusters were characterised by neighbourhood attributes, built form, and amenity reachability to interpret these disparities in travel time, mode share, and visit frequency. This corridor-based lens advances destination-centric assessments by revealing how origins, routes, and thresholds jointly govern forest use. Findings inform sustainable recreation policy and planning: strengthening connectivity, protecting multimodal corridors, and targeting accessibility gaps can lift usage without inducing car dependence.