Green Infrastructure Typologies in Hungarian Functional Urban Areas: A Landscape-Metric Comparison (2012–2018)

Green infrastructure is essential for sustaining urban ecosystem functions, resilience, and biodiversity in rapidly urbanizing landscapes. Although GI has been widely assessed at local urban or national scales, comparative and time-phased analyses at the Functional Urban Area (FUA) scale remain limited, particularly in Central and Eastern Europe. This study addresses this gap by analysing the spatial structure and temporal changes of GI across Hungary’s 19 FUAs using the Urban Atlas 2012 and 2018 datasets. The novelty of the study lies in combining a tailored GI delineation, DEM-derived landform morphology classification, and landscape metrics to identify planning-relevant GI typologies at the city-region scale. A context-specific GI definition was applied, including urban parks and excluding intensive arable fields in order to better capture ecologically functional green spaces. Results show that approximately 44% of FUA land is classified as GI, primarily composed of pastures and forests. Urban areas expanded slightly in all FUAs (+0.39% on average), while pastures and arable lands declined. Cluster analysis identified two persistent FUA types: (1) forest-rich, higher-relief FUAs with larger and less fragmented GI patches, and (2) lowland FUAs with more fragmented and poorly connected GI, requiring targeted corridor development, restoration of small habitat elements, and protection of remaining semi-natural patches.