Urban ecological health is increasingly prioritized in Europe, as reflected in the EU Biodiversity Strategy 2030, the Nature Restoration Regulation, and the amendment to the Regulation on Environmental-Economic Accounts. Translating this ambition into greening actions that halt and reverse urban ecological degradation requires standardized, spatially explicit indicators. This study explores the utility of the System of Environmental-Economic Accounting-Ecosystem Accounting (SEEA-EA) framework for developing thematic urban ecosystem accounts as integrated metrics to inform urban greening in the Western Balkans. We constructed pilot accounts for the Western Balkans for 2018, with particular focus on Horizon-funded CROSS-REIS countries, where local accounts were also developed for representative municipalities (Kranj, Rijeka, Nis, Podgorica, Tirana). The accounts quantify ecosystem extent, four condition metrics (imperviousness, green space, tree cover, and PM10; concentration), and the service air filtration using PM10; deposition onto vegetation as a proxy. Results were benchmarked nationally against EU/EFTA/UK countries and locally against Italian municipalities of the National Biodiversity Future Centre project. The analysis reveals that urban ecosystems in the Western Balkans exist on a continuum with other European countries but exhibit a distinct, more homogeneous profile shaped by geography, climate, and policy legacies. The accounts identify ecological degradation hotspots (e.g., high soil sealing) and areas of high service-delivery capacity, supporting translation of spatial diagnosis into targeted greening priorities. Overall, the study shows that thematic urban ecosystem accounts offer a standardized, multi-scale evidence base to inform and monitor urban greening policies, supporting the Western Balkans in their environmental management needs and on their path toward EU integration.
