A comprehensive “past-future” framework for restoration priority areas identification in a coastal city: a case study of Tianjin

Coastal cities are highly urbanized regions where ecological sensitivity and the continuous expansion of urban space pose significant challenges to the sustainable development of ecosystems. This study assessed ecosystem services (ESs) from an integrated past–future perspective and elucidated spatiotemporal evolution patterns, as well as trade-offs and synergies among multiple ESs in Tianjin over the past two decades and under three future scenarios. The results indicated that, from 2000 to 2020, ESs showed a declining trend, although localized improvements were observed in the peripheral zones of ring-shaped built-up areas and in coastal wetland regions. Spatial trade-offs remained the dominant pattern among ESs, although their influence was gradually diminishing. In contrast, spatial synergies increased significantly. By integrating ESs supply, spatial distribution patterns, and future trends, we identified and delineated ecological restoration priority areas (RAPs), which were classified into three sequential categories: Core Conservation Zones, Synergistic Optimization Zones, and Ecological Improvement Zones. Based on a comprehensive analysis of land-use composition and its spatial distribution within RAPs, we proposed targeted ecological restoration strategies and spatial planning recommendations. This study provides scientific spatial guidance for ecological restoration and sustainable land management in coastal cities by identifying and prioritizing RAPs.