Spatio-temporal assessment of urban vegetation cooling efficiency and the identification of critical heat mitigation zones in Kraków, Poland

Urban Heat Islands (UHIs) pose growing challenges to urban sustainability, affecting health, energy use, and climate resilience. While urban vegetation cools cities, planners lack tools to prioritize interventions that combine current cooling performance with long-term vegetation health trends. This study develops a novel dual-criteria spatial prioritization framework that integrates modeled current cooling performance from the InVEST Urban Cooling Model (2024) with long-term NDVI trends (MODIS, 2003–2024) to identify priority classes for heat mitigation in Kraków, Poland. Results show a moderate positive association between NDVI and the Heat Mitigation Index (HMI; r = 0.566), with tree cover providing the greatest cooling (HMI: 0.57–0.71). Importantly, 9.37% of vegetated areas showed statistically significant declines in NDVI ( p ≤ 0.05), mainly in urban cores. Spatial integration of these layers identified five priority classes for heat mitigation. Highest-priority zones covered 1627.18 ha (4.99%) of the study area, while high-priority zones accounted for 6107.14 ha (18.72%). This spatial prioritization approach enables cities to optimize greening strategies by addressing current deficits and areas of ongoing vegetation decline, supporting proactive, evidence-based urban climate resilience.