Contrasting spatial and temporal climate responses of ornamental tree phenology: a social media-based study across Chinese cities

Background Urban ornamental tree phenology provides critical seasonal landscape services, yet how phenological timing responds to climate variability—particularly across different spatial and temporal scales—remains insufficiently characterized. Methods This study investigated the spatiotemporal heterogeneity and climate responses of Yoshino Cherry peak flowering date (PFD) and Ginkgo peak leaf coloration (PLC) across six Chinese cities during 2014–2024. Phenological data were retrieved from user-generated content (UGC) on social media platforms, and climate-phenology relationships were analyzed using Pearson correlation and principal component regression (PCR). Results Both phenophases exhibited significant spatial variation among cities and prominent interannual fluctuations with relatively weak temporal trends. Crucially, climate-phenology relationships exhibited contrasting patterns between spatial and temporal scales. For PFD, spatial variation was temperature-driven with earlier PFD associated with higher winter–spring temperatures, whereas interannual variability was precipitation-driven in most cities except for coastal Dalian. For PLC, temperature and precipitation jointly regulated coloration, with temperature effects reversing across scales: warmer conditions were associated with delayed coloration spatially but advanced coloration temporally. PCR analysis further revealed regional divergence in PLC’s response to climate variability, with temperature dominating in central-eastern cities and precipitation in western inland cities. Conclusion These contrasting response patterns between spatial and temporal scales suggest that “space-for-time substitution” approaches have limited validity for urban phenological research. The findings revealed the complex climate sensitivity of urban ornamental tree phenology across scales and regions, which could inform phenological prediction and seasonal landscape management of urban forests under climate change.