Accelerating urban warming effects on the spring phenology in cold cities but decelerating in warm cities

• Published in: Urban forestry & urban greening 2024-12, Vol.102, p.128585, Article 128585
• Main Authors: Liang, Hangqi, Zhao, Hongfang, Cheng, Wanying, Lu, Yuying, Chen, Yiming, Li, Mengya, Gao, Minyi, Fan, Qunbo, Xu, Ziheng, Li, Xia
• Format: Article
• Language: English
• Subjects: Asymmetrical warming; Soil moisture; Spring phenology; Urbanization intensity; Vapor pressure deficit
• ISSN: 1618-8667
• DOI: 10.1016/j.ufug.2024.128585

Urban is regarded as the ideal natural laboratory for predicting vegetation growth response to future warming, as urban warming promotes the growth of urban vegetation and advances spring phenology. However, the effects of daytime and nighttime warming on the spring phenology of natural vegetation remain unclear under global warming. Here, we used urbanization intensity (UI) as a proxy for future warming, then investigated the start dates of the growing season (SOS) response to daytime and nighttime warming across different levels of UI. We found both nighttime and daytime temperature sensitivities increased significantly from rural to urban centers in cold cities, decreasing in warm cities. It indicated that the advancement in spring phenology of urban vegetation accelerates along with UI in cold cities but slows down in warm cities. Because in cold cities, urban warming and increased humidity accelerate vegetation growth, while in warm cities urban warming and decreased humidity decelerate growth. Therefore, in future we should consider not only the asymmetrical responses of urban vegetation spring phenology to daytime and nighttime warming, but also the disparate responses in different background climate regions under future warming. ●Nighttime warming advances spring phenology more than daytime warming in cities.●The advancement of spring phenology accelerated in cold regions.●The advancement in spring phenology decelerated in warm regions.●Moisture conditions mediate the response of spring phenology to urban warming.●Under future warming, phenological responses depend on the climatic background.