Nonuniform response of vegetation phenology to daytime and nighttime warming in urban areas

The phenological response of vegetation to changing climates requires exploration across environments, including urban areas with elevated daytime and nighttime temperatures (T_D and T_N) and artificial lights. Here, we analyzed multiple remotely-sensed datasets (2012–2021) from and around a highly-urbanized area, Seoul, in South Korea. While the urban fraction and artificial lights largely contributed to advancing the start-of-season (SOS) and delaying the end-of-season (EOS) (30.7–42.1%), SOS changes were more driven by T_D (15.7%), whereas EOS changes were more attributed to T_N (21.8%). A higher response of the SOS to T_D was found in more urbanized areas with higher artificial lights, while the sensitivity of the EOS to T_N increased in brighter areas during nighttime. These findings indicate that vegetation’s response to rising temperatures will become dynamic, given the potential constraints by light and other attributes, calling for further assessments of its implication for terrestrial ecosystems and carbon cycle.