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

Abstract

The phenological response of vegetation to changing climates requires exploration across environments, including urban areas with elevated daytime and nighttime temperatures (TD and TN) 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 TD (15.7%), whereas EOS changes were more attributed to TN (21.8%). A higher response of the SOS to TD was found in more urbanized areas with higher artificial lights, while the sensitivity of the EOS to TN 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.