A stronger advance of urban spring vegetation phenology narrows vegetation productivity difference between urban settings and natural environments

Climate change is posing dramatic effects on terrestrial vegetation dynamics. The links between vegetation phenology or vegetation activity (growth) and climate change have been widely reported, yet, less is known about the impacts of phenological shifts on vegetation growth. Urban settings characterized by urban heat island and CO2 dome are often used as ideal natural laboratories to understand how vegetation responds to global climate change. Here we assessed the impacts of phenology changes on vegetation growth in China using satellite phenology metrics and gross primary production (GPP) data from 2003 to 2018 and urban-natural contrast analysis. Compared with natural environments, phenological metrics (e.g., start/end of growing season (SOS/EOS), and the length of growing season (GSL), etc.) were observed to change more dramatically in urban environments. Furthermore, we found that GPP in both settings in-creased over time but with a higher increment in the urban environments, and the urban-natural vegetation produc-tivity gap had been diminishing at a rate of 16.9 +/- 6.76 g C m-2 y-1. The narrowing of the urban-natural GPP difference over time can be attributed to a more advanced SOS and extended GSL in urban settings than their natural counterparts, particularly SOS shift. These findings suggested that the distinct urban phenological shifts would become increasingly important in offsetting the loss of vegetation productivity induced by urbanization.

Automated summary

Climate change has significant impacts on terrestrial vegetation dynamics. This study assessed the effects of phenology changes on vegetation growth in China, using satellite phenology metrics and gross primary production (GPP) data. The findings showed that the phenological metrics changed more dramatically in urban environments compared to natural environments. The narrowing of the urban-natural GPP difference over time can be attributed to the advanced start of growing season (SOS) and extended length of growing season (GSL) in urban settings.