Urban vegetation productivity under climate change and increasing urbanization: Insights from both urban-rural comparison and trend analysis for global cities

Abstract

Under increasing urbanization and global climate change, the coverage and growth state of urban vegetation have experienced profound changes, but how they affect urban vegetation productivity remains unclear. Here, we used satellite-derived near-infrared reflectance of vegetation (NIRv, a proxy of gross primary productivity) and global long-term 30 m landcover datasets to examine the spatial differences and temporal dynamics of urban vegetation cover and productivity for 1782 cities worldwide. Spatially, urban vegetation productivity is prevalently higher than that in nearby rural backgrounds (+31.77 % ± 49.55 %), with greater enhancement ratio in highly urbanized blocks. From the temporal perspective, urban vegetation productivity generally increased (1.07 % ± 0.96 % per year) despite substantial loss of vegetation cover (–0.51 ± 0.42 percentage points per year) during 2001–2020. Globally, climate changes-dominated background changes made greater contributions (0.71 % ± 0.75 % per year) to the increasing urban vegetation productivity than urbanization-induced local changes (0.47 % ± 0.87 % per year). Notable differences in the local changes of vegetation productivity were observed within cities, as new urban areas had greater increasing trends than old urban areas. The local changes in urban vegetation productivity are primarily determined by the intensity of urbanization and its changes, further modulated by city’s climatic and socioeconomic conditions. By separating the effects of vegetation cover and productivity changes on observed vegetation dynamics, our findings deepen the understanding of urban vegetation changes and provide valuable reference for building greener cities.