Direct and indirect impacts of urbanization on vegetation growth across the world's cities

Urban environments, regarded as harbingers of future global change, may exert positive or negative impacts on urban vegetation growth. Because of limited ground-based experiments, the responses of vegetation to urbanization and its associated controlling factors at the global scale remain poorly understood. Here, we use satellite observations from 2001 to 2018 to quantify direct and indirect impacts of urbanization on vegetation growth in 672 worldwide cities. After controlling for the negative direct impact of urbanization on vegetation growth, we find a widespread positive indirect effect that has been increasing over time. These indirect effects depend on urban development intensity, population density, and background climate, with more pronounced positive effects in cities with cold and arid environments. We further show that vegetation responses to urbanization are modulated by a cities' developmental status. Our findings have important implications for understanding urbanization-induced impacts on vegetation and future sustainable urban development.

Automated summary

Based on satellite observations from 2001 to 2018, this study examines the direct and indirect impacts of urbanization on vegetation growth in 672 cities worldwide. It finds a widespread positive indirect effect of urbanization on vegetation growth, which has been increasing over time. These indirect effects are influenced by urban development intensity, population density, and background climate, with higher positive effects in cities with cold and arid environments. The study also suggests that the vegetation responses to urbanization are modulated by a cities' developmental status.