Tree Species Diversity Enhances Urban Forest Resilience Globally

Urban forest resilience is essential for sustaining ecosystem functions in urban areas following extreme climate events. However, there remains a lack of scientifically informed strategies for effectively enhancing urban forest resilience. This study evaluated the influence of tree species diversity (Sd) on urban forest resilience in 388 cities worldwide, using the Global Urban Tree Inventory (GUTI) dataset and satellite-derived vegetation index observations. We found that cities situated in wet climates and characterized by lower levels of urbanization tend to exhibit higher Sd and greater forest resilience. Correlation analysis demonstrated that increasing Sd enhances urban forest resilience while mitigating the long-term rate of resilience decline. We further employed a multivariate regression model to quantify the species diversity effect (ρ) in these 388 cities and developed a machine learning model to predict ρ values using 14 environmental variables. By applying the trained machine learning model to 13,500 cities worldwide, we found that the positive impact of tree species diversity on urban forest resilience is more pronounced in cities located in dry climates and those with higher levels of urbanization, compared to cities in wet climates and those with lower levels of urbanization. Notably, approximately 78% of the 13,500 cities demonstrated strong or medium species diversity effects in enhancing forest resilience. Our findings suggest that incorporating diverse tree species into urban ecological planning is essential for enhancing urban ecosystem resilience and promoting the development of green and sustainable cities, particularly in dry and highly urbanized regions.