Spatial patterns and influencing factors of ancient trees in a highly urbanized megacity: evidence from Shanghai

• A comprehensive analysis of 2,833 ancient trees and their successors in Shanghai • Spatial analyses link tree clusters to cultural origins, site type and religion • Survival hinges on lifespan and ecological resilience for ancient species prediction • Identifying tree species with higher potential to become future ancient trees Ancient trees are the invaluable natural and cultural treasures, crucial for maintaining biodiversity. However, at the city scale, the spatial patterns of ancient trees and the mechanisms underlying their long-term persistence remain insufficiently quantified, particularly in highly urbanized megacities. This study focuses on ancient trees and their successor resources in Shanghai, aiming to characterize their species diversity, spatial distribution patterns, and key driving factors. Spatial analyses were conducted using Geographic Information System (GIS) techniques, including spatial autocorrelation and inequality analyses, while a random forest model was employed to evaluate the relative importance of species-level attributes associated with long-term survival. The findings revealed that a total of 2,833 ancient trees and their successor resources were documented. Overall, their spatial distribution exhibited a clustering pattern, with a more concentrated distribution in the birthplace of Shanghai's historical and cultural heritage. The spatial patterns reflected the combined influences of environmental conditions, historical land use, cultural heritage, and site characteristics. Model results further indicated that potential lifespan and ecological adaptability and resistance were the most influential factors shaping the likelihood of trees persisting for over a century, with Gini importance scores of 21.28 and 18.99, respectively. These findings provide a quantitative basis for identifying tree species with higher potential to become future ancient trees and offer practical insights for the conservation, management, and sustainable planning of ancient tree resources in cities.