Co-existence between humans and nature: Heritage trees in China's yangtze River region

Abstract

The negative consequences of increased urbanization on native biological and cultural diversity have received considerable research attention. Biological and cultural diversity can be sustained by counteracting various processes of floristic homogenization and by reestablishing connections between humans and nature. However, effective instruments to help people reconnect with nature can be lacking, especially in cities. Green spaces provide cultural, aesthetic, and ecological services and can represent a critical component of native plant diversity in urban environments. We examined the species composition of heritage trees and the tangible and cultural values of these trees in 11 major cities in the Yangtze River basin of China. Our analysis explored the similarities of three arboreal types, namely heritage trees, urban greening components, and natural plant communities. Heritage tree species are diverse, containing 310 recorded species representing 159 genera and 64 families. Their tangible and cultural values are mainly medicinal (221 species), followed by timber (186), culture (134), traditional courtyard planting (131) and food (124). Notable geographical differences in heritage tree species composition identified in our analysis could be explained by cities adopting mostly species native to the locality or province. Heritage tree assemblages were similar in composition to undisturbed natural plant communities, and the two populations experienced comparable progressive decline with geographical distance. Urban greening components indicated negligible decline in similarity beyond the 1000 km threshold, indicating common sharing of exotic species across disparate locations. Heritage tree species associated with notable tangible and cultural values, superior genetic constitution, and adaptation to local growth conditions present suitable candidates for urban planting to improve tree performance and urban biodiversity. Their long history of association with local culture and rich cultural values can be enlisted to strengthen the connections of urban communities to nature and history, and to promote nature conservation within cities. Given increasing biological and biocultural homogenization, especially in urban areas, protecting heritage trees and using them in urban greening can slow this trend and enrich stocks of urban biodiversity.