Tree Species Diversity in Urban and Peri-urban Forests Significantly Improved Human Wellbeing in Karlsruhe, southwest Germany

Green spaces and trees are vital components for enhancing human well-being in cities. While the significance of urban greenery for human health is well recognized, the impact of urban biodiversity on well-being remains insufficiently explored in terms of quantitative evidence. This study investigated the relationship between tree genus diversity, perceived urban biodiversity, and the subjective well-being of urban residents in Karlsruhe, Germany. An online questionnaire based on mapping involving 302 participants examined well-being locations and perceptions of biodiversity. Using remote sensing and ground data, tree genus diversity was assessed for nine genera. A novel approach that spatially correlates societal mapping results with tree genus cover maps revealed a distinct preference for green spaces within the constructed urban environment. A significant association was found between the perceived biodiversity of urban green spaces and subjective well-being. The extent of tree cover, the presence of large trees, and the perceived species diversity beyond tree genera all positively contribute to the well-being of the urban population. In contrast, the perceived untidiness of urban areas negatively affects residents’ well-being. This should be considered in future research and the design of urban green spaces. To our knowledge, this is one of the first studies worldwide that has quantified and mapped the compositional diversity of urban and peri-urban forests, perceived biodiversity, and human well-being.