The post-effects of landscape practices on spontaneous plants in urban parks

Urban ecosystems, initially shaped by landscape practices (planning, design, construction and management of outdoor environments), continue to evolve under these influences. This dynamic process results in long-term ecological impacts and fosters complex biodiversity patterns, characterized by the co-existence of both cultivated and spontaneous species. While current literature predominantly focuses on broader land use/cover patterns and changes, there is insufficient attention to the indirect and secondary impacts on urban biodiversity that follow initial landscape practices. Using 38 urban parks in a high-density of built-up city, Shanghai, China as an example, this study examines how specific landscape practices, leave a lasting imprint on urban flora, particularly spontaneous plant species that thrive post-intervention. To better understand the impacts of different data types (e.g. compositional data), a suite of Mantel tests, Canonical Correspondence Analysis and Variance Partitioning Analysis was used at two design scales: the whole park and the finer, site scale. This study identifies 211 spontaneous plant species in 169 genera from 82 families. At the whole park scale, park area had the most significant positive correlation with spontaneous plant diversity, whereas patch density primarily influenced spontaneous plant composition. The study shows the crucial role of the “natural” landscape design style in fostering spontaneous plant diversity. At the site scale, factors related to water conditions, such as vertical stratification of the community, low-lying and canopy cover percentage, significantly impact the diversity and composition of spontaneous plant species. Importantly, our study reveals that cultivated plant species significantly influence the diversity of spontaneous plant assemblages, suggesting positive interactions at the whole park scale but shifting to negative interplays at the site scale. Our work facilitates a better understanding of the forces that (re)shape and determine the structural and functional attributes of an urban novel ecosystem and can inform landscape design to optimize urban biodiversity conservation.