Managing urban park landscape patterns to balance plant diversity and biotic homogenization across life forms: A case study of Chaoyang District, Beijing

Biodiversity loss and the homogenization of plant communities are commonly observed in urbanized environments, highlighting the importance of maintaining plant diversity and compositional distinctness in urban green spaces. Urban parks are key refugia for plants, yet it remains unclear how their landscape patterns can be configured to simultaneously enhance species richness and reduce compositional homogenization across different plant life forms. Based on transect surveys of 820 plant species in 31 urban parks in Chaoyang District, Beijing, we combined multi-life-form analyses with a data-driven landscape framework to (i) identify the landscape metrics that best explain variation in plant richness and community composition, and (ii) quantify the trade-offs involved in reconciling their divergent requirements. We found consistently high levels of biotic homogenization across all plant types (all species, trees, shrubs, herbs and vines). Seventeen key landscape metrics were selected as important predictors of richness and composition, among which the interspersion and juxtaposition index provided particularly clear ecological interpretation. Higher morphological complexity of water bodies was associated with lower species richness, which may partly reflect shoreline hardening or reduced riparian habitat quality, whereas higher patch numbers of both green space and water generally promoted species richness and compositional distinctness. However, patch-number adjustments should not simply aim for maximization, but may instead follow a conceptual "peak-shaving and gap-filling" heuristic to balance additional patch creation with reduced redundancy in landscape configurations. For parks lacking water bodies, introducing water features may be considered where hydrologically and ecologically feasible, particularly when designed with naturalized shorelines to support plant richness and compositional distinctness. Our results provide a conceptual and data-driven framework for targeting landscape pattern adjustments in urban parks to promote plant diversity while alleviating biotic homogenization.