Assessment on Ecological Health Effects of Plant Communities in Typical Urban Green Spaces: A Multi-Scale Comparative Study

The eco-health effects of urban green spaces are playing a vital role in mitigating urban environmental stress and promoting residents’ well-being. However, the specific differences and dominant factors influencing these effects across different green space types and plant community structures have not been fully elucidated. This study selected three typical green spaces in Tianfu New District of Chengdu—regional green space, comprehensive park, and specialized park—and focused on four community structures: tree–shrub–herb, tree–herb, tree-only, and herb-only. Multi-scale in situ monitoring was conducted during summer, and a comprehensive index method was employed for evaluation. The results demonstrated that (1) the tree–shrub–herb multi-layered structure exhibited the optimal eco-health function at the community scale, with a PM2.5 reduction rate of 73.86%, a noise reduction rate of 25.13%, and a negative air ion supply rate of up to 396%, significantly outperforming other structures. (2) The overall effect of regional green space (composite index 10.41) at the site scale was significantly higher than that of comprehensive parks (6.42) and specialized parks (5.87), respectively. (3) The eco-health effect increased with the complexity of the community structure, ranking as: tree–shrub–herb > tree-only > tree–herb > herb-only, highlighting the prominent contribution of the tree layer. Plant diversity showed a positive but non-significant trend. In conclusion, this multi-scale comparative study clarifies the differential impacts of green space types and community structures on the eco-health effect. It is recommended that urban planning prioritizes the layout of regional green spaces and adopts the tree–shrub–herb multi-layered structure as the dominant configuration in design in order to enhance the eco-health effect.