Relationships between multi-scale factors, plant and pollinator diversity, and composition of park lawns and other herbaceous vegetation in a fast growing megacity of China

•Lawns as habitats for plants and pollinators in a Chinese megacity were studied.•Lower-input management and more green areas around urban lawns increase floristic diversity.•Lawns and perennial meadows are dominated by exotic and even invasive species.•Flowering plant species richness is determinant for pollinator species diversity.•The flowers of some native forbs are attractive to wild bees and hoverflies.