Plant species composition in green spaces within the built-up areas of Beijing,China

Plant species composition is a critical issue in ecological research. Studies on the characteristics of plant species composition in the built-up areas, however, are hampered by a lack of basic field-based investigation. In this article, the plant species composition in the built-up areas of Beijing, China, is investigated using abundant field observations. The origin of species, chorological spectra, life forms and plant communities were determined. The characteristic species in each type of green space were determined by k-means classification, and urban plant communities were identified by two-way indicator species analysis (TWINSPAN). Plant species composition in the built-up areas was further compared with that in natural mountain floras in Beijing to reveal the differences in life form composition and chorological spectra, and the coincidence of species in the two communities. A total of 618 plant species belonging to 349 genera and 103 families were identified. Our results revealed wide chorological spectra with trees dominated by deciduous species. Although native plant species were widely distributed, 53% of the plant species were aliens, among which 67% were introduced from America and other Asian countries. Furthermore, the characteristics of the plant species composition in the built-up areas are significantly different from those of the natural habitats. Our results highlight the dramatic changes in characteristics of plant species composition in the built-up area of Beijing. Several suggestions are proposed to increase the diversity of native species through the planning and management of green spaces.