Abstract
Anthropogenic activities have weakened the invasion of ruderals and increased the number of non-native species in urban areas. Ruderals are an important component of urban plant diversity and are of great significance to the sustainable development of urban green space. We used the tessellation⁻randomized plot method to examine the composition and biodiversity of ruderal species among urban land use types (LUTs) in the built-up areas of Beijing. Soil samples from the surface to a depth of 10 cm were taken from each site to examine the impact of soil characteristics on ruderal species diversity. Results showed that a total of 120 ruderal species were observed, including 71 native and 49 non-native species. Among them, 90% were identified as Cosmopolitan. Native species accounted for the majority of ruderals across all the eight LUTs. Institutional, residential, and woodlot areas with coarser management had higher ruderal species richness than did commercial areas and roadside lawns. Allergenic species showed the highest proportions in municipal parks, and invasive species accounted for 20% of all ruderal species. Ruderal species diversity was related to distance from the urban center, pruning intensity, and soil characteristics. These results suggest that with ruderals playing an important role in urban grass species diversity, there is tremendous potential for more native species in Beijing lawns, which would contribute substantially to increasing the ecological system's functional benefits. Ruderal species accustomed to the causal processes and environmental conditions of different LUTs should be used and conserved properly to improve the harsh conditions of different LUTs and to sustain ecosystem health.