Diversity and distribution variation of urban spontaneous vegetation with distinct frequencies along river corridors in a fast-growing city

River corridors are vital to urban ecology, regulating climate and providing habitats for animals. Spontaneous plants naturally colonize various spaces therein, where they play important roles. Previous studies have explored many factors driving spontaneous plant diversity at the city scale and in specific habitats. However, we lack a holistic understanding of the diversity and distribution of variation of spontaneous vegetation that directly re-flects the effects of urbanization. We conducted a field study of 1250 sample plots along river corridors in Chengdu, a fast-growing city in China, and the spontaneous plants in fifteen microhabitat types were surveyed. Diversity and distribution patterns were examined for species with distinct dispersal abilities. There was a far greater richness of occasional species compared to dominant and common species, but occasional species were markedly less abundant. Vacant lots and natural riverbanks harbored the most species, but revetment walls and lawns also supported a considerable number of species, especially in the city center. Species diversity among different urban areas was strongly related to microhabitat conditions. The proportions of dominant, common, and occasional species varied among communities. In communities on vacant lots of less urbanized areas, the richness of dominant species was greater, whereas in green spaces created by planted vegetation, occasional species were more diverse. Green space microenvironments are hospitable to some rare species. Urbanization and microhabitats have co-effects and thus ultimately determine diversity and distribution patterns. Such pat-terns, if linked to ecological and ornamental value, can provide a new perspective and nature-based solutions to urban rewilding and landscape design.

Automated summary

River corridors are essential for urban ecosystems, playing a crucial role in regulating climate and providing habitats for animals. Spontaneous plants naturally colonize these corridors and have important ecological functions. However, our understanding of the diversity and distribution of spontaneous vegetation, reflecting the effects of urbanization, is limited. In this study, we surveyed the spontaneous plants in fifteen microhabitat types along river corridors in Chengdu, China, and found that species diversity was strongly influenced by microhabitat conditions. Urbanization and microhabitats together determine the diversity and distribution patterns of spontaneous vegetation, offering insights into urban rewilding and landscape design.