Spontaneous urban vegetation and habitat heterogeneity in Xi'an, China

Plant growth and survival can be challenged by harsh urban conditions. There is little published on the spontaneous vegetation in urban China, but studies in other parts of the world show the persistence of native species in built-up areas, and document ecosystem services provided by spontaneous vegetation. Here we describe spontaneous vegetation in urban Xi'an, in northern central China, and quantify the relationships between species diversity and composition, and environmental variables representing productivity, spatial habitat heterogeneity and disturbance. A total of 95 plant species were recorded belonging to 75 genera and 37 families. Family and species diversity were positively related to soil depth and microhabitat heterogeneity, and negatively related to trampling intensity. Variation in species composition was mainly related to trampling intensity and distance from the city center. Microhabitats were weakly differentiated by species composition, likely because several common generalist species were found throughout the city in a variety of microhabitat types. While some of the most frequently encountered species in the spontaneous vegetation of Xi'an are considered non-native and invasive, some of these may be capable of surviving difficult conditions in revegetation projects and could have some benefits in challenging urban environments.