Spatial variations of soil seed banks in Shanghai's urban wasteland: a gradient analysis of urbanization effects.

Urbanization greatly impacts both the diversity of soil seed banks and the spatial dynamics of species. These seed banks serve as a window into the ecological history and potential for recovery in urban wastelands, which are continually evolving due to urbanization. In this study, we selected 24 plots along urban-rural gradients in Shanghai, China. Soil samples were collected from each plot for seed bank germination experiment in both spring and autumn. We tested whether the seed density, species diversity, and composition of soil seed banks in wasteland varied along an urban-rural gradient. The results showed that seed density was higher in autumn than in spring and no significant difference was found along urban-rural gradients. A total of 74 species, belonging to 26 families and 69 genera, was recorded in soil seed banks, in which annuals were the dominant life form and autochory was the dominant dispersal model. The proportion of exotic species was nearly 40%. There is no significant difference along urban-rural gradients for functional composition, species diversity, and species composition, excepting that marginal significant for autumn Shannon-Wiener index and species composition among urban-rural gradients. The relative homogeneity in the seed bank across urban-rural gradients may primarily be due to the young age of the wastelands.