Spatial variations of soil seed banks in Shanghai’s urban wasteland: A gradient analysis of urbanization effects

Abstract

Urbanization greatly impacts both the diversity of soil seed banks and the spatial dynamics of species. These seed banks, which hold seeds from current and past vegetation, are vital in shaping future plant diversity. They also 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 focused on the soil seed bank of wasteland in Shanghai China, by selecting 24 plots along urban-rural gradients. 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 that in spring and no significant difference was found along urban-rural gradients. A total of 75 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 (i.e. the proportion of annual plant species, small growth type species, exotic species, and dispersal modes), species diversity (i.e. richness and Shannon-Wiener index), and species composition, excepting that marginal significant for autumn 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.