Taking spontaneous plants as a natural strategy for vegetation restoration in construction and demolition waste landfills: a case study in Suzhou, China

Abstract

Construction and demolition waste (CDW) landfills around the city have caused serious damage to the ecological environment and menaced the public health. Restoration of closed CDW landfills is critical to compensate for the degraded ecosystem and ensure safety in further development and utilization. Vegetation restoration is an essential part of the restoration of CDW landfills, in which the use of spontaneous plants is the foundation of the nature-based strategy. In this study, Fenghuangshan CDW landfill in Suzhou, China, was selected as the research site, and the species composition and diversity of the spontaneous plants were analyzed. Moreover, the types of habitats and growth indexes of 8 species with high frequency and 18 species with medium frequency in the CDW landfill were investigated, and a comprehensive evaluation of growth rate and expansion capacity of the 26 species was conducted. The results showed that, herbs were the main type of the spontaneous plants in the CDW landfill. The species and quantities of the spontaneous plants in the CDW landfill were obviously fewer than those in the surrounding areas of the CDW landfill, and the Shannon-Wiener index and Pielou index of the spontaneous plants were lower compared with the surrounding areas of the CDW landfill. Meanwhile, the differences of dominant families and the distribution of origins, life forms and growth types between these two fields were insignificant. The heliophilous and drought tolerance species were widely distributed in the CDW landfill while the shade-tolerant or hygrophilous species were few. The relatively large comprehensive evaluation indexes of Elymus dahuricus, Daucus carota, Sonchus asper, Geranium carolinianum, Rumex acetosa, Metaplexis japonica, Carex breviculmis, Erigeron canadensis, Trigonotis peduncularis, Lamium amplexicaule reflected their high growth rates and strong expansion capacity, demonstrating their great potentiality in the vegetation restoration of CDW landfills as indispensable components of the nature-based solution.

Keywords: Ecological rehabilitation; Growth evaluation; Habitat diversity in landfills; Plant carbon sequestration; Spontaneous vegetation analysis; Urban ecosystem restoration.