Biomass and phytoextraction potential of three ornamental shrub species tested over three years on a large-scale experimental site in Shanghai, China

Abstract

Issues related to environmental degradation are of increasing concern worldwide. In urban Shanghai, many plant species used for ornamental purposes grow under harsh conditions yet show good resistance to pollution. Twelve shrub species were tested in a previous study to evaluate their capacity to tolerate and absorb inorganic contaminants. Among these, Hibiscus mutabilis and H. hamabo and Senna corymbosa, presented good performance and were tested over three growing seasons in a large experimental design (2000 m²) where the soil was spiked with salts of Cu, Pb, or Zn. Each year of the study, all plants were cut and biomass was harvested and analyzed. Despite the relatively high concentration of metals in plots, no signs of toxicity were observed. Concentrations of metals in root tissues were generally much higher than those found in aerial parts. The bioconcentration factor values were generally very low, but the high biomass yield produced by H. mutabilis led to significant removal of Cu and Zn. No difference in the quantity of Pb extracted was found between species. As these plants respond well to coppicing, it may be possible to gradually eliminate contaminants from soils. Their use can also embellish the landscape while generating many other ecological services.

Keywords:

• Contaminated soils
• Hibiscus sp.
• phytoextraction
• Senna corymbosa
• trace elements (TE)
• urban conditions

Acknowledgements

Our thanks to Stéphane Daigle for assistance with statistical analysis, to Zhang Guowei for his technical assistance, and to Karen Grislis for her critical review of the manuscript. We would also like to thank the Shanghai Chenshan Botanical Garden for the implementation of the study site and providing us access to it.

Additional information

Funding

Shanghai Administration Bureau of Landscape and City Appearance (Grant No. G152426, G182420), the Shanghai Committee of Science and Technology, China (Grant No. 18DZ1204700, 18DZ1204701) and the Quebec Research Fund - Nature and Technology (Grant No. 211259).