A Novel Role of Biodiversity in Ecosystem Service: Biochar Produced from Multiple Invasive Species Improves Remediation of Cadmium-Contaminated Soils

Abstract

Biodiversity commonly contributes to ecosystem functioning and provides ecosystem services. Biochar application is frequently used to remediate soils contaminated with heavy metals. As many invasive plant species can quickly form huge amounts of biomass, they are potentially useful for producing biochar for remediating contaminated soils. However, it remains untested whether invasive species richness contributes to biochar-mediated soil remediation. We applied single biochar made from each of six invasive plant species and biochar mixtures (i.e., mixtures of biochar derived from 2, 3, and 6 invasive plant species) to soils contaminated with cadmium (Cd), with no biochar application as the control, and then grew native plant communities on these soils. Compared to the control, biochar application significantly decreased the Cd bioavailability in the soils, and this effect increased with increasing invasive species richness involved in the biochar mixtures. Increasing invasive species richness involved in the biochar mixtures significantly increased both the concentration and pool size of Cd in the roots of the native plant community, although it significantly decreased its biomass. The application of biochar mixtures from diverse invasive plant species can promote remediation of soil contaminated with heavy metals. Our findings thus indicate a novel biodiversity ecosystem service: the use of multiple invasive plant species for the production of biochar applied in phytoremediation. As harvesting of invasive species for biochar production may also contribute to their management, this might mitigate two ecological problems at once.

Keywords: biochar diversity, biodiversity effect, cadmium immobilization, heavy metal, invasive species, Soil remediation