Abstract
The increasing number of contaminated sites worldwide calls for sustainable remediation, such as phytoremediation, in which plants are used to decontaminate soils. We hypothesized that better anchoring phytoremediation in plant ecophysiology has the potential to drastically improve its predictability. In this study, we explored how the community composition, diversity and coppicing of willow plantations, influenced phytoremediation services in a four-year field trial. We also evaluated how community-level plant functional traits might be used as predictors of phytoremediation services, which would be a promising avenue for plant selection in phytoremediation. We found no consistent impact of neither willow diversity nor coppicing on phytoremediation services directly. These services were rather explained by willow traits related to resource economics and management strategy along the plant “fast–slow” continuum. We also found greater belowground investments to promote plant bioconcentration and soil decontamination. These traits–services correlations were consistent for several trace elements investigated, suggesting high generalizability among contaminants. Overall, our study provides evidence, even using a short taxonomic (and thus functional) plant gradient, that traits can be used as predictors for phytoremediation efficiency for a broad variety of contaminants. This suggests that a trait-based approach has great potential to develop predictive plant selection strategies in phytoremediation trials, through a better rooting of applied sciences in fundamental plant ecophysiology.
Highlights
Soil contamination represents a risk for ecosystems and human health [1]
Our findings show that Organic matter (OM) reduced bioconcentration and phytostabilization, which could be explained by the efficient trace elements (TE) adsorption on exchange sites of soil OM, some of which was added at the beginning of our experiment in the form of compost
Phytoextraction and phytostabilization of willows can be predicted by the plant economic spectrum, which represents growth strategies and plantation maturity
Summary
Soil contamination represents a risk for ecosystems and human health [1]. Worldwide urbanization and industrialization are rapidly increasing the number of contaminated brownfields, which would benefit from sustainable remediation approaches [2]. Given the wide variation in plants’ abilities to tolerate, accumulate, immobilize or degrade contaminants [4], one of the main challenges of phytoremediation remains identifying and predicting the best candidates or combinations of plants to perform key remediation services. Willows (Salix spp.) are often used for brownfield remediation because of their efficiency and versatility, as well as their capacity to establish on sites with harsh conditions [5]. They accumulate trace elements (TE), grow quickly, produce large amounts of biomass, tolerate a wide variety of stressors and resprout quickly after copping (aboveground biomass harvest) [6,7]. Using a diversity of willow species or cultivars may lead to the delivery of complementary services, especially under mixed contamination, as is often the case on brownfields [13,14]
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