Abstract
BackgroundPhytoextraction is an environmentally acceptable and inexpensive technique for mine tailing rehabilitation that uses metallophyte plants. These plants reduce the soil trace metal contents to environmentally acceptable levels by accumulating trace metals. Recently, whether more trace metals can be removed by species-rich communities of these plants received great attention, as species richness has been reported having positive effects on ecosystem functions. However, how the species richness affects trace metals removal of plant communities of mine tailing is rarely known.Methodology/Principal FindingsWe examined the effects of species richness on soil trace metal removal in both natural and experimental plant communities. The root lengths and stem heights of each plant species were measured in order to calculate the functional diversity indices. Our results showed that trace metal (Cu, Cd, Pb and Zn) concentrations in mine tailing soil declined as species richness increased in both the natural and experimental plant communities. Species richness, rather than functional diversity, positively affected the mineralomass of the experimental plant communities. The intensity of plant-plant facilitation increased with the species richness of experimental communities. Due to the incremental role of plant-plant facilitation, most of the species had higher biomasses, higher trace metal concentrations in their plant tissues and lower malondialdehyde concentrations in their leaves. Consequently, the positive effects of species richness on mineralomass were mostly attributable to facilitation among plants.Conclusions/SignificanceOur results provide clear evidence that, due to plant-plant facilitation, species richness positively affects the removal of trace metals from mine tailing soil through phytoextraction and provides further information on diversity conservation and environmental remediation in a mine tailing environment.
Highlights
Research into understanding how species diversity affects ecosystem function has increased over the past two decades [1,2]
In the natural plant communities growing on the Huangyan Pb/Zn mine tailings, soil trace metal (Cu, Cd, Pb and Zn) concentrations were negatively correlated with species richness (Fig. 1)
FDQ (r = 0.430, n = 15, P = 0.110), CWMroot (r = 0.494, n = 15, P = 0.061) and CWMstem (r = 0.485, n = 15, P = 0.067) had no significant relationship with biomass. These results suggested that the significant effect of actual species richness on mineralomass was probably closely linked to biomass production
Summary
Research into understanding how species diversity affects ecosystem function has increased over the past two decades [1,2]. Phytoextraction is an environmentally friendly and inexpensive technique for mine tailing rehabilitation that uses metallophyte plants. They accumulate trace metals through their roots, which reduces trace metal content in the soil to environmentally accepted levels [11]. Phytoextraction is an environmentally acceptable and inexpensive technique for mine tailing rehabilitation that uses metallophyte plants These plants reduce the soil trace metal contents to environmentally acceptable levels by accumulating trace metals. Whether more trace metals can be removed by species-rich communities of these plants received great attention, as species richness has been reported having positive effects on ecosystem functions. How the species richness affects trace metals removal of plant communities of mine tailing is rarely known
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