Species composition but not interspecific facilitation enhances zinc and selenium uptake in multispecies grasslands

Abstract

Abstract Aims To understand the variations among grassland species in their ability to take up zinc (Zn) and selenium (Se) when cultivated as monocultures and to assess the effect of species richness on Zn and Se uptake. Additionally, to examine whether interspecific facilitation or species composition of the mixtures contributes to the potential increase in Zn and Se uptake in mixtures. Methods We conducted a grassland diversity experiment at both pot and field scales. In the greenhouse pot experiment, three grasses, four legumes and five forb species were grown as monocultures and mixtures along a species richness gradient. In the field experiment, we compared a monoculture of Lolium perenne sward with two multispecies mixtures (comprising grasses, legumes, and forbs). At harvest, Zn and Se uptake values were determined for all the monocultures and mixtures in both experiments. Results The capacity of the monoculture species to take up Zn and Se varied significantly in the pot experiment. Zinc and Se uptake increased with increasing species richness (P < 0.05). Higher Zn and Se uptake in the multispecies mixtures was primarily due to the large aboveground biomass production and/or high tissue Zn and Se concentration of some of the component species in the mixtures. However, there was insufficient evidence supporting interspecific facilitation. Conclusion To optimize Zn and Se uptake by multispecies mixtures, it is suggested that the choice of forage species should be based on biomass production potential as well as Zn and Se concentrations of the component species in the mixture.