Does the stress tolerance of mixed grassland communities change in a future climate? A test with heavy metal stress (zinc pollution)

Will species that are sensitive/tolerant to Zn pollution still have the same sensitivity/tolerance in a future climate? To answer this question we analysed the response of constructed grassland communities to five levels of zinc (Zn) supply, ranging from 0 to 354 mg Zn kg−1 dry soil, under a current climate and a future climate (elevated CO2 and warming). Zn concentrations increased in roots and shoots with Zn addition but this increase did not differ between climates. Light-saturated net CO2 assimilation rate (Asat) of the species, on the other hand, responded differently to Zn addition depending on climate. Still, current and future climate communities have comparable biomass responses to Zn, i.e., no change in root biomass and a 13% decrease of above-ground biomass. Provided that the different response of Asat in a future climate will not compromise productivity and survival on the long term, sensitivity is not altered by climate change.

► We exposed constructed grassland communities to Zn addition in a current and a future climate.
► Zn uptake did not differ between the climates.
► Although Asat was more responsive to Zn in future climate, climate did not alter biomass responses.
► If this response remains on the long term, climate change will not alter sensitivity.