Net root growth and nutrient acquisition in response to predicted climate change in two contrasting heathland species

Background and aims Accurate predictions of nutrient acquisition by plant roots and mycorrhizas are critical in modelling plant responses to climate change. Methods We conducted a field experiment with the aim to investigate root nutrient uptake in a future climate and studied root production by ingrowth cores, mycorrhizal colonization, and fine root N and P uptake by root assay of Deschampsia flexuosa and Calluna vulgaris . Results Net root growth increased under elevated CO 2 , warming and drought, with additive effects among the factors. Arbuscular mycorrhizal colonization increased in response to elevated CO 2 , while ericoid mycorrhizal colonization was unchanged. The uptake of N and P was not increased proportionally with root growth after 5 years of treatment. Conclusions While aboveground biomass was unchanged, the root growth was increased under elevated CO 2 . The results suggest that plant production may be limited by N (but not P) when exposed to elevated CO 2 . The species-specific response to the treatments suggests different sensitivity to global change factors, which could result in changed plant competitive interactions and belowground nutrient pool sizes in response to future climate change.