Interactive effects of drought and elevated atmospheric CO2 on tree nutrient uptake and carbon capture

The rising atmospheric carbon (C) dioxide (eCO2) concentration is predicted to increase C capture in plants. In contrast, the frequent episodes of drought are expected to reduce the nutrient availability in soils and reduce the C capture in plants. In addition to aboveground modifications, plant roots mediate nutrient availability in soil by changing root architecture, and exuding C-rich metabolites to enhance microbial activity, whereas microbes in the rhizosphere produce specific enzymes for the mineralization of organic matter for needed nutrient supplies. It is unclear whether the eCO2 compensation of drought stress via enhanced water use efficiency may help sustain C capture in forests under future climates. This project proposal directly addresses this uncertainty around the interactive impacts of eCO2 and drought on Quercus robur whole plant-soil system nutrient acquisition strategies, to enable robust and realistic assessment of the role of forests in mitigating climate change.