EGU22-178
https://doi.org/10.5194/egusphere-egu22-178
EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Nitrogen cycling in forest soils under elevated CO2: response of a key soil nutrient to climate change

Manon Rumeau1, Sami Ullah1, Rob Mackenzie1, Yolima Carillo2, Michaela Reay3, and Fotis Sgouridis3
Manon Rumeau et al.
  • 1University of Birmingham, Geography and Environmental Sciences, United Kingdom of Great Britain – England, Scotland, Wales (mlr094@student.bham.ac.uk)
  • 2Hawkesbury Institute for the Environment (HIE), Western Sydney University, Richmond, Australia
  • 3University of Bristol, Bristol, UK

Forests under elevated atmospheric CO2 concentration as a result of climate change are expected to require more available nitrogen (N) to sustain the enhanced CO2 uptake for photosynthesis and C storage. Therefore, it is essential to evaluate how CO2 fumigation of forests will affect availability of N to trees. Main pathways to sustain the high N demand are increasing biological N fixation (BNF), increasing N turn-over and reducing N losses. The purpose of this research is to explore the effects of elevated CO2 on soil N cycling in a temperate forest under the Birmingham Institute of Forest Research (BIFoR) Free Air Carbon Dioxide Enrichment facility. We hypothesize that under CO2 fertilization, trees will allocate more carbon belowground to enhance microbial activity for increasing N mineralization as well as enhancing BNF to meet N demands. We also hypothesize that the subsequent microbial activity will up-regulate N2O and N2 emissions due to denitrification. BNF by free-living organisms is investigated using the 15N assimilation method. Mineralization and N gas production rates is determined using the 15N pool dilution and 15N-Gas flux method at the same time. Early results are showing trends toward an enhancement of N mineralization and microbial N immobilization rates. However, BNF in the forest floor is hardly detectable more likely because of the high N deposition in the area; therefore, it doesn’t appear to be responsive to CO2 fumigation. This research is expected to help us improve our understanding of the changes and magnitude of nutrient availability and gaseous losses under future climates.

How to cite: Rumeau, M., Ullah, S., Mackenzie, R., Carillo, Y., Reay, M., and Sgouridis, F.: Nitrogen cycling in forest soils under elevated CO2: response of a key soil nutrient to climate change, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-178, https://doi.org/10.5194/egusphere-egu22-178, 2022.