EGU22-12003
https://doi.org/10.5194/egusphere-egu22-12003
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Temporal and spatial effects of elevated CO2 on greenhouse gas fluxes from tree stems in an upland temperate forest

Josep Barba1,2, Giulio Curioni2, and Vincent Gauci2
Josep Barba et al.
  • 1CREAF, Bellaterra, Spain (j.barba@creaf.uab.cat)
  • 2BIFoR, University of Birmingham, UK

Tree stems emit CO2 and can exchange CH4 with the atmosphere (either emitting or uptaking), with a significant contribution to the C budgets from local to regional scales. However, there is still a need to better understand the spatial and temporal variability of stem CO2 and CH4 fluxes to quantify the role of vegetation on the C cycle and how these fluxes will behave under future environmental conditions such as atmospheric elevated CO2. An increment of atmospheric CO2 concentrations might result in higher photosynthetic rates, which would spin the C cycle in the trees, potentially increasing stem CO2 emissions due to higher stem respiration and higher soil-derived CO2 contribution. Higher photosynthetic rates might also stimulate fine roots exudation, which could stimulate methanotrophic or methanogenic communities. Additionally, elevated CO2 would increase water use efficiency at the leaf level, reducing the amount of water transpired, and potentially increasing soil moisture, which would favour conditions for CH4 production. In this study, we present one year of monthly measurements of stem CO2 and CH4 fluxes from mature oaks (Quercus robur) growing under elevated CO2 (~150 ppm above atmospheric concentrations) and ambient conditions, in a second-generation FACE experiment (Free Air CO2 Enrichment; BIFoR-FACE UK). Trees growing under ambient conditions emitted 76% more CO2 than those under elevated atmospheric CO2, which was not what we hypothesized. Despite stem CH4 fluxes have been reported in multiple upland ecosystems for lots of tree species, our preliminary results did not show clear evidence of CH4 stem fluxes (emissions or uptake) for the oaks at our study site. Similar measurements in other FACE experiments are needed to determine if our results on the effect of elevated CO2 on stem CO2 and CH4 fluxes could be extrapolated to other ecosystems and species. 

How to cite: Barba, J., Curioni, G., and Gauci, V.: Temporal and spatial effects of elevated CO2 on greenhouse gas fluxes from tree stems in an upland temperate forest, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12003, https://doi.org/10.5194/egusphere-egu22-12003, 2022.