The results from the project also aim to inform the tropical O3-plant damage parameterisation in the JULES (Joint UK Land Environment Simulator) land surface model. Using the observed dose response functions from the TropOz measurements, we fit a parameter that reduces the rate of photosynthesis and stomatal conductance at each model time step so that over time the net primary productivity decreases and less carbon is accumulated. The model can then be used to identify areas at high risk from O3 damage, and how O3 damage in the tropics may feedback into impacting global carbon cycles within the Earth system.
Using fully-coupled climate model predictions, we find that by 2100 climate change could cause an additional increase in tropical O3 of up to 15 ppb in areas of high biomass burning.
Preliminary work at the TropOz site has suggested that the rate of productivity loss for fast–growing tropical trees with high stomatal conductance is similar to the most O3-sensitive temperate trees. Inga edulis, a species that is commonly planted to restore land area in the Amazonian arc of deforestation, is among the most sensitive to O3 of the tree species investigated to date. If O3 concentrations reach those predicted for 2100, secondary forests dominated by the Inga genus could risk up to a 20% productivity loss. We therefore highlight that the combination of deforestation, fires and climate change could have severe consequences for tropical forests, forest restoration and thus future climate mitigation.
O3 dose response function of Inga edulis coupled to predicted rise in O3 concentrations across the Amazonian arc of deforestation (Cheesman, Brown et al, unpublished)
TropOz 