Environmental Limitations to O3 Uptake - Some Key Results from Young Trees Growing at Elevated Co2 Concentrations |
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| Authors: | MSJ Broadmeadow J Heath TJ Randle |
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| Institution: | 2. Forest Research, Alice Holt Lodge, Wrecclesham, Farnham, Surrey, GU10 4LH, UK
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| Abstract: | Elevated carbon dioxide concentrations and limited water supply have been shown to reduce the impact of ozone pollution on the growth and physiology of Quercus petraea in a long-term factorial experiment. These responses can be explained by observed reductions in stomatal conductance, and thus potential ozone exposure of 28% and 40% for CO2 and drought treatments respectively. However, parameterisation of a stomatal conductance model for Quercus robur and Fagus sylvatica grown under ambient and elevated CO2 concentrations in a separate experiment has demonstrated that elevated CO2 also reduces the responsiveness of stomata to both saturation deficit (LAVPD) and soil moisture deficit (ψ) in beech, and to a lesser extent, in oak. Season-long model simulations of ozone fluxes suggest that LAVPD and ψ conductance parameters derived at ambient CO2 concentrations will lead to these fluxes being underestimated by 24% and 2% for beech and oak respectively at 615 ppm CO2. |
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