Ozone effects in a drier climate: implications for stomatal fluxes of reduced stomatal sensitivity to soil drying in a typical grassland species

Hayes, Felicity; Wagg, Serena; Mills, Gina; Wilkinson, Sally; Davies, William. 2012 Ozone effects in a drier climate: implications for stomatal fluxes of reduced stomatal sensitivity to soil drying in a typical grassland species. Global Change Biology, 18 (3). 948-959. 10.1111/j.1365-2486.2011.02613.x

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Abstract/Summary

The widely distributed temperate grassland species Dactylis glomerata was grown in competition with Ranunculus acris at two different watering regimes and exposed for 20 weeks to eight ozone treatments with mean concentrations ranging from 16.2 to 89.5 ppb, representing pre-industrial to predicted post-2100 ozone climates. Measurements of stomatal conductance were used to parameterize ozone flux models for D. glomerata. For the first time, a modification was made to the standard flux model to account for the observed decrease in sensitivity of stomatal conductance to reduced water availability with increasing ozone. Comparison of calculated cumulative ozone flux between the two versions of the model demonstrated that exclusion of the ozone effect on stomatal conductance in the standard flux model led to a large underestimation of ozone fluxes at mid- to high-ozone concentrations. For example, at a mean ozone concentration of 55 ppb (as predicted for many temperate areas in the next few decades), the standard flux model underestimated ozone fluxes in D. glomerata by 30–40% under reduced water availability. Although the modified flux model does not markedly change the flux-based critical level for D. glomerata, this study indicates that use of the standard flux model to quantify the risk of ozone damage to a widely distributed grassland species such as D. glomerata in areas where high ozone concentrations and reduced soil moisture coincide could lead to an underestimation of effects. Thus, this study has shown that under predicted future climate change and ozone scenarios, ozone effects on vegetation may be even greater than previously predicted in the drier areas of the world.

Item Type:	Article
Identification Number/DOI:	10.1111/j.1365-2486.2011.02613.x
Programmes:	CEH Topics & Objectives 2009 onwards > Biodiversity CEH Topics & Objectives 2009 onwards > Biogeochemistry
CEH Sections:	Emmett
ISSN:	1354-1013
Additional Keywords:	background ozone, climate change, Dactylis glomerata, ozone flux, soil moisture, stomata, stomatal conductance
NORA Subject Terms:	Ecology and Environment Atmospheric Sciences Botany
Date made live:	31 Aug 2012 13:50
URI:	http://nora.nerc.ac.uk/id/eprint/19415

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