title: Reduced soil water availability did not protect two competing grassland species from the negative effects of increasing background ozone.
abstract: Two common (semi-) natural temperate grassland species, Dactylis glomerata and Ranunculus acris, were grown in competition and exposed to two watering regimes: well-watered (WW, 20-40% v/v) and reduced-watered (RW, 7.5-20% v/v) in combination with eight ozone treatments ranging from pre-industrial to predicted 2100 background levels. For both species there was a significant increase in leaf damage with increasing background ozone concentration. RW had no protective effect against increasing levels of ozone-induced senescence/injury. In high ozone, based on measurements of stomatal conductance, we propose that ozone influx into the leaves was not prevented in the RW treatment, in D. glomerata because stomata were a) more widely open than those in less polluted plants and b) were less responsive to drought. Total seasonal above ground biomass was not significantly altered by increased ozone; however, ozone significantly reduced root biomass in both species to differing amounts depending on watering regime.
authors.affiliation: Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK. sergga@ceh.ac.uk
authors.forename: Serena
authors.initials: S
authors.lastname: Wagg
authors.forename: Gina
authors.initials: G
authors.lastname: Mills
authors.forename: Felicity
authors.initials: F
authors.lastname: Hayes
authors.forename: Sally
authors.initials: S
authors.lastname: Wilkinson
authors.forename: David
authors.initials: D
authors.lastname: Cooper
authors.forename: William J
authors.initials: WJ
authors.lastname: Davies
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D031745:Dactylis / Q000502:physiology*; D055864:Droughts; D010126:Ozone / Q000633:toxicity*; D031947:Ranunculus / Q000502:physiology*; D013312:Stress, Physiological
chemical_list: D000393:Air Pollutants; D010126:Ozone