Enhanced nitrogen deposition exacerbates the negative effect of increasing background ozone in Dactylis glomerata, but not Ranunculus acris |
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Authors: | Wyness Kirsten Mills Gina Jones Laurence Barnes Jeremy D Jones Davey L |
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Institution: | a Centre for Ecology and Hydrology (CEH), Environment Centre Wales, Deiniol Road, Bangor LL57 2UW, UK b Newcastle Institute for Research on the Environment and Sustainability [NIRES], Devonshire Building, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK c School of the Environment & Natural Resources, Bangor University, Bangor, Gwynedd LL57 2UW, UK |
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Abstract: | The combined impacts of simulated increased nitrogen (N) deposition (75 kg N ha−1 yr−1) and increasing background ozone (O3) were studied using two mesotrophic grassland species (Dactylis glomerata and Ranunculus acris) in solardomes, by means of eight O3 treatments ranging from 15.5 ppb to 92.7 ppb (24 h average mean). A-Ci curves were constructed for each species to gauge effects on photosynthetic efficiency and capacity, and effects on biomass partitioning were determined after 14 weeks. Increasing the background concentration of O3 reduced the healthy above ground and root biomass of both species, and increased senesced biomass. N fertilisation increased biomass production in D. glomerata, and a significantly greater than additive effect of O3 and N on root biomass was evident. In contrast, R. acris biomass was not affected by high N. The study shows the combined effects of these pollutants have differential implications for carbon allocation patterns in common grassland species. |
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Keywords: | Ozone Nitrogen Root:shoot ratio Grassland Carbon allocation |
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