| 1. |
- Karlsson, Per Erik, 1957, et al.
(författare)
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A cumulative ozone uptake-response relationship for the growth of Norway spruce saplings
- 2004
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 128:3, s. 405-417
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Tidskriftsartikel (refereegranskat)abstract
- Norway spruce saplings [Picea abies (L.) Karst.] were exposed during four growing seasons to different ozone treatments in open-top chambers: charcoal filtered air (CF), non-filtered air (NF) and non-filtered air with extra ozone (NF+, 1.4xambient concentrations). The CF and NF + ozone treatments were combined with phosphorous deficiency and drought stress treatments. The total biomass of the trees was harvested at different intervals during the experimental period. The ozone uptake to current-year needles of the Norway spruce saplings was estimated using a multiplicative stomatal conductance simulation model. There was a highly significant correlation between the reduction of total biomass and the estimated cumulative ozone uptake, which did not vary when different thresholds were applied for the rate of ozone uptake. The reduction of the total biomass was estimated to 1 per 10 mmol m(-2) cumulated ozone uptake, on a projected needle area basis. (C) 2003 Elsevier Ltd. All rights reserved.
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| 2. |
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| 3. |
- Piikki, Kristin, 1975, et al.
(författare)
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The impact of tropospheric O3 on leaf number duration and tuber yield of the potato (Solanum tuberosum L.) cultivars Bintje and Kardal
- 2004
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809. ; 104:3, s. 483-492
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Tidskriftsartikel (refereegranskat)abstract
- Ozone (O3) is a major phytotoxic air pollutant with the potential to cause severe yield losses in potato (Solanum tubersosum L.) and in other crops. The present study was aimed (i) to investigate the O3 sensitivity of two potato cultivars (Bintje and Kardal) in relation to their earliness in maturation, and (ii) to analyse possible O3 effects on potato tuber dry mass (DM) production in relation to leaf duration. The experiment was performed in the southwest of Sweden using open-top chamber (OTC) technique. The crops were exposed to three levels of O3: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air + 26 nmol mol−1 O3 (NF+). In addition, ambient air plots were used to monitor the impact of the OTC enclosure. Leaf number duration (LND) was calculated as the number of leaves integrated over the temperature sum accumulation during the season. In the present study, the O3 effects on potato were characterised by visible injury of the leaves and earlier leaf senescence. The haulm/plant DM ratio was significantly lower in NF+ compared to CF and NF. The conclusions were (i) that the early to intermediate maturing cultivar Bintje tended to suffer more from O3 injury than the late maturing cultivar Kardal, (ii) that this was due to a difference in the ability to compensate for haulm damage by the development of new leaves rather than to a difference in leaf O3 sensitivity, and (iii) that a rather low O3 exposure can induce a significant reduction in LND in potato. The O3 effects on tuber DM (−2% in NF+ and +31% increase in CF, both compared to NF) could not be statistically demonstrated, although there was a strong correlation between LND and tuber DM.
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| 4. |
- Skarby, L., et al.
(författare)
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Growth of Norway spruce (Picea abies) in relation to different ozone exposure indices: a synthesis
- 2004
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Ingår i: Atmospheric Environment. - 1352-2310. ; 38:15, s. 2225-2236
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Tidskriftsartikel (refereegranskat)abstract
- In the Goteborg Ozone-Spruce Project (GOSP), two independent open-top chamber experiments were conducted during four growing seasons, using one clone of Norway spruce (Picea abies). The experiments tested the impact of ozone, alone and in combination with low phosphorus supply and in combination with drought stress, respectively, on biomass accumulation. In this paper, the results from both experiments were combined for the first time in order to analyse the relationship between relative biomass accumulation and different exposure indices (accumulated exposure over a threshold (AOT) with different cut-off concentrations, and the sum of ozone concentrations above 60 nl l(-1), referred to as SUM06). In addition, a pooled analysis was made on several European studies of Norway spruce as a first effort to synthesize independent data and test the relative growth in relation to the AOT40 index. Significant negative relationships between the relative biomass of the GOSP-clone and the different indices were obtained. AOT20 and AOT30 resulted in the highest correlations. Based on the regression model, ozone is predicted to reduce the biomass of the GOSP-clone by 1% at the critical level for forest trees in Europe, a seasonal AOT40 of 10 mul l(-1) h. A significant negative relationship between relative growth and AOT40 was obtained also with the European data set. At the present ozone critical level, the model predicted a 6% reduction in growth for the most sensitive Norway spruce trees in this data set. (C) 2004 Elsevier Ltd. All rights reserved.
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| 5. |
- Uddling, Johan, 1972, et al.
(författare)
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Biomass reduction of juvenile birch is more strongly related to stomatal uptake of ozone than to indices based on external exposure
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:28, s. 4709-4719
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Tidskriftsartikel (refereegranskat)abstract
- In order to test the hypothesis that ozone-induced limitation of biomass production in juvenile silver birch (Betula pendula Roth) is driven by stomatal uptake of ozone (O-3) rather than external exposure, biomass reduction was related to the cumulative uptake of O-3 through stomata over an uptake cut-off threshold of x nmol O-3 m(-2) s(-1) (CUO > x), to the accumulated exposure to O-3 over a threshold of y nmol mol(-1) during daylight hours (daylight AOTy) or during 24 h (24 h AOTy), and to the sum of daytime concentrations exceeding 60 nmol mol(-1) (SUM06). The analysis included data from nine different experiments conducted in Sweden, Finland and Switzerland. Stomatal uptake of O-3 was estimated using a stomatal conductance (g,) model including g, response functions for photosynthetic photon flux density, water vapour pressure deficit of the air and air temperature. Experiment-specific maximum g(s) (g(max)) as well as g(s) in darkness (g(dark)) were assessed through local measurements. Biomass reduction Was more strongly related to CUO > x than to SUM06 and daylight or 24 h AOTy, but the difference between CUO > x and 24 h AOTy was small. The better performance of CUO > x was dependent on the use of site- and experiment-specific g(max) and g(dark) values, and there was a positive relationship between g(max) and biomass reduction per unit AOT40. Daylight AOTy and SUM06 could not account for the growth limiting impact of nocturnal O-3 uptake in the Swiss experiments. A sensitivity analysis revealed that the CUO > x estimates were largely insensitive to the estimate of the conductance for non-stomatal leaf surface deposition of O-3, as a result of turbulent conditions at the experimental plots. In summary, we conclude that CUO > x was more successful in accounting for the variation in biomass reduction in juvenile birch as compared to indices based on external exposure, if g(max) and g(dark) were locally parameterised. (C) 2004 Elsevier Ltd. All rights reserved.
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