| 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. |
- Karlsson, Per Erik, 1957, et al.
(författare)
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Impact of ozone on the growth of birch (Betula pendula) saplings
- 2003
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Ingår i: Environmental Pollution. - 0269-7491. ; 124:3, s. 485-495
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Tidskriftsartikel (refereegranskat)abstract
- Saplings of one half-sib family of birch, Betula pendula, were exposed to three levels of ozone in open-top chambers (OTCs) during two growing seasons 1997-1998. The ozone treatments were non-filtered air (NF, accumulated daylight AOT40 over the two growing seasons of 3.0 mul l(-1) h), non-filtered air with extra ozone (NF +, accumulated daylight AOT40 of 27.3 mul l(-1) h) and nonfiltered air with additional extra ozone (NF++, accumulated daylight AOT40 of 120 mul l(-1) h), The birch saplings, including the roots, were harvested after the first and second growing seasons. After the first growing season, the NF++ treatment reduced the total wood biomass by 22%, relative to the NF treatment. There was no further reduction of the total wood biomass in the NF++ treatment after the second growing season. The root biomass was reduced by 30% after the first growing season. The shoot/root ratio, as well as the proportional biomass of leaves, were increased by ozone during both years. The ozone impact on the relative growth rate was estimated to -2% per 10 mul l(-1) h daylight AOT40 per growing season. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- 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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| 4. |
- Uddling, Johan, 1972, et al.
(författare)
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Measuring and modelling stomatal conductance and photosynthesis in mature birch in Sweden
- 2005
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923. ; 132:1-2, s. 115-131
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal conductance (g(s)), net photosynthesis (A(n)) and twig water potential (Psi(t)) were measured in mature silver birch (Betula pendula) during 3 years in southern Sweden. Measurements from 2 years were used to parameterise three different gs models and measurements from a 3rd year were used to validate these models. Two different multiplicative stomatal models were used. In one of these, the gs response function for the water vapour pressure deficit (D) was fixed, while in the other the g, sensitivity to D increased with the accumulated time after sunrise with D above a certain threshold value. Furthermore, one combined stomatal-photosynthesis model (L-model) was used. The L-model was run either by using observations of photosynthesis as input data, or by predicting g(s) and photosynthesis simultaneously from environmental data. The model used to predict photosynthesis was parameterised from measurements of the photosynthetic responses to the photosynthetically active radiation, CO2 and temperature. The stomatal response functions of the L-model were parameterised using observations of photosynthesis as input data in order to make them independent of the performance of the photosynthesis model. The difference in model performance between the two multiplicative models was relatively small. The multiplicative stomatal models and the L-model were similarly successful in predicting g(s) when the L-model was driven by observations of photosynthesis. However, the L-model was considerably less successful when photosynthesis was predicted. Photosynthesis was systematically under- and overestimated at high and low Psi(t), respectively, causing errors in the prediction of g(s). In most situations, measurements of photosynthesis are not available and g(s) must be predicted from environmental data. In such cases, we conclude that the two multiplicative models are more successful in predicting gs in mature silver birch than the combined stomatal-photosynthesis model. (c) 2005 Elsevier B.V. All rights reserved.
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