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| 2. |
- Karlsson, Per Erik, 1957, et al.
(författare)
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Increasing risk for negative ozone impacts on vegetation in northern Sweden
- 2007
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Ingår i: Environmental Pollution. ; 150, s. 96-106
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Tidskriftsartikel (refereegranskat)abstract
- Trends were found for increasing surface ozone concentrations during AprileSeptember in northern Sweden over the period 1990e2006 as well as for an earlier onset of vegetation growing season. The highest ozone concentrations in northern Sweden occurred in April and the ozone concentrations in April showed a strong increasing trend. A model simulation of ozone flux for Norway spruce indicated that the provisional ozone flux based critical level for forests in Europe is exceeded in northern Sweden. Future climate change would have counteracting effects on the stomatal conductance and needle ozone uptake, mediated on the one hand by direct effect of increasing air temperatures and on the other through increasing water vapour pressure difference between the needles and air. Thus, there is a substantial and increasing risk for negative impacts of ozone on vegetation in northern Sweden, related mainly to increasing ozone concentrations and an earlier onset of the growing season.
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| 4. |
- Klingberg, Jenny, 1978, et al.
(författare)
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NO, NO2 and O3 concentrations in the polluted urban landscape in comparison with a rooftop urban monitoring site and a rural site – influence of meteorology
- 2007
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Ingår i: Proceedings of the International Conference on Environmental Management, Engineering, Planning and Economics (CEMEPE), 24-28 June 2007, Skiathos, Greece. - 9789608981812 ; 4, s. 2423-2428
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Mills, G., et al.
(författare)
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A synthesis of AOT40-based response functions and critical levels of ozone for agricultural and horticultural crops
- 2007
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 41:12, s. 2630-2643
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Tidskriftsartikel (refereegranskat)abstract
- Crop-response data from over 700 published papers and conference proceedings have been analysed with the aim of establishing ozone dose-response functions for a wide range of European agricultural and horticultural crops. Data that met rigorous selection criteria (e.g. field-based, ozone concentrations within European range, full season exposure period) were used to derive AOT40-yield response functions for 19 crops by first converting the published ozone concentration data into AOT40 (AOT40 is the hourly mean ozone concentration accumulated over a threshold ozone concentration of 40ppb during daylight hours, units ppmh). For any individual crop, there were no significant differences in the linear response functions derived for experiments conducted in the USA or Europe, or for individual cultivars. Three statistically independent groups were identified: ozone sensitive crops (wheat, water melon, pulses, cotton, turnip, tomato, onion, soybean and lettuce); moderately sensitive crops (sugar beet, potato, oilseed rape, tobacco, rice, maize, grape and broccoli) and ozone resistant (barley and fruit represented by plum and strawberry). Critical levels of a 3 month AOT40 of 3 ppm It and a 3.5 month AOT40 of 6ppm h were derived from the functions for wheat and tomato, respectively. (c) 2006 Elsevier Ltd. All rights reserved.
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| 6. |
- Piikki, Kristin, 1975, et al.
(författare)
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Impact of elevated O3 and CO2 exposure on potato (Solanum tuberosum L. cv. Bintje) tuber macronutrients (N, P, K, Mg, Ca)
- 2007
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809. ; 118:1-4, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- It was investigated whether exposure of elevated ozone (O3) and carbon dioxide (CO2) concentrations affected the macronutrient (N, P, K, Mg, Ca) concentrations in potato (Solanum tuberosum L.) tubers in three open-top chamber experiments from Sweden and Finland. The tuber concentrations of N, P, K and Mg correlated positively with O3 exposure (although not significantly in the case of N and P) but the O3 exposure had no effect on the tuber concentration of Ca. A likely mechanism behind the observed O3 effects was suggested to be that the more progressed senescence of O3 exposed plants was associated with a larger extent of reallocation of mobile nutrients from the haulm to the tubers. In addition, the uptake of macronutrients may have been less negatively affected by O3 exposure than the assimilation of carbon. O3 tended to reduce the total tuber contents of all investigated nutrients, which imply a reduced fertilizer need per unit field area. This was not associated with a decreased fertilizer need per tonnage of yield, as the tuber nutrient concentrations were increased by O3 exposure. The increased CO2 concentration did not significantly affect any of the investigated macronutrients in the present dataset but did generally prevent the O3 induced increases in nutrient concentrations to be expressed (only significant in the case of N and Mg). The O3 induced increase in tuber K concentration, may mediate earlier observed O3 effects on potato tuber concentrations of citric and malic acids. To conclude, anticipated future (and even presently occurring) O3 exposure has a negative impact on the total tuber contents of K and Ca and probably also on the total tuber contents of N, P and Mg. O3 exposure causes increased tuber concentrations of N, P, K and Mg at an early harvest. The O3 induced increase in tuber concentration tended to diminish by a CO2 elevation.
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| 7. |
- Pleijel, Håkan, 1958, et al.
(författare)
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Ozone risk assessment for agricultural crops in Europe: Further development of stomatal flux and flux-response relationships for European wheat and potato
- 2007
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 41:14, s. 3022-3040
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Tidskriftsartikel (refereegranskat)abstract
- Applications of a parameterised Jarvis-type multiplicative stomatal conductance model with data collated from open-top chamber experiments on field grown wheat and potato were used to derive relationships between relative yield and stomatal ozone uptake. The relationships were based on thirteen experiments from four European countries for wheat and seven experiments from four European countries for potato. The parameterisation of the conductance model was based both on an extensive literature review and primary data. Application of the stomatal conductance models to the open-top chamber experiments resulted in improved linear regressions between relative yield and ozone uptake compared to earlier stomatal conductance models, both for wheat (r(2) = 0.83) and potato (r(2) = 0.76). The improvement was largest for potato. The relationships with the highest correlation were obtained using a stomatal ozone flux threshold. For both wheat and potato the best performing exposure index was AF(st)6 (accumulated stomatal flux of ozone above a flux rate threshold of 6 nmol ozone m(-2) projected sunlit leaf area, based on hourly values of ozone flux). The results demonstrate that flux-based models are now sufficiently well calibrated to be used with confidence to predict the effects of ozone on yield loss of major arable crops across Europe. Further studies, using innovations in stomatal conductance modelling and plant exposure experimentation, are needed if these models are to be further improved. (c) 2006 Elsevier Ltd. All rights reserved.
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| 9. |
- Uddling, Johan, 1972, et al.
(författare)
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Evaluating the relationship between leaf chlorophyll concentration and SPAD-502 chlorophyll meter readings
- 2007
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Ingår i: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 91:3, s. 37-46
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between chlorophyll concentration ([chl]) and SPAD values were determined for birch, wheat, and potato. For all three species, the relationships were non-linear with an increasing slope with increasing SPAD. The relationships for birch and wheat were strong (r(2) similar to 0.9), while the potato relationship was comparatively weak (r(2) similar to 0.5). Birch and wheat had very similar relationships when the chlorophyll concentration was expressed per unit leaf area, but diverged when it was expressed per unit fresh weight. Furthermore, wheat showed similar SPAD-[chl] relationships for two different cultivars and during two different growing seasons. The curvilinear shape of the SPAD-[chl] relationships agreed well with the simulated effects of non-uniform chlorophyll distribution across the leaf surface and multiple scattering, causing deviations from linearity in the high and low SPAD range, respectively. The effect of non-uniformly distributed chlorophyll is likely to be more important in explaining the non-linearity in the empirical relationships, since the effect of scattering was predicted to be comparatively weak. The simulations were based on the algorithm for the calculation of SPAD-502 output values. We suggest that SPAD calibration curves should generally be parameterised as non-linear equations, and we hope that the relationships between [chl] and SPAD and the simulations of the present study can facilitate the interpretation of chlorophyll meter calibrations in relation to optical properties of leaves in future studies.
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