| 1. |
- Oksanen, E., et al.
(författare)
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Northern environment predisposes birches to ozone damage
- 2007
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 9:2, s. 191-196
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Tidskriftsartikel (refereegranskat)abstract
- Ozone sensitivity of silver birch (Betula pendula Roth) has been thoroughly investigated since early 1990's in Finland. in our long-term open-field experiments the annual percentage reduction in basal diameter and stem volume increment were the best non-destructive growth indicators for ozone impact when plotted against AOTX. Remarkable differences in defence strategies, stomatal conductance, and defence compounds (phenolics), clearly indicate that external exposure indices are ineffective for accurate risk assessment for birch. For flux-based approaches, site-specific values for g(max) and g(dark) are necessary, and determinants for cletoxification capacity, ageing of leaves, and cumulative ozone impact would be needed for further model development. increasing CO2 seems to counteract negative ozone responses in birch, whereas exposure to springtime frost may seriously exacerbate ozone damage in northern conditions. Therefore, we need to proceed towards incorporating the most important climate change factors in any attempts for ozone risk assessment.
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| 2. |
- Kasurinen, A, et al.
(författare)
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Below-ground responses of silver birch trees exposed to elevated CO2 and O-3 levels during three growing seasons
- 2005
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 11:7, s. 1167-1179
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Tidskriftsartikel (refereegranskat)abstract
- Field-growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO2 and O-3 in open-top chambers for three consecutive growing seasons (1999-2001). At the beginning of the OTC experiment, all trees were 7 years old. We studied the single and interaction effects of CO2 and O-3 on silver birch below-ground carbon pools (i.e. effects on fine roots and mycorrhizas, soil microbial communities and sporocarp production) and also assessed whether there are any clonal differences in these below-ground CO2 and O-3 responses. The total mycorrhizal infection level of both clones was stimulated by elevated CO2 alone and elevated O-3 alone, but not when elevated CO2 was used in fumigation in combination with elevated O-3. In both clones, elevated CO2 affected negatively light brown/orange mycorrhizas, while its effect on other mycorrhizal morphotypes was negligible. Elevated O-3, instead, clearly decreased the proportions of black and liver-brown mycorrhizas and increased that of light brown/orange mycorrhizas. Elevated O-3 had a tendency to decrease standing fine root mass and sporocarp production as well, both of these O-3 effects mainly manifesting in clone 4 trees. CO2 and O-3 treatment effects on soil microbial community composition (PLFA, 2- and 3-OH-FA profiles) were negligible, but quantitative PLFA data showed that in 2001 the PLFA fungi : bacteria-ratio of clone 80 trees was marginally increased because of elevated CO2 treatments. This study shows that O-3 effects were most clearly visible at the mycorrhizal root level and that some clonal differences in CO2 and O-3 responses were observable in the below-ground carbon pools. In conclusion, the present data suggests that CO2 effects were minor, whereas increasing tropospheric O-3 levels can be an important stress factor in northern birch forests, as they might alter mycorrhizal morphotype assemblages, mycorrhizal infection rates and sporocarp production.
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| 3. |
- Kostiainen, K., et al.
(författare)
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Stem wood properties of mature Norway spruce after 3 years of continuous exposure to elevated [CO2] and temperature
- 2009
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 15:2, s. 368-379
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study was to investigate the interactive effects of elevated atmospheric carbon dioxide concentration, [CO2], and temperature on the wood properties of mature field-grown Norway spruce (Picea abies (L.) Karst.) trees. Material for the study was obtained from an experiment in Flakaliden, northern Sweden, where trees were grown for 3 years in whole-tree chambers at ambient (365 ÎŒmol mol-1) or elevated [CO2] (700 ÎŒmol mol-1) and ambient or elevated air temperature (ambient +5.6°C in winter and ambient +2.8°C in summer). Elevated temperature affected both wood chemical composition and structure, but had no effect on stem radial growth. Elevated temperature decreased the concentrations of acetone-soluble extractives and soluble sugars, while mean and earlywood (EW) cell wall thickness and wood density were increased. Elevated [CO2] had no effect on stem wood chemistry or radial growth. In wood structure, elevated [CO2] decreased EW cell wall thickness and increased tracheid radial diameter in latewood (LW). Some significant interactions between elevated [CO2] and temperature were found in the anatomical and physical properties of stem wood (e.g. microfibril angle, and LW cell wall thickness and density). Our results show that the wood material properties of mature Norway spruce were altered under exposure to elevated [CO2] and temperature, although stem radial growth was not affected by the treatments. © 2008 The Authors Journal compilation © 2008 Blackwell Publishing.
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| 4. |
- Kostiainen, Katri, et al.
(författare)
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Wood properties of Populus and Betula in long-term exposure to elevated CO2 and O3
- 2014
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 37:6, s. 1452-1463
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Tidskriftsartikel (refereegranskat)abstract
- We studied the interactive effects of elevated concentrations of CO2 and O3 on radial growth and wood properties of four trembling aspen (Populus tremuloidesMichx.) clones and paper birch (Betula papyriferaMarsh.) saplings. The material for the study was collected from the Aspen FACE (free-air CO2 enrichment) experiment in Rhinelander (WI, USA). Trees had been exposed to four treatments [control, elevated CO2 (560ppm), elevated O3 (1.5 times ambient) and combined CO2+O3] during growing seasons 1998-2008. Most treatment responses were observed in the early phase of experiment. Our results show that the CO2- and O3-exposed aspen trees displayed a differential balance between efficiency and safety of water transport. Under elevated CO2, radial growth was enhanced and the trees had fewer but hydraulically more efficient larger diameter vessels. In contrast, elevated O3 decreased radial growth and the diameters of vessels and fibres. Clone-specific decrease in wood density and cell wall thickness was observed under elevated CO2. In birch, the treatments had no major impacts on wood anatomy or wood density. Our study indicates that short-term impact studies conducted with young seedlings may not give a realistic view of long-term ecosystem responses.
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