| 1. |
- Holmstrup, Martin, et al.
(författare)
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Long-term and realistic global change manipulations had low impact on diversity of soil biota in temperate heathland
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- In a dry heathland ecosystem we manipulated temperature (warming), precipitation (drought) and atmospheric concentration of CO2 in a full-factorial experiment in order to investigate changes in below-ground biodiversity as a result of future climate change. We investigated the responses in community diversity of nematodes, enchytraeids, collembolans and oribatid mites at two and eight years of manipulations. We used a structural equation modelling (SEM) approach analyzing the three manipulations, soil moisture and temperature, and seven soil biological and chemical ariables. The analysis revealed a persistent and positive effect of elevated CO2 on litter C:N ratio. After two years of treatment, the fungi to bacteria ratio was increased by warming, and the diversities within oribatid mites, collembolans and nematode groups were all affected by elevated CO2 mediated through increased litter C:N ratio. After eight years of treatment, however, the CO2-increased litter C:N ratio did not influence the diversity in any of the four fauna groups. The number of significant correlations between treatments, food source quality, and soil biota diversities was reduced from six to three after two and eight years, respectively. These results suggest a remarkable resilience within the soil biota against global climate change treatments in the long term.
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| 2. |
- Igamberdiev, Abir U, et al.
(författare)
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Photorespiration Contributes to Stomatal Regulation and Carbon Isotope Fractionation: A Study with Barley, Potato and Arabidopsis Plants Deficient in Glycine Decarboxylase
- 2004
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Ingår i: Photosynthesis Research. ; 81, s. 139-152
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Tidskriftsartikel (refereegranskat)abstract
- The rates of respiration in light and darkness, C i/C a and carbon isotope fractionation were investigated in glycine decarboxylase-deficient plants of barley, potato and Arabidopsis thaliana grown in climate chambers with controlled light intensity, temperature, humidity, irradiation and different CO2 concentrations (360, 700 and 1400 µl l–1) and compared to the wild-type plants. All photorespiration-impaired plants exhibited higher C i/C a and corresponding lower apparent water-use efficiencies, which were more expressed under high irradiance and elevated temperature. The mutants were depleted in 13C as compared to the wild-type plants, with a difference of up to 6permil following growth in 360 µl l–1 CO2. We determined the carbon isotope content at different CO2 concentrations to calculate the contribution of both C i/C a and photorespiration for 13C/12C fractionation. The direct effect of photorespiration was in the range of 0.7–1.0permil, from which we calculated the value of fractionation at the site of glycine decarboxylation as being 10–13permil, which is in agreement with the previously reported carbon isotope discrimination exerted by the glycine decarboxylase. Respiratory rates, particularly in the light, were increased in the glycine decarboxylase mutants. The necessity of the maintenance of a high CO2 concentration near the site of carboxylation in chloroplasts in plants deficient in photorespiratory enzymes, requires an increased opening of the stomata with a corresponding decrease in water-use efficiency. It is concluded that photorespiration participates in the regulation of C i/C a and contributes to carbon isotope fractionation, both via effects on stomata and via discrimination of 13C in the glycine decarboxylase reaction.
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| 3. |
- Lin, Yan-Shih, et al.
(författare)
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Optimal stomatal behaviour around the world
- 2015
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 5, s. 459-464
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal conductance (gs) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycle changes, a globalscale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here,we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model1 and the leaf and wood economics spectrum2,3.We also demonstrate a global relationship with climate. These findings provide a robust theoretical framework for understanding and predicting the behaviour of gs across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.
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| 4. |
- Lin, Yan-Shih, et al.
(författare)
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Optimal stomatal behaviour around the world
- 2015
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Ingår i: Nature Climate Change. - 1758-6798 .- 1758-678X. ; 5:5, s. 459-464
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal conductance (g(s)) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of g(s) in predictions of global water and carbon cycle changes, a global-scale database and an associated globally applicable model of g(s) that allow predictions of stomatal behaviour are lacking. Here, we present a database of globally distributed g(s) obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model(1) and the leaf and wood economics spectrum(2,3). We also demonstrate a global relationship with climate. These findin g(s) provide a robust theoretical framework for understanding and predicting the behaviour of g(s) across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.
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| 5. |
- Linderson, Maj-Lena, et al.
(författare)
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Up-scaling of water use efficiency from leaf to canopy as based on leaf gas exchange relationships and the modeled in-canopy light distribution
- 2012
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 1873-2240 .- 0168-1923. ; 152, s. 201-211
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe aim of this study was to evaluate the extent to which water use efficiency (WUE) at leaf scale can be used to assess WUE at canopy scale, leaf WUE being assumed to be a constant function of vapor pressure deficit and to thus not be dependent upon other environmental factors or varying leaf properties. Leaf WUE and its variability and dependencies were assessed using leaf gas-exchange measurements obtained during two growing seasons, 1999 and 2000, at the Soroe beech forest study site on Zealand in Denmark. It was found that the VPD-normalized leaf VVUE, WUEnormleaf, although dependent on incoming PAR below 500 p,mol m(-2) s(-1) is independent, both of the canopy levels and of variations in the environmental parameters. The average WUEnormleaf for PAR above 500 mu mol m(-2) s(-1) was found to be 5.5 mu mol CO2 (mmol H2O)(-1) hPa and, for the full range, 2.3 mu mol CO2 (mmol H2O)(-1) hPa. These results showed that WUE can be up-scaled from leaf to canopy on the basis of WUEnormleaf and the PAR distribution within the canopy. The up-scaling conducted was based on this WUEnormleaf - PAR relationship, the light distribution being assessed using the MAESTRA model, parameterized in accordance with measurements obtained for the Soroe forest. The up-scaled WUE was then compared with WUE as estimated from turbulent flux data measured above the forest with the eddy-covariance technique. The modeled daily canopy WUE obtained for daytime fluxes (6:00 AM-6:00 PM) was found to be in agreement with corresponding canopy WUE estimates based on the turbulent fluxes observed and to be dependent on VDP and light intensity alone, its thus being independent of other environmental factors. Accordingly, canopy WUE can be estimated on the basis of the up-scaled WUE relationships, provided incident PAR and VPD within the canopy are known.
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