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- Aad, G., et al.
(författare)
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- 2011
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swepub:Mat__t (refereegranskat)
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| 6. |
- Silvola, J, et al.
(författare)
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Effects of elevated CO2 and N deposition on CH4 emissions from European mires
- 2003
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Ingår i: Global Biogeochemical Cycles. - 0886-6236. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- [1] Methane fluxes were measured at five sites representing oligotrophic peatlands along a European transect. Five study plots were subjected to elevated CO2 concentration (560 ppm), and five plots to NH4NO3 (3 or 5 g N yr(-1)). The CH4 emissions from the control plots correlated in most cases with the soil temperatures. The depth of the water table, the pH, and the DOC, N and SO4 concentrations were only weakly correlated with the CH4 emissions. The elevated CO2 treatment gave nonsignificantly higher CH4 emissions at three sites and lower at two sites. The N treatment resulted in higher methane emissions at three sites (nonsignificant). At one site, the CH4 fluxes of the N-treatment plots were significantly lower than those of the control plots. These results were not in agreement with our hypotheses, nor with the results obtained in some earlier studies. However, the results are consistent with the results of the vegetation analyses, which showed no significant treatment effects on species relationships or biomass production.
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| 7. |
- Miglietta, F, et al.
(författare)
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Spatial and Temporal Performance of the MiniFACE (Free Air CO2 Enrichment) System on Bog Ecosystems in Northern and Central Europe
- 2001
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Ingår i: Environmental Monitoring & Assessment. - 1573-2959. ; 66:2, s. 107-127
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Tidskriftsartikel (refereegranskat)abstract
- The Bog Ecosystem Research Initiative (BERI) projectwas initiated to investigate, at five climaticallydifferent sites across Europe, the effects of elevatedCO2 and N deposition on the net exchange ofCO2 and CH4 between bogs and the atmosphere,and to study the effects of elevated CO2 and Ndeposition on the plant biodiversity of bogcommunities. A major challenge to investigate theeffects of elevated CO2 on vegetation andecosystems is to apply elevated CO2concentrations to growing vegetation without changingthe physical conditions like climate and radiation.Most available CO2 enrichment methods disturb thenatural conditions to some degree, for instance closedchambers or open top chambers. Free Air CO2Enrichment (FACE) systems have proven to be suitableto expose plants to elevated CO2 concentrationswith minimal disturbance of their natural environment.The size and spatial scale of the vegetation studiedwithin the BERI project allowed the use of a modifiedversion of a small FACE system called MiniFACE. Thispaper describes the BERI MiniFACE design as well asits temporal and spatial performance at the five BERIfield locations. The temporal performance of theMiniFACE system largely met the quality criteriadefined by the FACE Protocol. One minute averageCO2 concentrations measured at the centre of thering stayed within 20% of the pre-set target for morethan 95% of the time. Increased wind speeds werefound to improve the MiniFACE system's temporalperformance. Spatial analyses showed no apparentCO2 gradients across a ring during a 4 day periodand the mean differences between each sampling pointand the centre of the ring did not exceed 10%.Observations made during a windy day, causing aCO2 concentration gradient, and observations madeduring a calm day indicated that short term gradientstend to average out over longer periods of time. On aday with unidirectional strong winds, CO2concentrations at the upwind side of the ring centrewere higher than those made at the centre and at thedownwind side of the ring centre, but the bell-shapeddistribution was found basically the same for thecentre and the four surrounding measurement points,implying that the short term (1 sec) variability ofCO2 concentrations across the MiniFACE ring isalmost the same at any point in the ring. Based on gasdispersion simulations and measured CO2concentration profiles, the possible interferencebetween CO2-enriched and control rings was foundto be negligible beyond a centre-to-centre ringdistance of 6 m.
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| 8. |
- Millett, J., et al.
(författare)
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Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia
- 2015
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 512, s. 631-636
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific.
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