Publikationen
Es wurden 28 Publikationen gefunden
Liebermann, R.; Kraft, P.; Houska, T.; Müller, C.; Kraus, D.; Haas, E.; Klatt, S. & Breuer, L. (2015-04-17). Uncertainty analysis of a coupled ecosystem response model simulating greenhouse gas fluxes from a temperate grassland. Presented at European Geosciences Union General Assembly 2015, Vienna, Austria.
Keidel, L.; Lenhart, K.; Moser, G. & Müller, C. (2018): Depth-dependent response of soil aggregates and soil organic carbon content to long-term elevated CO2 in a temperate grassland soil. Soil Biology and Biochemistry 123, 145-154
DOI: http://dx.doi.org/https://doi.org/10.1016/j.soilbio.2018.05.005.
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DOI: https://doi.org/10.1016/j.soilbio.2018.05.005
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Abstract:
Abstract:
Facing rising atmospheric CO2 concentrations, subsoils may play an important role in the global carbon (C) cycle due to the presence of unsaturated mineral surfaces. Further, macroaggregation is considered a crucial process influencing C sequestration. However, analyses on subsoil aggregation and C retention processes under long-term elevated CO2 (eCO2) are lacking. In this study we investigated the long-term effect of +20% above ambient CO2 concentration (corresponds to conditions reached 2035–2045) in a temperate grassland ecosystem at the Giessen Free Air CO2 Enrichment (Gi-FACE), Germany. A depth-dependent response of macroaggregation to eCO2 was observed: While in subsoil (15–45?cm depth) macroaggregation increased under eCO2, no CO2 induced change in macroaggregation was detected in topsoil (0–15?cm). Increased macroaggregation in subsoil coincided with higher SOC content of large macroaggregates (LM). Mean residence time (MRT) of SOC in aggregate-size classes were not different among each other under eCO2. However, macroaggregates and bulk soil differed in their MRT between soil depths. Despite increased macroaggregation and an estimated high SOC sequestration potential in subsoil we could not observe an increase in SOC content of bulk soil.
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Keywords: |
eCO2 |
climate change |
grassland |
Giessen FACE |
C sequestration |
SOC dynamics |
soil structure |
subsoil |
carbon cycle |
Seibert, R. (2015-10-01). Impacts of long-term atmospheric CO2 enrichment on the soil seed bank in a temperate grassland. Presented at 8th GGL Conference on Life Sciences, Gießen, Germany.
Grünhage, L.; Kammann, C. & Moser, G. (2016-01-07). GiFACE Sampling Design. Presented at Internal Presentation, Giessen.
Moser, G.; Gorenflo, A.; Brenzinger, K.; Keidel, L.; Braker, G.; Marhan, S.; Clough, T.J. & Müller, C. (2018): Explaining the doubling of N2O emissions under elevated CO2 in the Giessen FACE via in-field 15N tracing. Global Change Biology early view, 1-14
DOI: http://dx.doi.org/10.1111/gcb.14136 | Revised: 12 January 2018.
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DOI: 10.1111/gcb.14136 | Revised: 12 January 2018
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Abstract:
Abstract:
Rising atmospheric CO2 concentrations are expected to increase nitrous oxide (N2O) emissions from soils via changes in microbial nitrogen (N) transformations triggering a positive feedback reaction that could accelerate climate change. Several studies have shown N2O emission increases under elevated atmospheric CO2 (eCO2), but the underlying processes are not yet fully understood. Here we present results showing changes in soil N transformation dynamics from the Giessen Free Air CO2 Enrichment (GiFACE): a permanent grassland that has been exposed to eCO2, +20% relative to ambient concentrations (aCO2), for 15 years. We applied in the field an ammonium-nitrate fertilizer solution, in which either ammonium (NH4+) or nitrate (NO3-) was labelled with 15N. The simultaneous gross N transformation rates were analysed with a 15N tracing model and a solver method. The results confirmed that after 15 years of eCO2 the N2O emissions under eCO2 were still more than 2-fold higher than under aCO2. The tracing model results indicated that plant uptake of NH4+ did not differ between treatments, but uptake of NO3- was significantly reduced under eCO2. However, the ratio of gross production and consumption of NH4+ remained unchanged under eCO2, but decreased slightly for NO3-, which increased NO3- availability under eCO2. The N2O isotopic signature indicated that under eCO2 the sources of the additional emissions, 8407 µg N2O-N m-2 during the first 58 days after labelling, were associated with NO3- reduction (+2.0%), NH4+ oxidation (+11.1%) and organic N oxidation (+86.9%). We presume that increased root exudation under eCO2 provided an additional source of bioavailable supply of energy that triggered the stimulation of microbial soil organic matter (SOM) mineralization, as a priming effect, and an increased activity of bacterial nitrite reductase, which caused the shift in N2O:N2 emission ratio, via incomplete denitrification, explaining the positive feedback reaction of doubled N2O emissions.
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Keywords: |
climate change |
elevated CO2 |
grassland |
Giessen-FACE |
Giessen FACE |
Gi-FACE |
Gross N transformation |
free air carbon dioxide enrichment |
long-term response |
N transformation |
N2O emission |
positive climate change feedback |
Kellner, J. (2014-09-18). Development of a coupled hydrological-plant growth model for grasslands under elevated CO2. Presented at 7th GGL Conference on Life Sciences, Gießen, Germany.
Aydogan, E.; Busse, H.; Moser, G.; Müller, C.; Kämpfer, P. & Glaeser, S.P. (2016): Aureimonas galii sp. nov. and Aureimonas pseudogalii sp. nov. isolated from the phyllosphere of Galium album. International Journal of Systematics and Evolutionary Microbiology 66, 3345-3354
DOI: http://dx.doi.org/10.1099/ijsem.0.001200.
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DOI: 10.1099/ijsem.0.001200
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Abstract:
Abstract:
Four yellow-pigmented, Gram-stain-negative, rod-shaped bacteria, strains PP-WC-4G-234T, PP-CE-2G-454T, PP-WC-1G-202 and PP-CC-3G-650, were isolated from the phyllosphere of Galium album. The strains shared 99.7–100?% 16S rRNA gene sequence similarity but could be differentiated by genomic fingerprinting using rep- and random amplification of polymorphic DNA PCRs. Phylogenetic analysis based on the 16S rRNA gene placed the strains within the family Aurantimonadaceae with highest 16S rRNA gene sequence similarity of 97.2–97.3?% to the type strain of Aureimonas phyllosphaerae. Sequence similarities to all other Aurantimonadaceae were below 97?%. The main cellular fatty acids of the strains were C18?:?1 ?7c as the predominant fatty acid followed by C16?:?0 and summed feature 3 (C16?:?1 ?7c/C16?:?1 ?8c). The polyamine patterns of strains PP-WC-4G-234T and PP-CE-2G-454T contained sym-homospermidine as a major compound, and the major respiratory quinone was ubiquinone Q-10. Predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, phosphatidylcholine, sulfoquinovosyldiacylglycerol, three unidentified phospholipids and one unidentified lipid only detectable after total lipid staining. The DNA G+C content was 66.4, 68.9, 67.4 and 70.5 mol% for strains PP-WC-4G-234T, PP-CE-2G-454T, PP-WC-1G-202 and PP-CC-3G-650, respectively. Based on phylogenetic, chemotaxonomic and phenotypic analyses we propose two novel species of the genus Aureimonas, Aureimonas galii sp. nov. with PP-WC-4G-234T (=LMG 28655T=CIP 110892T) as the type strain and Aureimonas pseudogalii sp. nov. with PP-CE-2G-454T (=LMG 29411T=CCM 8665T) as the type strain and two further strains representing the same species, PP-WC-1G-202 and PP-CC-3G-650.
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Keywords: |
grassland |
Epiphytic Microbial Community |
grassland ecology |
Jansen-Willems, A.B.; Lanigan, G.J.; Grünhage, L. & Müller, C. (2016): Carbon cycling in temperate grassland under elevated temperature. Ecology and Evolution In press, In press
DOI: http://dx.doi.org/In press.
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DOI: In press
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Abstract:
Abstract:
An increase in mean soil surface temperature has been observed over the last century and it is predicted to further increase in the future. The effect of increased temperature on ecosystem carbon fluxes in a permanent temperate grassland, was studied in a long term (6 years) field experiment, using multiple temperature increments induced by IR-lamps. Ecosystem respiration (R-eco) and net ecosystem exchange (NEE) were measured, and modelled by a modified Lloyd and Taylor model including a soil moisture component for R-eco (average R2 of 0.78) and inclusion of a photosynthetic component based on temperature and radiation for NEE (R2=0.65). Modelled NEE values ranged between 2.3 and 5.3 kg CO2 m-2 year-1, depending on treatment. An increase of 2 or 3°C led to increased carbon losses, lowering the carbon storage potential by around 4 tonnes of C ha-1 year-1. The majority of significant NEE differences were found during night-time compared to daytime. This suggests that during daytime the increased respiration could be offset by an increase in photosynthetic uptake. This was also supported by differences in ?13C and ?18O, indicating prolonged increased photosynthetic activity associated with the higher temperature treatments. However, this increase in photosynthesis was insufficient to counteract the 24hr increase in respiration, explaining the higher CO2 emissions due to elevated temperature.
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Keywords: |
CO2 |
grassland |
Heating |
elevated temperature |
respiration |
net ecosystem exchange |
isotopes |
Kellner, J.; Multsch, S.; Kraft, P.; Houska, T.; Müller, C. & Breuer, L. (2016-02-15). Uncertainty analysis of a coupled hydrological-plant growth model for grassland under elevated CO2. Presented at Agriculture and Climate Change - Adapting Crops to Increased Uncertainty (AGRI 2015), Amsterdam.
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Abstract:
Abstract:
The continuous increase in atmospheric carbon dioxide (CO2) contributes to changes in plant evapotranspiration and terrestrial water Budgets in two ways. Firstly, elevated CO2 can result in a water saving effect, since increasing CO2 reduces stomatal opening and therefore decreases transpiration. Secondly, CO2 fertilization increases biomass accumulation and leaf area at plant canopy Level, likely increasing plant transpiration. Vegetation and hydrological models can be used to investigate the CO2 Response and the bidirectional effects outlined above, including their relative contribution to the changes in the water cycle. However, the intrinsic plant-soil interaction and the uncertainty related to model parameterization have rarely been considered.
Hence, we coupled a detailed plant growth and soil hydrological model by using the generic model frameworks Plant growth Modelling Framework (PMF) and Catchment Modelling Framework (CMF). Up to date response mechanisms have been implemented in PMF to simulate the various ways of how plant physiology is influenced by elevated CO2. Both models interact by using the Python computer language. Applying the coupled PMF-CMF model we investigate the effects of elevated CO2 in a number of plant physiological and environmental variables such as biomass, leaf area index and soil moisture using field data of a long-term Free Air Carbon dioxide Enrichment (FACE) Experiment in Giessen, Germany. In this Experiment, various grassland varieties (herbs, legumes, grasses) grow under elevated (+20%) and ambient CO2 since 1997.
A Monte Carlo based uncertainty analysis (GLUE) is conducted to investigate the coupled PMF-CMF parameter space. The focus will be on the identification of parameters for plant and soil, which are the drivers for the CO2 Response of the terrestrial water balance. We will present first results of the simulation of biomass accumulation and transpiration under ambient and elevated CO2 concentrations.
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Keywords: |
elevated CO2 |
grassland |
plant growth |
uncertainty analysis |
coupled model |
water balance |
Liebermann, R.; Kraft, P. & Breuer, L. (2016-09-13). Simulation von Biomasse und Treibhausgasemissionen eines FACE-Grünlandexperiments unter Grundwassereinfluss. Presented at Begutachtung LOEWE-Schwerpunkt FACE2FACE, Giessen, Germany.
Kellner, J. (2015-10-01). Modelling temperate grasslands under elevated CO2 with a coupled hydrological-plant growth model. Presented at 8th GGL Conference on Life Sciences, Gießen, Germany.
Seibert, R. (2016-09-20). Impacts of long-term atmospheric CO2 enrichment on the species dynamics and aboveground biomass production of a periodically wet grassland. Presented at 9th GGL Conference on Life Sciences, Gießen, Germany.
Obermeier, W.; Lehnert, L.W.; Kammann, C.; Müller, C.; Grünhage, L.; Luterbacher, J.; Erbs, M.; Moser, G.; Seibert, R.; Yuan, N. & Bendix, J. (2016): Reduced CO2 fertilization effect in temperate C3 grasslands under more extreme weather conditions. Nature Climate Change 7(2), 137-141
DOI: http://dx.doi.org/10.1038/nclimate3191.
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DOI: 10.1038/nclimate3191
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Abstract:
Abstract:
The increase in atmospheric greenhouse gas concentrations from anthropogenic activities is the major driver of recent global climate change1. The stimulation of plant photosynthesis due to rising atmospheric carbon dioxide concentrations ([CO2]) is widely assumed to increase the net primary productivity (NPP) of C3 plants—the CO2 fertilization effect (CFE). However, the magnitude and persistence of the CFE under future climates, including more frequent weather extremes, are controversial. Here we use data from 16 years of temperate grassland grown under ‘free-air carbon dioxide enrichment’ conditions to show that the CFE on above-ground biomass is strongest under local average environmental conditions. The observed CFE was reduced or disappeared under wetter, drier and/or hotter conditions when the forcing variable exceeded its intermediate regime. This is in contrast to predictions of an increased CO2 fertilization effect under drier and warmer conditions. Such extreme weather conditions are projected to occur more intensely and frequently under future climate scenarios. Consequently, current biogeochemical models might overestimate the future NPP sink capacity of temperate C3 grasslands and hence underestimate future atmospheric [CO2] increase.
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Keywords: |
climate change |
grassland |
GiFACE |
CO2 fertilization |
Elevated carbon dioxide |
grassland ecology |
ecophysiology |
Liebermann, R.; Kraft, P.; Houska, T.; Müller, C.; Haas, E.; Kraus, D.; Klatt, S.; Kiese, R. & Breuer, L. (2014-07-15). Simulating fluxes of N and C under elevated atmospheric CO2 in a coupled ecosystem response model. Presented at BIOGEOMON 2014, Bayreuth, Germany.
Moser, G.; Gorenflo, A.; Brenzinger, K.; Keidel, L.; Braker, G.; Marhan, S.; Clough, T.J. & Müller, C. (2018): Explaining the doubling of N2O emissions under elevated CO2 in the Giessen FACE via in-field 15N tracing. Global Change Biology 24, 3897-3910
DOI: http://dx.doi.org/10.1111/gcb.14136.
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DOI: 10.1111/gcb.14136
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Abstract:
Abstract:
Rising atmospheric CO2 concentrations are expected to increase nitrous oxide (N2O)
emissions from soils via changes in microbial nitrogen (N) transformations. Several
studies have shown that N2O emission increases under elevated atmospheric CO2
(eCO2), but the underlying processes are not yet fully understood. Here, we present
results showing changes in soil N transformation dynamics from the Giessen Free Air
CO2 Enrichment (GiFACE): a permanent grassland that has been exposed to eCO2,
+20% relative to ambient concentrations (aCO2), for 15 years. We applied in the field
an ammonium-nitrate fertilizer solution, in which either ammonium (NHþ
4 ) or nitrate
(NO
3 ) was labelled with 15N. The simultaneous gross N transformation rates were
analysed with a 15N tracing model and a solver method. The results confirmed that
after 15 years of eCO2 the N2O emissions under eCO2 were still more than twofold
higher than under aCO2. The tracing model results indicated that plant uptake of NHþ
4
did not differ between treatments, but uptake of NO
3 was significantly reduced under
eCO2. However, the NHþ
4 and NO
3 availability increased slightly under eCO2. The
N2O isotopic signature indicated that under eCO2 the sources of the additional emissions,
8,407 lg N2O–N/m2 during the first 58 days after labelling, were associated
with NO
3 reduction (+2.0%), NHþ
4 oxidation (+11.1%) and organic N oxidation
(+86.9%). We presume that increased plant growth and root exudation under eCO2
provided an additional source of bioavailable supply of energy that triggered as a priming
effect the stimulation of microbial soil organic matter (SOM) mineralization and
fostered the activity of the bacterial nitrite reductase. The resulting increase in incomplete
denitrification and therefore an increased N2O:N2 emission ratio, explains the
doubling of N2O emissions. If this occurs over a wide area of grasslands in the future,
this positive feedback reaction may significantly accelerate climate change.
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Keywords: |
climate change |
elevated CO2 |
grassland |
free air carbon dioxide enrichment |
long-term response |
N transformation |
N2O emission |
positive climate change feedback |
Kellner, J. (2016-09-21). Simulating the effect of elevated CO2 on plant growth of a temperate grassland using a coupled hydrological-plant growth model. Presented at 9th GGL Conference on Life Sciences, Gießen, Germany.
Seibert, R. (2014-09-18). Population dynamics, phenology and yield of grassland. Presented at 7th GGL Conference on Life Sciences, Gießen.
Aydogan, E.; Busse, H.; Moser, G.; Müller, C.; Kämpfer, P. & Glaeser, S.P. (2016): Proposal of Mucilaginibacter phyllosphaerae sp. nov. isolated from the phyllosphere of Galium album. International Journal of Systematics and Evolutionary Microbiology 66, 4138-4147
DOI: http://dx.doi.org/10.1099/ijsem.0.001326.
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DOI: 10.1099/ijsem.0.001326
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Abstract:
Abstract:
A pink-pigmented, Gram-stain-negative, rod-shaped, non-spore-forming bacterial strain, PP-F2F-G21T, was isolated from the phyllosphere of Galium album. Phylogenetic analysis of the nearly full-length 16S rRNA gene sequence of strain PP-F2F-G21T showed the closest relationship to type strains of the species Mucilaginibacter lutimaris (97.7?%), Mucilaginibacter soli (97.3?%) and Mucilaginibacter rigui (97.1?%). Sequence similarities to all other type strains were below 97?%. The predominant cellular fatty acids of strain PP-F2F-G21T are C16?:?1 ?7c/iso-C15?:?0 2-OH (measured as summed feature 3 fatty acids) and iso-C15?:?0 followed by iso-C17?:?0 3-OH, C16?:?1 ?5c and C16?:?0. The major compound in the polyamine pattern was sym-homospermidine and the diamino acid of the peptidoglycan was meso-diaminopimelic acid. The quinone system was exclusively composed of menaquinone MK-7. The polar lipid profile contained the major lipid phosphatidylethanolamine and in addition 18 unidentified lipids. Based on phylogenetic, chemotaxonomic and phenotypic analyses, we propose a novel species of the genus Mucilaginibacter named Mucilaginibacter phyllosphaerae sp. nov. The type strain is PP-F2F-G21T (=CCM 8625T=CIP 110921T=LMG 29118T).
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Keywords: |
grassland |
Epiphytic Microbial Community |
grassland ecology |
Seibert, R. (2017-07-04). Populationsdynamik, Phänologie und Ertrag im Grünland. Presented at FACE2FACE-Vollversammlung, Gießen.
Obermeier, W. (2017-07-04). Future summer aboveground biomass in a temperate C3 grassland. Presented at General Assembly - FACE2FACE, Giessen.