Publikationen
Es wurden 28 Publikationen gefunden
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.
-
link
-
view metadata
-
DOI: 10.1111/gcb.14136
-
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.
-
Keywords: |
climate change |
elevated CO2 |
grassland |
free air carbon dioxide enrichment |
long-term response |
N transformation |
N2O emission |
positive climate change feedback |
Keidel, L.; Kammann, C.; Grünhage, L.; Moser, G. & Müller, C. (2015): Long term CO2 enrichment in a temperate grassland increases soil respiration during late autumn and winter. Biogeoscience 12, 1257-1269
DOI: http://dx.doi.org/10.5194/bg-12-1257-2015.
-
log in to download
-
log in to download
-
link
-
view metadata
-
DOI: 10.5194/bg-12-1257-2015
-
Abstract:
Abstract:
Soil respiration of terrestrial ecosystems, a major component in the global carbon cycle is affected by elevated atmospheric CO2 concentrations. However, seasonal differences of feedback effects of elevated CO2 have rarely been studied. At the Gießen Free-Air CO2 Enrichment (GiFACE) site, the effects of +20% above ambient CO2 concentration have been investigated since 1998 in a temperate grassland ecosystem. We defined five distinct annual seasons, with respect to management practices and phenological cycles. For a period of 3 years (2008–2010), weekly measurements of soil respiration were carried out with a survey chamber on vegetation-free subplots. The results revealed a pronounced and repeated increase of soil respiration under elevated CO2 during late autumn and winter dormancy. Increased CO2 losses during the autumn season (September–October) were 15.7% higher and during the winter season (November–March) were 17.4% higher compared to respiration from ambient CO2 plots.
However, during spring time and summer, which are characterized by strong above- and below-ground plant growth, no significant change in soil respiration was observed at the GiFACE site under elevated CO2. This suggests (1) that soil respiration measurements, carried out only during the growing season under elevated CO2 may underestimate the true soil-respiratory CO2 loss (i.e. overestimate the C sequestered), and (2) that additional C assimilated by plants during the growing season and transferred below-ground will quickly be lost via enhanced heterotrophic respiration outside the main growing season.
-
Keywords: |
temperature |
soil |
aCO2 |
climate change |
elevated CO2 |
FACE |
soil respiration |
grassland |
Seibert, R. (2017-07-04). Populationsdynamik, Phänologie und Ertrag im Grünland. Presented at FACE2FACE-Vollversammlung, Gießen.
Seibert, R. (2017-03-28). Impacts of 19 years long atmospheric CO2 enrichment on aboveground biomass production and population dynamics of a periodically wet grassland. Presented at 2nd Agriculture and Climate Change Conference - Climate ready resource use-efficient crops to sustai, Sitges, Spain.
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.
-
log in to download
-
link
-
view metadata
-
DOI: In press
-
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.
-
Keywords: |
CO2 |
grassland |
Heating |
elevated temperature |
respiration |
net ecosystem exchange |
isotopes |
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.
Seibert, R. (2014-09-18). Population dynamics, phenology and yield of grassland. Presented at 7th GGL Conference on Life Sciences, Gießen.
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.
Liebermann, R.; Kraft, P.; Houska, T.; Müller, C.; Kraus, D.; Klatt, S.; Haas, E. & Breuer, L. (2016-09-21). How groundwater controls the cycles of C and N - A modelling study from a temperate grassland experiment. Presented at 9thAnnual GGL Conference 2016, Giessen, Germany.
Liebermann, R. (2017-07-04). Interaktion der simulierten Wasser- und N-Kreisläufe des Linden FACE Grünlands. Presented at FACE2FACE Vollversammlung 2017, JLU Giessen.
Aydogan, E.; Moser, G.; Müller, C.; Kämpfer, P. & Glaeser, S.P. (2018): Long-term warming shifts the composition of bacterial communities in the phyllosphere of Galium album in a permanent grassland field-experiment. . Frontiers in Microbiology 9, 144
DOI: http://dx.doi.org/10.3389/fmicb.2018.00144.
-
log in to download
-
link
-
view metadata
-
DOI: 10.3389/fmicb.2018.00144
-
Abstract:
Abstract:
Global warming is currently a much discussed topic with as yet largely unexplored consequences for agro-ecosystems. Little is known about the warming effect on the bacterial microbiota inhabiting the plant surface (phyllosphere), which can have a strong impact on plant growth and health, as well as on plant diseases and colonization by human pathogens. The aim of this study was to investigate the effect of moderate surface warming on the diversity and composition of the bacterial leaf microbiota of the herbaceous plant Galium album. Leaves were collected from four control and four surface warmed (+2°C) plots located at the field site of the Environmental Monitoring and Climate Impact Research Station Linden in Germany over a 6-year period. Warming had no effect on the concentration of total number of cells attached to the leaf surface as counted by Sybr Green I staining after detachment, but changes in the diversity and phylogenetic composition of the bacterial leaf microbiota analyzed by bacterial 16S rRNA gene Illumina amplicon sequencing were observed. The bacterial phyllosphere microbiota were dominated by Proteobacteria, Bacteroidetes, and Actinobacteria. Warming caused a significant higher relative abundance of members of the Gammaproteobacteria, Actinobacteria, and Firmicutes, and a lower relative abundance of members of the Alphaproteobacteria and Bacteroidetes. Plant beneficial bacteria like Sphingomonas spp. and Rhizobium spp. occurred in significantly lower relative abundance in leaf samples of warmed plots. In contrast, several members of the Enterobacteriaceae, especially Enterobacter and Erwinia, and other potential plant or human pathogenic genera such as Acinetobacter and insect-associated Buchnera and Wolbachia spp. occurred in higher relative abundances in the phyllosphere samples from warmed plots. This study showed for the first time the long-term impact of moderate (+2°C) surface warming on the phyllosphere microbiota on plants. A reduction of beneficial bacteria and an enhancement of potential pathogenic bacteria in the phyllosphere of plants may indicate that this aspect of the ecosystem which has been largely neglected up till now, can be a potential risk for pathogen transmission in agro-ecosystems in the near future.
-
Keywords: |
temperature |
grassland |
warming |
Heating |
Air temperature |
stability |
Global warming |
elevated temperature |
Epiphytic Microbial Community |
long-term response |
population dynamic |
species composition |
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.
-
log in to download
-
link
-
view metadata
-
DOI: https://doi.org/10.1016/j.soilbio.2018.05.005
-
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.
-
Keywords: |
eCO2 |
climate change |
grassland |
Giessen FACE |
C sequestration |
SOC dynamics |
soil structure |
subsoil |
carbon cycle |
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.
-
log in to download
-
link
-
view metadata
-
DOI: 10.1099/ijsem.0.001326
-
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).
-
Keywords: |
grassland |
Epiphytic Microbial Community |
grassland ecology |
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.
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.
-
link
-
view metadata
-
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.
-
Keywords: |
elevated CO2 |
grassland |
plant growth |
uncertainty analysis |
coupled model |
water balance |
Seibert, R.; Grünhage, L.; Müller, C.; Otte, A. & Donath, T.W. (2018): Raised atmospheric CO2 levels affect soil seed bank composition of temperate grasslands. Journal of Vegetation Science 30, 86-97
DOI: http://dx.doi.org/10.1111/jvs.12699.
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.
Grünhage, L.; Kammann, C. & Moser, G. (2016-01-07). GiFACE Sampling Design. Presented at Internal Presentation, Giessen.
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.