The effect of elevated atmospheric CO2 concentration on gross nitrogen dynamics, plant N-uptake and microbial community dynamics in a permanent grassland
Final Report Abstract
The overall goal of this study was to understand the long-term effects of eCO2 and carbon input on microbial community composition and activity as well as the associated nitrogen dynamics and plant N uptake to explain the doubling of N2O production under eCO2 in the Giessen FACE study on permanent grassland. To find the reasons for the doubling of N2O emissions under eCO2 (i) the soil microbial community structure in all six FACE rings was inventoried, (ii) the N cycle was studied, (iii) a field pulse labelling experiment was conducted to assess the microbial activity differences and (iv) an incubation study at two different temperatures should show possible temperature dependence of soil N transformation processes. No significant differences in the microbial community structure between eCO2 and aCO2 rings occurred. Small differences between all rings were best explained by spatial distance and similarity of soil moisture conditions between the ring pairs. The progressive nitrogen limitation hypothesis that reduced N availability under eCO2 influenced N transformations could not be confirmed, because new results revealed that high lateral soil water flows caused high N inputs into the studied grassland which therefore is apparently not N limited system. N2O emission peaks during the plant growth periods contributed most to the doubling of N 2O emissions and these events were linked to differences in the soil water content due to different evapotranspiration between eCO2 and aCO2. During the field pulse labelling experiment the N2O emission difference between eCO2 and aCO2 was best explained by a shift in the ratio of transcriptional activation of the functional genes nosZ/(nirK+nirS) presumably causing an unbalanced enzyme activity within the steps of denitrification. This shift caused a significantly increased production of N2O because the N2/N2O ratio of denitrification changed. The soil incubation study at 10° and 19°C revealed no temperature sensitivity of N transformation processes relevant for higher N2O emissions under eCO2.
Publications
- (2014) Effect of eCO2 on microbial communities involved in N cycling in soils. 19th European Nitrogen Cycle Meeting, Ghent, Belgium
Brenzinger K
- (2014) Seasonal dynamics of soil CO2 efflux under elevated atmospheric CO2. European Geoscience Union General Assembly. Vienna, Austria. Geophysical Research Abstracts . Vol. 16, EGU2014-3968
Keidel L, Moser G, Kammann C, Grünhage L, Müller C
(See online at https://dx.doi.org/10.1111/gcb.13713) - (2014) The effect of elevated atmospheric CO2 concentration on gross nitrogen and carbon dynamics in a permanent grassland: A field pulse-labeling study. European Geoscience Union General Assembly. Vienna, Austria. Geophysical Research Abstracts, Vol. 16, EGU2014-3949
Moser G, Gorenflo A, Keidel L, Brenzinger K, Elias D, McNamara N, Maček I, Vodnik D, Braker G, Schimmelpfennig S, Gerstner J, Müller C
- (2015) Response of active microbial communities involved in N-cycling in soils to eCO2 during fertilization. 20th European Nitrogen Cycle Meeting, Aberdeen, UK
Brenzinger K, Moser G, Gorenflo A, Keidel L, Müller C, Braker G
- (2015) Tracing changes in N transformations in a permanent grassland under elevated atmospheric CO 2. European Geoscience Union General Assembly. Vienna, Austria. Geophysical Research Abstracts 17: EGU2015-1482
Moser G, Gorenflo A, Keidel L, Brenzinger K, Elias D, McNamara N, Maček I, Vodnik D, Braker G, Schimmelpfennig S, Gerstner J, Müller C
- (2015) Tracing changes of N 2O emission pathways in a permanent grassland under elevated atmospheric CO 2 concentrations . European Geoscience Union General Assembly. Vienna, Austria. Geophysical Research Abstracts 17: EGU2015-1576
Gorenflo A, Moser G, Keidel L, Brenzinger K, Elias D, McNamara N, Maček I, Vodnik D, Braker G, Schimmelpfennig S, Gerstner J, Müller C
- (2016) Are microbial N transformation rates in a permanent grassland soil after 17 years of elevated atmospheric CO2 sensitive to soil temperature? European Geoscience Union General Assembly. Vienna, Austria. Geophysical Research Abstracts 18: EGU2016-14079-1
Moser G, Gorenflo A, Brenzinger K, Clough T, Braker G, Müller C
- (2016) Organic phosphorus mineralisation in a temperate grassland soil under elevated atmospheric carbon dioxide concentrations. EGU General Assembly, Vienna, Austria. Geophysical Research Abstracts 18: EGU2016-8031
Jarosch, K A, Andresen, L C, Gorenflo, A, Müller, C, Frossard, E, Bünemann, E K
- (2016) Response of active microbial communities involved in N-cycling in soils to eCO2 during fertilization. FACEing the Future - Food Production and Ecosystems, University of Giessen, Germany
Brenzinger K, Moser G, Gorenflo A, Keidel L, Müller C, Braker G
