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| Titel |
Bark vegetation contributes to nitrous oxide (N2O) deposition by mature beech trees |
| VerfasserIn |
Katerina Machacova, Martin Maier, Katerina Svobodova, Friederike Lang, Otmar Urban |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143540
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| Publikation (Nr.) |
 EGU/EGU2017-7270.pdf |
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| Zusammenfassung |
| Nitrous oxide (N2O) contributes to the acceleration of the greenhouse effect. Accordingly,
there is an urgent need to investigate the natural capability of forest ecosystems to exchange
N2O with the atmosphere. While the soils of temperate forests were shown to be a significant
natural source of N2O, trees have been so far overlooked in the forest N2O inventories. Trees
are known, however, to emit this gas, especially at very high N2O concentration in
soil.
We determined the N2O fluxes in mature beech trees (Fagus sylvatica) in two upland
mountain forests (White Carpathians, CZ; Black Forest, DE) with predominant soil N2O
uptake. To understand these fluxes, N2O exchange in photoautotrophic organisms associated
with beech stems (lichens, mosses, and algae) was further investigated under laboratory
conditions. Fluxes were measured in situ in June and July 2015 using static chamber systems
followed by chromatographic and photo-acoustic analyses of N2O concentration
changes.
In both forests studied, all beech stems deposited N2O from the atmosphere. Such
consistent uptake of N2O by stems represents a novel and unique finding which is in the
contrast to current limited studies presenting trees as N2O emitters. The mean stem
deposition rates were significantly higher in the White Carpathians (-3.8 μg N2O m−2 stem
area h−1) than in the Black Forest (-2.3 μg N2O m−2 h−1). The forest floor was a strong sink
for N2O (White Carpathians: -111, Black Forest: -81 μg N2O m−2 soil area h−1). The N2O
concentration profiles within the soil did not identify any apparent production or consumption
processes.
Photoautotrophic organisms (lichens, mosses, and algae), largely associated with the bark
of studied trees, were collected for further analyses. The detailed incubation experiments
revealed that all sampled organisms deposited N2O under the conditions of full rehydration
and air temperature of 25˚ C. Their deposition rates per unit area were in the same order of
magnitude as compared to stem deposition rates measured under the field conditions.
Specifically, it was -1.3, -2.0, and -1.8 μg N2O m−2 h−1 for algae, lichens, and mosses,
respectively.
Therefore, it seems that bark vegetation is at least co-responsible for the observed unique
deposition of N2O by beech trees.
Acknowledgement
This research was supported by the Czech Academy of Sciences and the German
Academic Exchange Service (project DAAD-15-03), the Czech Science Foundation
(17-18112Y), National Programme for Sustainability I (LO1415), CzeCOS (LM2015061) and
DFG project (MA 5826/2-1). We thank Marek Jakubik, Sinikka Paulus, Ellen Halaburt and
Sally Haddad for technical and field support. |
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