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| Titel |
Temperature versus plant effects on diel dynamics of soil CO2 production and efflux: a controlled environment study |
| VerfasserIn |
David Reinthaler, Jacques Roy, Damien Landais, Clément Piel, Victor Resco De Dios, Michael Bahn |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111983
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| Publikation (Nr.) |
 EGU/EGU2015-12137.pdf |
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| Zusammenfassung |
| Soil respiration (Rs) is the biggest source of CO2 emitted from terrestrial ecosystems to the
atmosphere. Therefore the understanding of its drivers is of major importance for models of
carbon cycling. Next to temperature as a major abiotic factor, photosynthesis has been
suggested as an important driver influencing diel patterns in Rs. Under natural conditions
it is difficult to disentangle abiotic and biotic effects on soil CO2 production, as
fluctuating light intensity affects both photosynthetic activity and soil temperature.
To analyse individual and combined effects of soil temperature and light on the
dynamics of soil CO2 production and efflux, we performed a controlled environment
study at the ECOTRON facility in Montpellier. The study manipulated temperature
and photosynthetically active radiation independently and was carried out in large
macrocosms, hosting canopies of either a woody (cotton) or a herbaceous (bean) crop.
In each macrocosm membrane tubes had been installed across the soil profile for
continuous measurement of soil CO2 concentrations. In addition, an automated soil
respiration system was installed in each macrocosm, whose data were also used for
validating a model of soil CO2 production and transport based on the concentration
profiles.
Both for cotton and for bean canopies, under conditions of naturally fluctuating
temperature and light conditions, soil CO2 production and efflux followed a clear diel pattern.
Under constantly dark conditions (excluding immediate effects of photosynthesis) and
constant temperature, no significant diel changes in Rs could be observed. Furthermore, soil
CO2 production and efflux did not increase significantly upon exposure of previously
darkened macrocosms to light. Under constant temperature and fluctuating light conditions,
we observed a dampened diel pattern of Rs, which did not match diurnal solar cycles. A
detailed residual analysis accounting for temporal trends in soil moisture suggested a
significant effect of photosynthetically active radiation on Rs in 15 out of 35 cases, but no
such effect in 20 cases. Thus, our study suggests that while effects of photosynthetic plant
activity on diel patterns of soil CO2 production and efflux may occur, they are not
consistent and play a comparatively minor role relative to those of soil temperature. |
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