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| Titel |
Potentials and challenges associated with automated closed dynamic chamber measurements of soil CO2 fluxes |
| VerfasserIn |
Carolyn-Monika Görres, Claudia Kammann, Reinhart Ceulemans |
| 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 |
250110526
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| Publikation (Nr.) |
 EGU/EGU2015-10530.pdf |
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| Zusammenfassung |
| Soil respiration fluxes are influenced by natural factors such as climate and soil type, but also
by anthropogenic activities in managed ecosystems. As a result, soil CO2 fluxes show a large
intra- and interannual as well as intra- and intersite variability. Most of the available
soil CO2 flux data giving insights into this variability have been measured with
manually closed static chambers, but technological advances in the past 15 years
have also led to an increased use of automated closed chamber systems. The great
advantage of automated chambers in comparison to manually operated chambers is
the higher temporal resolution of the flux data. This is especially important if we
want to better understand the effects of short-term events, e.g. fertilization or heavy
rainfall, on soil CO2 flux variability. However, the chamber method is an invasive
measurement method which can potentially alter soil CO2 fluxes and lead to biased
measurement results. In the peer-reviewed literature, many papers compare the field
performance and results of different closed static chamber designs, or compare manual
chambers with automated chamber systems, to identify potential biases in CO2 flux
measurements, and thus help to reduce uncertainties in the flux data. However,
inter-comparisons of different automated closed dynamic chamber systems are still
lacking.
Here we are going to present a field comparison of the most-cited automated chamber
system, the LI-8100A Automated Soil Flux System, with the also commercially
available Greenhouse Gas Monitoring System AGPS. Both measurement systems were
installed side by side at a recently harvested poplar bioenergy plantation (POPFULL,
http://uahost.uantwerpen.be/popfull/) from April 2014 until August 2014. The plantation
provided optimal comparison conditions with a bare field situation after the harvest and a
regrowing canopy resulting in a broad variety of microclimates. Furthermore, the plantation
was planted in a double-row system with the row width alternating between 1.50 m and 0.75
m, creating spatial differences in e.g. dry bulk density and soil organic carbon content. The
soil CO2 flux data sets were split into four subsets each characterized by different
environmental conditions, thus presenting different challenges for the measurement
equipment, namely 1) daytime, calm conditions, 2) daytime, windy conditions, 3) nighttime,
calm conditions, and 4) nighttime, windy conditions. In parallel to the chamber
measurements, soil CO2 concentrations were manually measured in the topsoil. Soil CO2
fluxes calculated from this dataset were used as a reference range of soil CO2 fluxes at the
field site.
Funding support: ERC Advanced Grant agreement (# 233366) POPFULL under the EC 7th
Framework Program (FP7/2007-2013), Flemish Hercules Foundation as Infrastructure
contract # ZW09-06, and the Methusalem Program of the Flemish Government. |
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