Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations
The closed chamber technique is widely used to measure the exchange of methane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured g...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2016-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/903/2016/bg-13-903-2016.pdf |
| _version_ | 1819156738839937024 |
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| author | N. Pirk M. Mastepanov F.-J. W. Parmentier M. Lund P. Crill T. R. Christensen |
| author_facet | N. Pirk M. Mastepanov F.-J. W. Parmentier M. Lund P. Crill T. R. Christensen |
| author_sort | N. Pirk |
| collection | DOAJ |
| description | The closed chamber technique is widely used to measure the exchange of
methane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) from terrestrial
ecosystems. There is, however, large uncertainty about which model should be
used to calculate the gas flux from the measured gas concentrations. Due to
experimental uncertainties the simple linear regression model (first-order
polynomial) is often applied, even though theoretical considerations of the
technique suggest the application of other, curvilinear models.
High-resolution automatic chamber systems which sample gas concentrations
several hundred times per flux measurement make it possible to resolve the
curvilinear behavior and study the information imposed by the natural
variability of the temporal concentration changes. We used more than 50 000
such flux measurements of CH<sub>4</sub> and CO<sub>2</sub> from five field sites
located in peat-forming wetlands ranging from 56 to 78° N to
quantify the typical differences between flux estimates of different models.
In addition, we aimed to assess the curvilinearity of the concentration time
series and test the general applicability of curvilinear models. Despite
significant episodic differences between the calculated flux estimates, the
overall differences are generally found to be smaller than the local flux
variability on the plot scale. The curvilinear behavior of the gas
concentrations within the chamber is strongly influenced by wind-driven
chamber leakage, and less so by changing gas concentration gradients in the
soil during chamber closure. Such physical processes affect both gas species
equally, which makes it possible to isolate biochemical processes affecting
the gases differently, such as photosynthesis limitation by chamber headspace
CO<sub>2</sub> concentrations under high levels of incoming solar radiation. We
assess the possibility to exploit this effect for a partitioning of the net
CO<sub>2</sub> flux into photosynthesis and ecosystem respiration as an example
of how high-resolution automatic chamber measurements could be used for
purposes beyond the estimation of the net gas flux. This shows that while
linear and curvilinear calculation schemes can provide similar net fluxes,
only curvilinear models open additional possibilities for high-resolution
automatic chamber measurements. |
| first_indexed | 2024-12-22T15:57:39Z |
| format | Article |
| id | doaj.art-54333a28e1bd4e00829360d244b99dba |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-22T15:57:39Z |
| publishDate | 2016-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-54333a28e1bd4e00829360d244b99dba2022-12-21T18:20:45ZengCopernicus PublicationsBiogeosciences1726-41701726-41892016-02-0113490391210.5194/bg-13-903-2016Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrationsN. Pirk0M. Mastepanov1F.-J. W. Parmentier2M. Lund3P. Crill4T. R. Christensen5Department of Physical Geography and Ecosystem Science, Lund University, Lund, SwedenDepartment of Physical Geography and Ecosystem Science, Lund University, Lund, SwedenDepartment of Physical Geography and Ecosystem Science, Lund University, Lund, SwedenDepartment of Physical Geography and Ecosystem Science, Lund University, Lund, SwedenDepartment of Geological Sciences, Stockholm University, Stockholm, SwedenDepartment of Physical Geography and Ecosystem Science, Lund University, Lund, SwedenThe closed chamber technique is widely used to measure the exchange of methane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the simple linear regression model (first-order polynomial) is often applied, even though theoretical considerations of the technique suggest the application of other, curvilinear models. High-resolution automatic chamber systems which sample gas concentrations several hundred times per flux measurement make it possible to resolve the curvilinear behavior and study the information imposed by the natural variability of the temporal concentration changes. We used more than 50 000 such flux measurements of CH<sub>4</sub> and CO<sub>2</sub> from five field sites located in peat-forming wetlands ranging from 56 to 78° N to quantify the typical differences between flux estimates of different models. In addition, we aimed to assess the curvilinearity of the concentration time series and test the general applicability of curvilinear models. Despite significant episodic differences between the calculated flux estimates, the overall differences are generally found to be smaller than the local flux variability on the plot scale. The curvilinear behavior of the gas concentrations within the chamber is strongly influenced by wind-driven chamber leakage, and less so by changing gas concentration gradients in the soil during chamber closure. Such physical processes affect both gas species equally, which makes it possible to isolate biochemical processes affecting the gases differently, such as photosynthesis limitation by chamber headspace CO<sub>2</sub> concentrations under high levels of incoming solar radiation. We assess the possibility to exploit this effect for a partitioning of the net CO<sub>2</sub> flux into photosynthesis and ecosystem respiration as an example of how high-resolution automatic chamber measurements could be used for purposes beyond the estimation of the net gas flux. This shows that while linear and curvilinear calculation schemes can provide similar net fluxes, only curvilinear models open additional possibilities for high-resolution automatic chamber measurements.http://www.biogeosciences.net/13/903/2016/bg-13-903-2016.pdf |
| spellingShingle | N. Pirk M. Mastepanov F.-J. W. Parmentier M. Lund P. Crill T. R. Christensen Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations Biogeosciences |
| title | Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations |
| title_full | Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations |
| title_fullStr | Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations |
| title_full_unstemmed | Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations |
| title_short | Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations |
| title_sort | calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations |
| url | http://www.biogeosciences.net/13/903/2016/bg-13-903-2016.pdf |
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