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Overestimation of closed-chamber soil CO2 effluxes at low atmospheric turbulence

Andreas Brændholt, Klaus Steenberg Larsen, Andreas Ibrom, Kim Pilegaard
2017 Biogeosciences  
<p><strong>Abstract.</strong> Soil respiration (<i>R</i><sub>s</sub>) is an important component of ecosystem carbon balance, and accurate quantification of the diurnal and seasonal variation of <i>R</i><sub>s</sub> is crucial for a correct interpretation of the response of <i>R</i><sub>s</sub> to biotic and abiotic factors, as well as for estimating annual soil CO<sub>2</sub> efflux rates.<br><br> In this study, we measured <i>R</i><sub>s</sub> hourly for 1 year by automated closed chambers in
more » ... temperate Danish beech forest. The data showed a clear diurnal pattern of <i>R</i><sub>s</sub> across all seasons with higher rates during night-time than during daytime. However, further analysis showed a clear negative relationship between flux rates and friction velocity (<i>u</i><sub>∗</sub>) above the canopy, suggesting that <i>R</i><sub>s</sub> was overestimated at low atmospheric turbulence throughout the year due to non-steady-state conditions during measurements. Filtering out data at low <i>u</i><sub>∗</sub> values removed or even inverted the observed diurnal pattern, such that the highest effluxes were now observed during daytime, and also led to a substantial decrease in the estimated annual soil CO<sub>2</sub> efflux.<br><br> By installing fans to produce continuous turbulent mixing of air around the soil chambers, we tested the hypothesis that overestimation of soil CO<sub>2</sub> effluxes during low <i>u</i><sub>∗</sub> can be eliminated if proper mixing of air is ensured, and indeed the use of fans removed the overestimation of <i>R</i><sub>s</sub> rates during low <i>u</i><sub>∗</sub>. Artificial turbulent air mixing may thus provide a method to overcome the problems of using closed-chamber gas-exchange measurement techniques during naturally occurring low atmospheric turbulence conditions. Other possible effects from using fans during soil CO<sub>2</sub> efflux measurements are discussed. In conclusion, periods with low atmospheric turbulence may provide a significant source of error in <i>R</i><sub>s</sub> rates estimated by the use of closed-chamber techniques and erroneous data must be filtered out to obtain unbiased diurnal patterns, accurate relationships to biotic and abiotic factors, and before estimating <i>R</i><sub>s</sub> fluxes over longer timescales.</p>
doi:10.5194/bg-14-1603-2017 fatcat:oyl5oezeujcpfemv2omhg6bpay

Overestimation of closed chamber soil CO2 effluxes at low atmospheric turbulence

Andreas Brændholt, Klaus Steenberg Larsen, Andreas Ibrom, Kim Pilegaard
2016 Biogeosciences Discussions  
Soil respiration (<i>R</i><sub>s</sub>) is an important component of ecosystem carbon balance and accurate quantification of the diurnal and seasonal variation of <i>R</i><sub>s</sub> is crucial for correct interpretation of the response of <i>R</i><sub>s</sub> to biotic and abiotic factors, as well as for estimating annual soil CO<sub>2</sub> efflux rates. <br><br> In this study, we measured <i>R</i><sub>s</sub> hourly for one year by automated closed chambers in a temperate Danish beech
more » ... . The data showed a clear diurnal pattern of <i>R</i><sub>s</sub> across all seasons with higher rates during night-time than during day-time. However, further analysis showed a clear negative relationship between flux rates and friction velocity (<i>u</i><sub>∗</sub>) above the canopy, suggesting that <i>R</i><sub>s</sub> was overestimated at low atmospheric turbulence throughout the year due to non-steady state conditions during measurements. Filtering out data at low <i>u</i><sub>∗</sub> values removed or even inverted the observed diurnal pattern, such that the highest effluxes were now observed during day-time, and also led to a substantial decrease in the estimated annual soil CO<sub>2</sub> efflux. <br><br> By installing fans to produce continuous turbulent mixing of air around the soil chambers, we tested the hypothesis that overestimation of soil CO<sub>2</sub> effluxes during low <i>u</i><sub>∗</sub> can be eliminated if proper mixing of air is ensured, and indeed the use of fans removed the overestimation of <i>R</i><sub>s</sub> rates during low <i>u</i><sub>∗</sub>. Artificial turbulent air mixing may thus provide a method to overcome the problems of using closed chamber gas exchange measurement techniques during naturally occurring low atmospheric turbulence conditions. Other possible effects from using fans during soil CO<sub>2</sub> efflux measurements are discussed. In conclusion, periods with low atmospheric turbulence may provide a significant source of error in <i>R</i><sub>s</sub> rates estimated by the use of closed chamber techniques and erroneous data must be filtered out to obtain unbiased diurnal patterns, accurate relationships to biotic and abiotic factors, and before estimating <i>R</i><sub>s</sub> fluxes over longer time scales.
doi:10.5194/bg-2016-490 fatcat:lds5b5vvgvew5gqvkokwbh75ua

Environmental performance of gasified willow from different lands including land-use changes

Koldo Saez de Bikuña, Michael Zwicky Hauschild, Kim Pilegaard, Andreas Ibrom
2016 GCB Bioenergy  
doi:10.1111/gcbb.12378 fatcat:rmhfb7svmvertowvz72usz3w3u

Changes In Phenology And The Influence On The Carbon Sequestration In A Danish Beech Forest Over 20 Years

Kim Pilegaard, Andreas Ibrom
2017 Zenodo  
Authors Kim Pilegaard, E-mail: kipi@env.dtu.dk Andreas Ibrom, E-mail: anib@env.dtu.dk 6  ... 
doi:10.5281/zenodo.375860 fatcat:s7cy4ekaizebvgwqck3pzryn6a

Soil COS exchange: a comparison of three European ecosystems

Florian Kitz, Felix M. Spielmann, Albin Hammerle, Olaf Kolle, Mirco Migliavacca, Gerardo Moreno, Andreas Ibrom, Dmitrii Krasnov, Steffen M. Noe, Georg Wohlfahrt
2020 Global Biogeochemical Cycles  
COS production in seawater was the highest at shorter wavelengths and decreased with increasing wavelengths (in an investigated range of 280-380 nm) (Zepp & Andreae, 1994) .  ... 
doi:10.1029/2019gb006202 fatcat:avt7w53m5fd2jo4yrjjlfkrguu

Radiation measurements at ICOS ecosystem stations

Arnaud Carrara, Pasi Kolari, Maarten Op de Beeck, Nicola Arriga, Daniel Berveiller, Sigrid Dengel, Andreas Ibrom, Lutz Merbold, Corinna Rebmann, Simone Sabbatini, Penelope Serrano-Ortíz, Sébastien C. Biraud
2018 International Agrophysics  
., 2002; Ibrom et al., 2006; Knohl and Baldocchi, 2008) , thereby increasing the CO2 sink of terrestrial ecosystems (Gu et al., 2003; Roderick 2003, Mercado et al., 2009) .  ... 
doi:10.1515/intag-2017-0049 fatcat:4t4ymb4ouvbpnopegxs7pyp3vu

Combining a Quantum Cascade Laser Spectrometer with an Automated Closed-Chamber System for δ13C Measurements of Forest Soil, Tree Stem and Tree Root CO2 Fluxes

Andreas Brændholt, Andreas Ibrom, Per Ambus, Klaus Steenberg Larsen, Kim Pilegaard
2019 Forests  
Recent advances in laser spectroscopy have allowed for real-time measurements of the 13C/12C isotopic ratio in CO2, thereby providing new ways to investigate carbon cycling in natural ecosystems. In this study, we combined an Aerodyne quantum cascade laser spectrometer for CO2 isotopes with a LI-COR LI-8100A/8150 automated chamber system to measure the δ13C of CO2 during automated closed-chamber measurements. The isotopic composition of the CO2 flux was determined for each chamber measurement
more » ... applying the Keeling plot method. We found that the δ13C measured by the laser spectrometer was influenced by water vapour and CO2 concentration of the sample air and we developed a method to correct for these effects to yield accurate measurements of δ13C. Overall, correcting for the CO2 concentration increased the δ13C determined from the Keeling plots by 3.4‰ compared to 2.1‰ for the water vapour correction. We used the combined system to measure δ13C of the CO2 fluxes automatically every two hours from intact soil, trenched soil, tree stems and coarse roots during a two-month campaign in a Danish beech forest. The mean δ13C was −29.8 ± 0.32‰ for the intact soil plots, which was similar to the mean δ13C of −29.8 ± 1.2‰ for the trenched soil plots. The lowest δ13C was found for the root plots with a mean of −32.6 ± 0.78‰. The mean δ13C of the stems was −30.2 ± 0.74‰, similar to the mean δ13C of the soil plots. In conclusion, the study showed the potential of using a quantum cascade laser spectrometer to measure δ13C of CO2 during automated closed-chamber measurements, thereby allowing for measurements of isotopic ecosystem CO2 fluxes at a high temporal resolution. It also highlighted the importance of proper correction for cross-sensitivity with water vapour and CO2 concentration of the sample air to get accurate measurements of δ13C.
doi:10.3390/f10050432 fatcat:qebusjya7ba4fc5o2ssglm4k6u

Forest production efficiency increases with growth temperature [article]

Alessio Collalti, Andreas Ibrom, Anders Stockmarr, Alessandro Cescatti, Ramdane Alkama, Marcos Fernandez-Martinez, Giorgio Matteucci, Stephen Sitch, Pierre Friedlingstein, Philippe Ciais, Daniel S. Goll, Julia E.M.S. Nabel (+4 others)
2020 biorxiv/medrxiv   pre-print
We present a global analysis of the relationship of forest production efficiency (FPE) to stand age and climate, based on a large compilation of data on gross primary production and either biomass production or net primary production. FPE is important for both forest production and atmospheric carbon dioxide uptake. Earlier findings - FPE declining with age - are supported by this analysis. However, FPE also increases with absolute latitude, precipitation and (all else equal) with temperature.
more » ... he temperature effect is opposite to what would be expected based on the short-term physiological response of respiration rates to temperature. It implies top-down regulation of forest carbon loss, perhaps reflecting the higher carbon costs of nutrient acquisition in colder climates. Current ecosystem models do not reproduce this phenomenon. They consistently predict lower FPE in warmer climates, and are therefore likely to overestimate carbon losses in a warming climate.
doi:10.1101/2020.04.15.042275 fatcat:ukd7wh627zdipjmltduo5t4xj4

Reduction of molecular gas diffusion through gaskets in leaf gas exchange cuvettes by leaf-mediated pores

KRISTINE S. BOESGAARD, TEIS N. MIKKELSEN, HELGE RO-POULSEN, ANDREAS IBROM
2013 Plant, Cell and Environment  
doi:10.1111/pce.12064 pmid:23320654 fatcat:vcqhpkgg7rdodiayhamiokjj3m

Temporal interpolation of land surface fluxes derived from remote sensing – results with an unmanned aerial system

Sheng Wang, Monica Garcia, Andreas Ibrom, Peter Bauer-Gottwein
2020 Hydrology and Earth System Sciences  
The eddy covariance data processing followed the same procedures as in Pilegaard et al. (2011 ), Ibrom et al. (2007 , and Fratini et al. (2012) , i.e. the standard ICOS (Integrated Carbon Observation  ... 
doi:10.5194/hess-24-3643-2020 fatcat:hlpdyrkgrneltpot2kqwc7l5lq

Net carbon ecosystem exchange during 24 years in the Sorø Beech Forest – relations to phenology and climate

Kim Pilegaard, Andreas Ibrom
2020 Tellus: Series B, Chemical and Physical Meteorology  
IBROM  ...  IBROM although the carbon uptake period is increasing, the period with leaves is not.  ...  IBROM  ... 
doi:10.1080/16000889.2020.1822063 fatcat:pg4xrobpnbfq3k2y4kign23ova

Eddy covariance raw data processing for CO2 and energy fluxes calculation at ICOS ecosystem stations

Simone Sabbatini, Ivan Mammarella, Nicola Arriga, Gerardo Fratini, Alexander Graf, Lukas Hörtnagl, Andreas Ibrom, Bernard Longdoz, Matthias Mauder, Lutz Merbold, Stefan Metzger, Leonardo Montagnani (+6 others)
2018 International Agrophysics  
Ibrom, 2008; Mammarella et al., 2009; Nordbo et al., 2014) .  ...  Step 10.3.2: Experimental method (Ibrom et al., 2007a; Fratini et al., 2012) The experimental method firstly described in Ibrom et al. (2007a) and then refined in Fratini et al., 2012 is applied  ... 
doi:10.1515/intag-2017-0043 fatcat:dmzecilp2zgupdej3grq3qgavq

Gas chromatography vs. quantum cascade laser-based N2O flux measurements using a novel chamber design

Christian Brümmer, Bjarne Lyshede, Dirk Lempio, Jean-Pierre Delorme, Jeremy J. Rüffer, Roland Fuß, Antje M. Moffat, Miriam Hurkuck, Andreas Ibrom, Per Ambus, Heinz Flessa, Werner L. Kutsch
2017 Biogeosciences  
thanks are owed to Florian Hackelsperger from the experimental research station of the Institute of Animal Nutrition for technical support during the Braunschweig campaign as well as Kerstin Gilke and Andrea  ... 
doi:10.5194/bg-14-1365-2017 fatcat:3qxao2ttxzaa5h5lpofolvpmde

Surface-atmosphere exchange of ammonia over peatland using QCL-based eddy covariance measurements and inferential modeling

Undine Richter, Christian Brümmer, Frederik Schrader, Christof Ammann, Andreas Ibrom, Christophe R. Flechard, David D. Nelson, Mark Zahniser, Werner L. Kutsch
2016 Atmospheric Chemistry and Physics Discussions  
We thank Jeremy Smith, Jean-Pierre Delorme, as well as Ute Tambor, Andrea Niemeyer, and Daniel Ziehe for excellent technical support and conducting laboratory analyses of denuder and filter samples, respectively  ...  ; Ibrom et al., 2007) , thus avoiding interactions of ammonia with surfaces (Walker et al., 2006; Norman et al., 2009; Ellis et al., 2010) .  ...  Heating the inertial inlet box (at approx. 40 • C) and the anti-adhesive PFA tubing that leads the sample air to the QCL's analyzer cell minimize water condensation or absorption (Massman and Ibrom, 2008  ... 
doi:10.5194/acp-2016-197 fatcat:tatdbolmjffizjgk4i4e3eegfi

Gas chromatography vs. quantum cascade laser-based N2O flux measurements using a novel chamber design

Christian Brümmer, Bjarne Lyshede, Dirk Lempio, Jean-Pierre Delorme, Jeremy J. Smith, Roland Fuß, Antje M. Moffat, Miriam Hurkuck, Andreas Ibrom, Per Ambus, Heinz Flessa, Werner L. Kutsch
2016 Biogeosciences Discussions  
In: Andreae, M.O., Schimel, D.S., Eds. Exchange of trace gases between terrestrial ecosystems and the atmosphere. Chichester: John Wiley and Sons Ltd. pp 721, 1989. Flessa, H.  ... 
doi:10.5194/bg-2016-271 fatcat:y5umfbv4hbdp3ntmdyimjukjda
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