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Peer review report 2 On “Tracing the Flow of Carbon Dioxide and Water Vapor between the Biosphere and Atmosphere: A Review of Optical Isotope Techniques and their Application”
Agricultural and Forest Meteorology 201S (2015) 535
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer review report
Peer review report 2 On “Tracing the Flow of Carbon Dioxide and Water Vapor between the Biosphere and Atmosphere: A Review of Optical Isotope Techniques and their Application”
Original Submission Recommendation Minor Revision Comments to Author The manuscript “Optical isotope measurements of carbon dioxide and water vapor: New tools for global change research” by Timothy Griffis reviews the recent developments and applications of optical techniques to determine CO2 and water vapour isotopologue composition. The review describes the measurement principles as well as general features of different optical systems (TDLAS, CRDS, OA-ICOS and FTIR) and focuses on micrometeorological applications of the optical systems (but also tackles underlying physiological mechanisms such as LEDR). The review is timely and I am pretty sure that the scientific community is really awaiting a synthesising paper like this. There are, however, a few points, which I think need be taken into account by the author before the paper can be published 1) The figures show more or less anecdotical results but don’t provide a synthesis of knowledge as I would like to see it in a review like this. It is fully ok to highlight particular important results but it would be also important to bring together information from different sources and extract the essence of the combined data. 2) The description of the biochemical processes involved in LEDR is partially missleading. You refer to the release of 13 C enriched CO2 by PDH (which is fully correct but not really the process involved in the emission of 13 C enriched CO2 of light acclimated leaves directly after darkening); as stated correctly in the LEDR section decarboxylation of malate is the cause of the 13 C isotope enrichment. Maybe the papers of Gessler et al., 2009 and Werner R. et al., 2011 both published in New Phytol might be helpful for brief description of the biochemistry involved in the isotope effects associated with LEDR.
DOI of original article: http://dx.doi.org/10.1016/j.agrformet.2013.02.009. 0168-1923/$ – see front matter http://dx.doi.org/10.1016/j.agrformet.2015.07.202
Some minor points: Line 727: the carbon paper from Wingate et al., 2010 (I think this is the one you are referring to here) is not in the reference list (there is only the 2010 oxyen paper) Line 749: for diel variation in the isotope composition of CO2 you might also want to cite the review of Werner and Gessler published 2011 in Biogeosciences. Line 821; add that the CG model predicts enrichment at the sites of evaporation. Line 894 ff: Could that mean that L is different among leaves from different canopy layers? Line 971 ff: Could other CO2 sources included in the canopy scale assessments but not on the leaf level be a reason for the difference Line 975: The sentence is not clear to me. Line 1020: You refer to phloem or xylem here? Please make this clear. for 13 C labelling you might also want to refer to the new review article of Epron et al published in Tree Phys 2012. Line 1381 “not available” what does that mean? Figure 2 Please give more information in the legend describing the spectral contamination. Figure 6 Not totally clear what is the modelled line - taking steady state or non-steady state. assumptions into account - how were the points determined? needs more information Figure 9 We need more information in the figure legend to really understand what is shown. Figure 8 Is this really needed?. Table 1 WS CRDS comments: but in the text l284 you report strong dependence of d18O from humidity. You, however, also state that precision is not affected by humidity - is that what is meant references to literature to back up the statements would be good. Anonymous Available online 6 August 2015
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer review report
Peer review report 2 On “Tracing the Flow of Carbon Dioxide and Water Vapor between the Biosphere and Atmosphere: A Review of Optical Isotope Techniques and their Application”
Original Submission Recommendation Minor Revision Comments to Author The manuscript “Optical isotope measurements of carbon dioxide and water vapor: New tools for global change research” by Timothy Griffis reviews the recent developments and applications of optical techniques to determine CO2 and water vapour isotopologue composition. The review describes the measurement principles as well as general features of different optical systems (TDLAS, CRDS, OA-ICOS and FTIR) and focuses on micrometeorological applications of the optical systems (but also tackles underlying physiological mechanisms such as LEDR). The review is timely and I am pretty sure that the scientific community is really awaiting a synthesising paper like this. There are, however, a few points, which I think need be taken into account by the author before the paper can be published 1) The figures show more or less anecdotical results but don’t provide a synthesis of knowledge as I would like to see it in a review like this. It is fully ok to highlight particular important results but it would be also important to bring together information from different sources and extract the essence of the combined data. 2) The description of the biochemical processes involved in LEDR is partially missleading. You refer to the release of 13 C enriched CO2 by PDH (which is fully correct but not really the process involved in the emission of 13 C enriched CO2 of light acclimated leaves directly after darkening); as stated correctly in the LEDR section decarboxylation of malate is the cause of the 13 C isotope enrichment. Maybe the papers of Gessler et al., 2009 and Werner R. et al., 2011 both published in New Phytol might be helpful for brief description of the biochemistry involved in the isotope effects associated with LEDR.
DOI of original article: http://dx.doi.org/10.1016/j.agrformet.2013.02.009. 0168-1923/$ – see front matter http://dx.doi.org/10.1016/j.agrformet.2015.07.202
Some minor points: Line 727: the carbon paper from Wingate et al., 2010 (I think this is the one you are referring to here) is not in the reference list (there is only the 2010 oxyen paper) Line 749: for diel variation in the isotope composition of CO2 you might also want to cite the review of Werner and Gessler published 2011 in Biogeosciences. Line 821; add that the CG model predicts enrichment at the sites of evaporation. Line 894 ff: Could that mean that L is different among leaves from different canopy layers? Line 971 ff: Could other CO2 sources included in the canopy scale assessments but not on the leaf level be a reason for the difference Line 975: The sentence is not clear to me. Line 1020: You refer to phloem or xylem here? Please make this clear. for 13 C labelling you might also want to refer to the new review article of Epron et al published in Tree Phys 2012. Line 1381 “not available” what does that mean? Figure 2 Please give more information in the legend describing the spectral contamination. Figure 6 Not totally clear what is the modelled line - taking steady state or non-steady state. assumptions into account - how were the points determined? needs more information Figure 9 We need more information in the figure legend to really understand what is shown. Figure 8 Is this really needed?. Table 1 WS CRDS comments: but in the text l284 you report strong dependence of d18O from humidity. You, however, also state that precision is not affected by humidity - is that what is meant references to literature to back up the statements would be good. Anonymous Available online 6 August 2015