Unraveling the physical and physiological basis for the solar- induced chlorophyll fluorescence and photosynthesis  relationship using continuous leaf and canopy  measurements of a corn crop

Yang, Peiqi; van der Tol, Christiaan; Campbell, Petya K. E.; Middleton, Elizabeth M.

doi:https://doi.org/10.5194/bg-18-441-2021

Articles | Volume 18, issue 2

https://doi.org/10.5194/bg-18-441-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-18-441-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 2

Research article

|

20 Jan 2021

Research article |

| 20 Jan 2021

Unraveling the physical and physiological basis for the solar- induced chlorophyll fluorescence and photosynthesis relationship using continuous leaf and canopy measurements of a corn crop

Peiqi Yang, Christiaan van der Tol, Petya K. E. Campbell, and Elizabeth M. Middleton

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Final revised paper (published on 20 Jan 2021)
Supplement to the final revised paper
Preprint (discussion started on 08 Sep 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of 'Unravelling...' by P. Yang', Anonymous Referee #1, 29 Sep 2020
- AC1: 'Response to Reviewer #1', Peiqi Yang, 02 Nov 2020
- AC4: 'Revised manuscript with the changes highlighted', Peiqi Yang, 09 Nov 2020
RC2: 'Review report: "Unravelling the physical and physiological basis for the solar-induced chlorophyll fluorescence and photosynthesis relationship" by Peiqi Yang et al.', Anonymous Referee #2, 26 Oct 2020
- AC2: 'Response to Reviewer #2', Peiqi Yang, 02 Nov 2020
SC1: 'Review for “Unravelling the physical and physiological basis for the solar-induced chlorophyll fluorescence and photosynthesis relationship” by Yang et al.', Kaiyu Guan, 27 Oct 2020
- AC3: 'Response to Dr KaiYu Guan', Peiqi Yang, 02 Nov 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (07 Nov 2020) by Alexandra Konings

Dear Dr. Yang and co-authors,

As you have seen by now, your work was assessed by three reviews. All three of the reviewers are generally encouraging of this work and note that it is potentially an important contribution to the literature on the SIF-GPP relationship. However, the number of requested clarifications and comments is extensive, so I recommend revising with major revisions.

Based on your author responses submitted so far, here are a few things to keep in mind as you revise the manuscript:
1) In your author responses, you have addressed a number of the requests for clarification by the three reviewers only by providing clarifying statements in the review document - in most cases, these requests for clarification should also lead to changes in the text to make sure the text is made more clear for the readers.

2) When you send a revised manuscript with response to reviewer documents, please do not just say that you have clarified something in the text as you do in the responses you have pointed to so far, but include the actual new text in your response to reviewers document. Otherwise it is quite difficult to determine that you have actually satisfactorily addressed the comments.

3) Additionally, please make sure the abstract is consistent with the most important points in the text. For example, you plan to show the diurnal relationship between phi F and phi P only in the supplement, but this is still highlighted as a key finding in your abstract.

4) Lastly, please do pay attention to Prof. Guan's last comment. While there is nothing wrong with arguing that a reviewer suggestion is outside the scope of your manuscript, the underlying comment that the leaf-level and canopy-level results are not sufficiently well-integrated with each other in your analysis should still be addressed in your response, not just the suggestion to run SCOPE. Several other comments by Dr. Guan (#'s 5 and 8, for example) are also only partially addressed in the current author responses.

Please keep the above comments in mind as you prepare your revised manuscript and a final response document. I look forward to receiving the revisions.

Best regards,
Alex Konings

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AR by Peiqi Yang on behalf of the Authors (09 Nov 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Nov 2020) by Alexandra Konings

RR by Anonymous Referee #1 (23 Nov 2020)

Suggestions for revision or reasons for rejection

Reviewer comment, revised paper ‘Unravelling the physical..’ by Yang et al.

I very much enjoyed reading the revised version of the paper. I also think that the authors have done adequate job in answering the comments and the revision.

I liked the answer to Reviewer #2 comment (lines 277-279) and would like to see the context also in the manuscript (right now I didn’t notice that).

One thing that I was thinking during reading, was that very much of this work is based on correlation values, but their significance (p-value) is not addressed at all. The authors could consider adding that.

Below some minor comments, that the authors might want to address.

Minor comments (the line numbers refer to the version with the track changes):

l. 32: Need to add reference about the influence of carbon uptake on understanding of climate.

l. 35: Now you added ‘of net carbon flux’, but don’t mention that GPP can be further estimated from the net carbon flux.

l. 35: It’s not actually ‘carbon flux’, but mainly the uptake of carbon, not the net flux.

l. 43: Would these two cases be examples, ‘e.g’ and not the whole research done on this?

l. 45: Why not add references, there are plenty of publications that looked into this?

l. 63: This Guanter study is based on remote sensing whereas the following paragraph deals with in-situ studies. I’d make this distinction now clearer and do you somewhere then also comment, how your finding of this study also possibly contribute to satellite-based observations or if the message from the canopy level is directly applicable also to those?

l. 101: Not clear what you mean by ‘because of the importance of...’. I don’t understand now how that makes study of corn more relevant than other species.

l. 128: NEP: often the instantaneous flux measurement is called NEE and the integrated annual value NEP. You might consider here using NEE instead NEP.

l. 131: Where was the FloxBox sensor pointing at and what is its field of view? Was it towards a sunlit area of the vegetation throughout the day?

l. 159: Why did you exclude densely clouded days?

l. 232: I’m surprised you call here Ci a parameter. Based on the first sentence of the paragraph it would sound like a variable influencing photosynthetic lue…

l. 235: Did you do any calculations for the significance of the partial correlation?

l. 295: Now just Fig. 4. Same in line 305.

l. 295 paragraph/ l. 320: In the first paragraph you say there were only little changes during nighttime and on the next part you mention noticeable changes. Is this contradictory?

l. 305, paragraph: You only talk about the dynamics in response to light levels. Is there any connection with the absolute light levels between the values reached? Or should that even be linked? In some instances the (sunlit) FiiP goes lower with higher light levels, but it’s not obvious if this is really taking place… You go more into this in the next section. Maybe you could also say something already here.

l. 334: Here the color is denoted as gold, in the caption as yellow.

l. 378: Negatively correlated with each other?

l. 391: ‘moderately correlated’: at light levels above 500 µmol m-2 s-1, or do you mean to dump here together the negative correlation at low light levels and positive correlation at high light levels?

l. 418: ‘the simulations’?

l. 495: What is ‘moderately strong’? You could add here the number.

l. 592: ‘Much larger’ than what? Than the shaded?

l. 594-595: Sorry, not sure I get it. Dr. Guan also raised this point (#7) and in the reply you discuss this, but it hasn’t made it to the manuscript. This point could be clarified.

l. 603-605: But you removed the cloudy days, so can you really see this in your data?

l. 623: Ps or Psun?

l. 676: Sorry, how did you come to equation 13?

l. 689: ‘better correlated with Ftot than F’?

Table 2: In the caption you could mention that it is in the first line that you have the correlation coefficient.

Table 3: You haven’t mentioned in the caption the meaning of the value in bold. Are these just high correlations? You could make bold the values that have a significant correlation (small p value).

Fig 4, caption: in my copy it seems to be blue solid lines instead of dashed (as mentioned in the caption).

Fig. 8. The first value is on top of the y-axis. It would be recommended to extend the scale of x-axis, so that this doesn’t happen.

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RR by Anonymous Referee #2 (28 Nov 2020)

ED: Publish subject to minor revisions (review by editor) (05 Dec 2020) by Alexandra Konings

AR by Peiqi Yang on behalf of the Authors (09 Dec 2020) Author's response Manuscript

ED: Publish as is (12 Dec 2020) by Alexandra Konings

AR by Peiqi Yang on behalf of the Authors (12 Dec 2020) Manuscript

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Short summary

Solar-induced chlorophyll fluorescence (SIF) has the potential to facilitate the monitoring of photosynthesis from space. This study presents a systematic analysis of the physical and physiological meaning of the relationship between fluorescence and photosynthesis at both leaf and canopy levels. We unravel the individual effects of incoming light, vegetation structure and leaf physiology and highlight their joint effects on the relationship between canopy fluorescence and photosynthesis.