Evaluation of simulated ozone effects in forest ecosystems against biomass damage estimates from fumigation experiments

Franz, Martina; Alonso, Rocio; Arneth, Almut; Büker, Patrick; Elvira, Susana; Gerosa, Giacomo; Emberson, Lisa; Feng, Zhaozhong; Le Thiec, Didier; Marzuoli, Riccardo; Oksanen, Elina; Uddling, Johan; Wilkinson, Matthew; Zaehle, Sönke

doi:https://doi.org/10.5194/bg-15-6941-2018

Articles | Volume 15, issue 22

https://doi.org/10.5194/bg-15-6941-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-15-6941-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 22

Research article

|

21 Nov 2018

Research article |

| 21 Nov 2018

Evaluation of simulated ozone effects in forest ecosystems against biomass damage estimates from fumigation experiments

Martina Franz, Rocio Alonso, Almut Arneth, Patrick Büker, Susana Elvira, Giacomo Gerosa, Lisa Emberson, Zhaozhong Feng, Didier Le Thiec, Riccardo Marzuoli, Elina Oksanen, Johan Uddling, Matthew Wilkinson, and Sönke Zaehle

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Final revised paper (published on 21 Nov 2018)
Preprint (discussion started on 27 Jul 2018)

Interactive discussion

Status: closed

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

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RC1: 'Review on bg-2018-358', Anonymous Referee #1, 26 Aug 2018
- AC1: 'Answers to Anonymous Referee \# 1', Martina Franz, 05 Sep 2018
RC2: 'Review comments by Marcus Schaub, Maxime Cailleret and Marco Ferretti', Marcus Schaub, 06 Sep 2018
- AC2: 'Reply to Review comments by Marcus Schaub, Maxime Cailleret and Marco Ferretti', Martina Franz, 13 Sep 2018

Peer-review completion

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

ED: Reconsider after major revisions (24 Sep 2018) by Martin De Kauwe

Dear Authors,

Many thanks for your comments and responses to the reviewer comments. Both reviewers were positive, and I concur with their assessment of your manuscript. Please revise the manuscript along the lines you have outlined, providing a point-by-point response to show how you've changed the manuscript.

Please give particular attention to ensuring that you more fully addressed the comments of reviewer #1 with respect to the top of canopy dosage and variation with depth through the canopy. Whilst I found the authors responses satisfactory, I wonder how much effort it would be to test an alternative assumption? If only to demonstrate the sensitivity to an alternative assumption? Alternatively, some space could be dedicated to this in the discussion. In addition, please pay particular to reviewer #2, where they ask about mature vs young trees and species-specific relationships. These questions strike me as interesting points to form a discussion around future extensions of your work.

In addition to their comments, could I please ask you to:

- Abstract: define Vcmax

- Pg 4: where you describe how the labile non-structural pool buffers growth, it strikes me as important for the reader to get a sense of what sort of time-scale this may impose on any direct impact of ozone on leaf-photosynthesis vs. realised growth. Days? Weeks? Months?

- Pg 5: Where you refer to the CUOY being calculated by summation over all layers and then refer to Franz et al. 2017. Is there further detail that the reader should see here? If it is simply summation, then perhaps simply cite Franz? As written it implies that there is additional insight here and that should either be presented here or clarified.

- Pg 6, line 25: why didn't they match well? Could this point be developed/shown? My reading of the manuscript is that this is this what is referred to in Figure 1? If so, could the authors explain to the reader that they will address this in the results? My reading of the methods is that it is simply asserted to be true, but I may have missed the explanation...

- Equation 6, what is n?

- Fig 2: CUOY not CUOy.

- Page 12, line 10: This statement is true so long as the canopy is simulated to be estimated via the Vcmax limitation? This would change in different scenarios (i.e. if the canopy was Jmax limited) and I think this point should be clarified for the reader. Currently it (wrongly - in my opinion) implies that a model would get the same result if they applied the function to Vcmax or An.

Best wishes,

Martin

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AR by Martina Franz on behalf of the Authors (16 Oct 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (17 Oct 2018) by Martin De Kauwe

RR by Bin Wang (19 Oct 2018)

RR by Marcus Schaub (30 Oct 2018)

Suggestions for revision or reasons for rejection

We acknowledge the author’s efforts of adding clarifications to the manuscript and considering our comments. The quality of the manuscript has considerably improved and – in our opinion – is ready to be published after addressing the following points:
(i) Title: The title “Evaluation of simulated biomass damage in forest ecosystems induced by ozone against observation-based estimates” is true when only the part related to the experiments with young trees is concerned. Mature trees are simulated, not actually observed. We therefore suggest to change the title accordingly. We consider this as an important point as the title is not a minor element and will influence the perception and how the manuscript will be received.
(ii) Young vs. mature trees: While it is perfectly justified to show the impact of the different response functions on the possible outcomes of seedlings experiment, extrapolation to forest ecosystem remains a strong simplification. We suggest that authors should clearly state that they use dose-response relationship derived from experiments with young trees for their evaluations regarding mature trees, assuming such relationships hold valid, but that they are well aware this may not be the case. In their new discussion paragraph (p. 19, ll. 9-13) they may also suggest the possible consequences of this assumption.
(iii) It is true that the manuscript deals with only one part of the entire EMEP approach. Nevertheless, the risk evaluation relies very much on the dose-response functions. We still believe that the authors should comment on possible, related consequences of their findings in this respect.
(iv) Throughout the manuscript, the authors used the terms “young trees”, “cuttings”, “saplings”, “seedlings” and “small trees” to describe the experimental trees. We suggest to bring in some consistency by using only e.g. young trees.
Specific comments:
Page 1, line 10: delete “field” in “…against field data …” as this is misleading. Data are from experiments not from field observations.
Page 1, line 11: add “… experiments conducted with young trees from European trees species …”
Page 1, line 12: delete “simulated” in “… functions lead to simulated whole-tree …” as this is redundant; it is clear that functions lead to simulated results.
Page 3, line 3: replace small trees by young trees (see comment iv)
Page 8, line 17: cuttings? (see comment iv)
Page 19, line 27: correct “Whether the simulation of injury … can indeed be transferred to adult trees or not to yield realistic …”

Referee Report: PDF

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ED: Publish subject to minor revisions (review by editor) (31 Oct 2018) by Martin De Kauwe

AR by Martina Franz on behalf of the Authors (04 Nov 2018) Author's response Manuscript

ED: Publish as is (05 Nov 2018) by Martin De Kauwe

AR by Martina Franz on behalf of the Authors (06 Nov 2018)

Short summary

Four published ozone damage functions previously used in terrestrial biosphere models were evaluated regarding their ability to simulate observed biomass dose–response relationships using the O-CN model. Neither damage function was able to reproduce the observed ozone-induced biomass reductions. Calibrating a plant-functional-type-specific relationship between accumulated ozone uptake and leaf-level photosynthesis did lead to a good agreement between observed and modelled ozone damage.