The effect of drought on dissolved organic carbon (DOC) release from peatland soil and vegetation sources

Ritson, Jonathan P.; Brazier, Richard E.; Graham, Nigel J. D.; Freeman, Chris; Templeton, Michael R.; Clark, Joanna M.

doi:https://doi.org/10.5194/bg-14-2891-2017

Articles | Volume 14, issue 11

https://doi.org/10.5194/bg-14-2891-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-14-2891-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 11

Research article

|

16 Jun 2017

Research article |

| 16 Jun 2017

The effect of drought on dissolved organic carbon (DOC) release from peatland soil and vegetation sources

Jonathan P. Ritson, Richard E. Brazier, Nigel J. D. Graham, Chris Freeman, Michael R. Templeton, and Joanna M. Clark

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Final revised paper (published on 16 Jun 2017)
Supplement to the final revised paper
Preprint (discussion started on 12 Jan 2017)
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: 'Reviewers comments', Anonymous Referee #1, 23 Jan 2017
- AC1: 'Response to anonymous referee #1, posted 23.1.17', Jonathan Ritson, 27 Jan 2017
RC2: 'The effect of drought on dissolved organic carbon (DOC) release from peatland soil and vegetation sources', Anonymous Referee #2, 27 Jan 2017
- AC2: 'Response to reviewer #2', Jonathan Ritson, 27 Feb 2017
RC3: 'Review', Anonymous Referee #3, 31 Jan 2017
- AC3: 'Response to reviewer #3', Jonathan Ritson, 27 Feb 2017

Peer-review completion

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

ED: Reconsider after major revisions (22 Mar 2017) by Peter van Bodegom

AR by Jonathan Ritson on behalf of the Authors (03 Apr 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Apr 2017) by Peter van Bodegom

RR by Anonymous Referee #3 (17 Apr 2017)

Suggestions for revision or reasons for rejection

While the revisions appear to address most of my initial concerns, I still found it difficult to disentangle this study from Ritson et al. 2016. I recognize that there are a number of different analyses between papers but the purpose of both papers seem nearly identical and have many overlapping results. There is a brief section in the Discussion (Lines 424-427) that highlights how Ritson 2016 differed from the current paper as Ritson 2016 extracted DOC from peat that had been exposed to a minimal amount of oxygenation during transport whereas the current study reports on peat exposed to oxygenation. I think the authors should point out this experimental difference early in the Introduction as this is an extremely important difference and the reader needs be aware of it straightaway (to avoid the same confusion I had).

Authors highlight previous studies and define objectives of this new study, but fail to provide hypotheses regarding their choice for peatland vegetation. They do a fine enough job articulating why different plant species should be tested but without hypotheses for expected effects, the experimental design with these specific plant species remains too speculative for justification. Why did the authors choose these three specific vascular plant species? Is there a reason why these particular plant species might affect DOC differently such that they needed to be tested? Use your results from Ritson 2016 to provide hypotheses for the current study. This would also help you rationalize this study as a follow-up to Ritson 2016 and why it would make a valuable addition to the scientific community. Please include hypotheses at the end of the Introduction to address this.

Line 145-147: A potential limitation to this study (and Ritson 2016) is the use of RO treated water to simulate rainfall. Several previous studies on rainfall simulation in peatland experiments utilize “artificial rainwater” with chemistry that matches natural rainwater. Natural (or artificial) rainwater may play a role in DOC quality that cannot be distinguished from this study. Have you considered this?

Line 169: Change “exiting” to “existing”

Line 334: Change “it” to “its”

Line 451-453: It appears that the authors’ ultimate justification is to provide support for catchment management programmes on peatland water table levels. This justification seems to always be mentioned fleetingly and no additional information about these programmes is ever provided. Additional details (either within Intro or Discussion) about these programmes and their effectiveness at managing catchments (i.e., provide specific examples where these have been implemented) and how they can (or have) minimize(d) costs and resources at water treatment plants would be nice to see. In its current form, this justification reads more as an attempt to scale your results without provided sufficient evidence for this rationale.

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RR by Anonymous Referee #2 (28 Apr 2017)

ED: Publish subject to minor revisions (Editor review) (03 May 2017) by Peter van Bodegom

AR by Jonathan Ritson on behalf of the Authors (05 May 2017) Author's response Manuscript

ED: Publish as is (08 May 2017) by Peter van Bodegom

AR by Jonathan Ritson on behalf of the Authors (09 May 2017)

Short summary

Peatlands are a globally important store of carbon; however increased droughts in the future may affect their ability to sequester carbon. Using laboratory simulations we show that droughts, through exposure to oxygen, greatly increase the quantity and alter the quality of dissolved organic carbon (DOC) released from peat. Catchment management which keeps water tables high to limit oxygen exposure is therefore likely to deliver positive water quality outcomes.