PONE-D-20-34689

Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment

PLOS ONE

Dear Dr. Kretz,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

I agree with reviewers’ comments. The paper could be accepted for publication after addressing reviewers concerns. It would probably require a minor revision. A careful English edition of the main text is desirable. Overall the paper is clear and well-written, but there are several typos and sentences that could be written more clearly. Please note that once the paper is accepted, PLoS One will not send proofs to the authors, so it is important to edit the paper as if it were final.

Please submit your revised manuscript by Feb 27 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Cristina Armas

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide.

Additional Editor Comments:

Beside from comments from reviewers, please check:

There are some “effects” that should be replaced by affect (e.g., L. 36, L. 72 and so on).

Results: Should the units of sediment mass (g) be referred to some area unit (each g m-2)?

Please check the letters included in the Figures so as not to use same letters with different purposes (i.e., results of post-hoc tests and panel “order”.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: General Comments

The article by Dr. Lena Kretz and colleagues entitled ‘Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment’ explore the effect of aboveground vegetation structure on sediment dynamics on floodplains. This research is based on an ex situ experiment undertaken within a flume of 30m long with natural totaly submerged vegetation. The originality of the approach is the consideration of vegetation structural variably (density, height, structural diversity, and leaf pubescence) on fine sedimentation trapping (i) on the plant and (ii) underneath.

Overall the paper is clear and comprehensive. The experiment is well designed and the statistical analyses are adequate and well used. The results are interesting. They bring novelty and improve the way plant effects on sediment dynamics need to be considered in experimental approaches. In particular, they point out the necessity to quantitatively consider the structural diversity (potentially inter- and intra-specific) of plant morphological traits. The discussion is convincing and opens interesting perspectives for future experimental investigations. It would be relevant to add a paragraph in the discussion section related to the fact that the runs were conducted with the same water height. Changes in the hydrogeomorphological parameters (sediment supply and texture, channel slope, discharge) may affect vegetation effects on sediment trapping. Plant structural diversity could possibly explain sediment trapping variability only in a restricted range of discharge and sediment load. I believe you need to acknowledge that point.

Specific comments

L. 36. ‘vegetation biomass positively effects’. Replace ‘effects’ by ‘affects’

L. 44-45. ‘Thus, floodplains are among the most threatened ecosystems worldwide’ The causal linkage with fine sediment dynamics is not obvious. Clarifications are required about why floodplains are to be considered as threatened ecosystems in relation with fine sediment load.

L. 46. How does urbanization of floodplains increase erosion?

L. 71. ‘Plant functional groups’ require a definition from the classical functional trait-based approach (e.g. Garnier, Lavorel, Diaz papers).

L. 75. ‘due to natural variation’. What is the natural variation? Variation of what (genotypic, phenotypic, phenology, habitat conditions…)?

L. 85-86. ‘On the other hand, dense vegetation can cause vertical mixing of the flow and increase turbulence that may change sedimentation patterns’. A vegetation matt with intermediate density can also enhance turbulence and erosion by causing flow divergence around the structures.

L. 105-106. What here is the exact meaning of ‘functionally more diverse vegetation patches (e.g. mixtures of functionally different plant species)’. Functionality (related to sediment trapping? Or to other functions such as photosynthesis if your consider leaf area…) needs to be better defined from the beginning.

L. 112-113. ‘However, we expect that leaf surface structure has no strong effect on sedimentation on the soil surface underneath the vegetation.’ Why? You need to provide a short explanation. Large leafs could increase biomass and thus water blockage effect? But indeed leaf pubescence should not affect underneath sedimentation.

L. 336. Replace (Kretz et al. 2020) by the ref number.

L. 357. Replace (Proulx et al. 2014) by ref number.

Reviewer #2: The authors present an interesting study on the effect of vegetation characteristics on sedimentation in a flume environment. A diverse set of vegetation patches was seeded and manipulated for the experiments. The sedimentation on the plants versus “underneath the vegetation” was investigated and the effect of vegetation density, height, structural diversity, and leaf pubescence studied. The results confirmed their hypotheses and are discussed with other literature findings on the effect of in-stream vegetation on sedimentation processes.

The paper is well-written and structured. The methodology is clear, and the results are discussed in detail. It is an interesting contribution and I only have some minor comments regarding the flume experiments and test program as well as some suggestions regarding the figures. Based on my opinion, the paper only needs minor revision.

Comments per section:

Please check “affect” and “effect” in the text (L36; L72)

Abstract

1. Please add 1-2 sentences on how the sedimentation was determined (as described in Sample processing)

Introduction

2. L53-54: Add sediment and “nutrient transport”, as in L54 you refer to “overfertilization”

Experimental set-up

3. L175: Why is it important to state the company that built the flume?

4. L182: What do you mean by “roughen the flow” – that they acted as a flow straightener to suppress secondary currents and establish uniform flow conditions? Please revise.

5. L183 and in the text: Please refer to “upstream and downstream” and not “in front and behind”

6. L185: under dry conditions instead of at ?

7. It is not clear to me how the water and the sediment / clay was mixed and where. Was there a recirculating pump and the mixture of water and sediment was flowing through the test section with the respective discharge? Did the sediment settle upstream of the test section? Did you add the sediment prior to every run? It would be helpful to add some more information to the text and also a test program. It is not so clear to me how many runs were conducted.

8. Regarding the flow depth: Have you considered to perform flume experiments under non-submerged, so emergent conditions or vary the discharge? Did you choose the discharge and flow depth based on the flume capacity? Why were these parameters not varied / discussed?

Experiment conduction (I recommend Experimental procedure)

Results

9. L273: The variation of the flow velocity is similar to the mean value. Why? Was it due to the measurement device?

Discussion

10. Similar to comment 8, it would be interesting to discuss the tested flow conditions (discharge, flow depth / submergence level) and characteristics of sediment and clay particles in the flow – and how these parameters affect the sedimentation processes. The flow velocity and particle size will affect the sedimentation processes, so more information on how you chose them would be interesting – also with respect to how to upscale them to prototype conditions.

Figures

11. Fig. 3: What does a – b – b – b stand for above the box plot? It looks similar to the indication of the subfigures; please adapt

12. Fig. 5-6: I recommend starting with 0 at the x-axis

13. Fig. S1: I highly recommend including this figure in the main text, as it nicely illustrates what the experiments looked like

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment

PONE-D-20-34689R1

Dear Dr. Kretz,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Cristina Armas

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: