PWAT-D-21-00027

Influence of water storage and plant crop factor on green roof retention and plant drought stress

PLOS Water

Dear Dr. Soni,

Thank you for submitting your manuscript to PLOS Water. After careful consideration, we feel that it has merit but does not fully meet PLOS Water'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.

Please submit your revised manuscript by Nov 25 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 water@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pwat/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Muhammad Jehanzeb Masud Cheema

Academic Editor

PLOS Water

Journal Requirements:

1. Please provide more details on the Ficinia nodosa specimens used in your study. For example, please list of the source, genotype of the plant you used, and whether there are any voucher specimens available.

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Additional Editor Comments (if provided):

Dear Authors,

The reviewers have raised some specific questions regarding plant stresses/density and overall ET calculations. Additional information on plant stresses and clarification of Kc and overall ET are required. Especially discussion and conclusion section need improvements. Also improve Figures in the revised version.

You are invited to resubmit the manuscript after taking care of reviewers' comments.

Thanks

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Water’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. 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

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

PLOS Water 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

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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: The article is well laid out and addresses one of the critical components of green roof design: plant selection.

I have some minor comments below that will improve the clarity of the article

Introduction

Line 80-91. I found the paragraph on Plant crop factors (Kc) a bit confusing and repetitive. Additionally, as this article is being published in an open general journal the introduction should cater to audiences unfamiliar with Kc. I suggest improving clarity by defining Kc as a derivative of ET and ET0 at the beginning of the paragraph.

I think a bit of background should be given on plant drought stress considering you are evaluating rainfall retention and plant drought stress in your water balance model.

Methods

Line 136-138- for clarity might be better to state the type of watering system.

Line 139,140 – I am not quite sure what is the point you are trying to make here. Not sure how these plants are representative of an established green roof.

Results

The font on the graphs were a bit small on the PDF version of the manuscript.

Discussion

Line 329 -337 – I think you could mention here that the reduction in ET could and increase biomass could also be due to a reduction of stress due to the shading of neighboring plants.

Line 353-360- How would this have changed if plants were stressed. the temperatures of your glasshouse suggest the plants were under little to no heat stress. It is unfortunate that you could not compare above and below-ground biomass. It could have indicated if plants were stressed.

Line 397-407 - This paragraph contradicts earlier paragraphs that state that increasing planting densities and substrate depth only slightly increased ET.

Line 410- How would this change if using different species and substrates. Looking forward with increasing extreme temperature events, will your conclusions on 150 mm depth still be valid.

Conclusions-How do you expect conditions on a green roof ( increased heat, light and wind stress) affect your findings/ conclusions?. I think you should discuss this a bit more and list it as a limitation.

Reviewer #2: In the manuscript “Influence of water storage and plant crop factor on green roof retention and plant drought stress”, Soni et al. investigated the retention capacity and evapotranspiration rate of green roofs, characterized by different soil layer thickness and vegetation density. In particular, they estimated, through a glasshouse experiment under well water conditions, the variability of the plant crop factors (Kc) in correspondence to different plant density. Contrary to what expected, the increase of plant density led to small increase of the water retention and to a higher drought stress.

Although it presents interesting and innovative results, that will have high impact on the future design of green roofs and other green infrastructures, the manuscript needs some minor adjustments and modifications before publication in an international journal such as PLOSWater.

The discussion section, in particular, could be improved, rephrasing some ambiguous sentences and ensuring that the comparison with other case studies and results from the literature is fair, i.e., under similar climatic conditions or with the same vegetation type.

Moreover, it should be better specified where the hypothesis that doubling substrate depth (water storage) or plant density (Kc) will double overall ET comes from.

The manuscript is clear, well written and well structured.

Specific comments [Page, line]

[3, 54] Please support this sentence with some references:

Cristiano, E., Farris, S., Deidda, R. and Viola, F., 2021. Comparison of blue-green solutions for urban flood mitigation: A multi-city large-scale analysis. Plos one, 16(1), p.e0246429.

Karteris M., et al., Towards a green sustainable strategy for Mediterranean cities: Assessing the benefits of large-scale green roofs implementation in Thessaloniki, Northern Greece, using environmental modelling, GIS and very high spatial resolution remote sensing data. Renewable and Sustainable Energy Reviews, 2016. 58: p. 510–525.

Zhou D., et al., Assessing the hydrological behaviour of large-scale potential green roofs retrofitting scenarios in Beijing. Urban Forestry & Urban Greening, 2019. 40: p. 105–113.

[3, 62] Not only soil depth, but also soil type

[3, 70] Please consider adding some reference regarding the performance of succulent species

Cristiano, E., Urru, S., Farris, S., Ruggiu, D., Deidda, R. and Viola, F., 2020. Analysis of potential benefits on flood mitigation of a CAM green roof in Mediterranean urban areas. Building and Environment, 183, p.107179.

Li, W.C. and Yeung, K.K.A., 2014. A comprehensive study of green roof performance from environmental perspective. International Journal of Sustainable Built Environment, 3(1), pp.127-134.

Stojkov, I., Cipolla, S.S., Maglionico, M., Bonoli, A., Conte, A., Ferroni, L. and Speranza, M., 2017, September. Hydrological performance of Sedum species compared to perennial herbaceous species on a full-scale green roof in Italy. In International Symposium on Greener Cities for More Efficient Ecosystem Services in a Climate Changing World 1215 (pp. 117-120).

[Fig. 2] Please modify the legend, either including it in both plots or outside the plots, to highlight that it refers both to A and B. Also specify the units in the legend, or better refer to extensive and intensive green roof. Same comments for Fig. 3,4,5,6

[Fig. 2] Specify better in the caption what the letters above the boxplot mean.

[17, 314] Please consider shortening the paragraph title

[17, 316] What was this hypothesis based on? any reference?

[18, 318-326] This paragraph is a bit ambiguous. You stated that the observed ET is higher than in other studies, but you are comparing it with different vegetation, and only at the end you compare it with the same vegetation type. Please rephrase these lines.

[19, 362] I wouldn’t say that the results contradict the results found in the literature, values are just a bit lower and the different experiment conditions could be the causes of these differences, as mentioned in the following lines.

[20, 376-377] Do the other studies investigate similar climatic conditions? If not this needs to be specified, it does not make sense comparing the retention capacity if the climatic conditions are different.

[23, 439] Remind in the conclusions that the water deficit phase has been only simulated, and it will be interesting to repeat the experiment under this condition.

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Reviewer #1: No

Reviewer #2: No

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Influence of water storage and plant crop factor on green roof retention and plant drought stress

PWAT-D-21-00027R1

Dear Dr. Soni,

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. The journal will begin publishing content in early 2022.

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Kind regards,

Emily Chenette

Staff Editor

PLOS Water

Additional Editor Comments (optional):

Reviewers' comments: