Assessing the Impacts of Tidal Creeks on the Spatial Patterns of Coastal Salt Marsh Vegetation and Its Aboveground Biomass

Round 1

Reviewer 1 Report

Specific comments:

lines 60-74, 129-131, 141-147 and many more: formatting issues

line 65: Explain why you named UAVs as active remote sensing technique

line 124: convert the hm2 unit of area to more illustrative (km2)

line 126: flight track lines / transects (?)

line 150: suggested reference:

• 10.1016/s0034-4257(01)00295-4

line 151: be careful with Kappa:

• 10.1080/01431161.2011.552923

lines 176-182: provide the utilised software

line 183: correct the sentence

line 218: you need to supplement which machine learning methods produced which results

line 347: I suggest adding other ecosystems, like glacial:

• 10.1109/tgrs.2021.3091771

Author Response

Thank you very much for your time and effort in reviewing our manuscript and providing valuable comments and suggestions. We have carefully read the comments, and tried best to make revisions. We hope the revision can be meet with approval. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments to the Author

Review of the manuscript “Assessing the impacts of tidal creeks on the spatial patterns of  coastal salt marsh vegetation and its above-ground biomass”

This study intends to identify spatial patterns of plant vegetation and its above ground biomass (AGB) in a coastal salt marsh. The manuscript used Digital Elevation Model and Digital Surcafe Model by LiDAR data acquired by an unmanned aerial vehicle. Optical images were obtained by a drone DJI Phantom 4 Pro. In addition, in-situ vegetation data (species composition and average value of AGB (kg m-2)) were obtained.

The manuscript is well written and organized and addresses a topic of great relevance through modern techniques for studying coastal environments. The data analysis methods are appropriate and support most of the conclusions. Therefore, I recommend publication after a moderate review. I made  suggestions and questions directly to the text of the work.

My main concern is the analysis (4. Discussion, 4.1. Impacts of tidal creeks on the spatial distribution of salt marsh communities and their AGB) and  conclusions about the relationship between channel distance and above-ground biomass. I recommend that authors analyze the relationship between terrain topography (DSM) and the canopy height model. I think it would be very useful to present an integrated figure with maps of the spatial distribution and area compositions of salt marsh communities, canopy height model, digital surface model (terrain topography) and the spatial distribution of above-ground biomass. The tidal range, morphology (terrain topography, drainage system, type of sediments), the type of depositional environment (margin of a lagoon, delta, estuary, river) significantly influence the porewater salinity and vegetation structure (taxa, density, canopy height), and therefore the spatial distribution of above-ground biomass. These relationships produce a positive feedback, as the biomass accumulated in the sediments increases the marsh productivity, increasing the vegetation density which in turn causes an increase in sediment retention, causing an elevation in the substrate topography (e.g. Cao et al., 2021). Therefore, coastal vegetation depends on the depositional environment, but once established, it modifies the drainage network, the sediment grain size, and the substrate topography, improving environmental conditions for a new generation of species that are more demanding regarding the conditions of salinity, topography, sediment grain size following a gradual succession in vegetation types. This work has the potential to discuss these issues and improve the discussion and conclusions about the spatial distribution of above-ground biomass.

Below are some minor suggestions that are also highlighted in the pdf file..

Introduction

I recommend adding a sentence to highlight the relevance of Unmanned Aerial Vehicles in coastal studies, such as “The use of unmanned aerial vehicles (UAVs) data in environmental sciences has increased during the last 10 years, including mangroves [1–3], coastal dunes [4,5], and seagrass beds [6]. (line 60).

Porewater salinity in tidal flats is related to the estuarine salinity gradient and topography of the environment. (line 54).

Study area

What is the tidal range of the study area?

2.2.2. LiDAR and optical image data acquisition

-check the paragraph between the lines 129 – 131.

4. Discussion

4.1. Impacts of tidal creeks on the spatial distribution of salt marsh communities and their AGB

The manuscript mentions variation of salinity, but does not present salinity data.

References:

1-Hsu, A.J.; Kumagai, J.; Favoretto, et al., Driven by Drones: Improving Mangrove Extent Maps..Remote Sens. 2020. https://0-doi-org.brum.beds.ac.uk/10.3390/rs12233986

2-Cohen, M.C.L.; de Souza, A.V.;et al..Effects of the 2017–2018 Winter Freeze on the Northern...Geomorphology 2021. https://0-doi-org.brum.beds.ac.uk/10.1016/j.geomorph.2021.107968.

3-Cohen, M.C.L.; de Souza, A.V.; et al. Effects of Beach Nourishment Project on Coastal...Remote Sens. 2021.https://0-doi-org.brum.beds.ac.uk/10.3390/rs13142688.

4-Laporte-Fauret, Q.; Marieu et al.  Low-Cost UAV for High-Resolution. J. Mar. Sci. Eng. 2019. https://0-doi-org.brum.beds.ac.uk/10.3390/jmse7030063.

5- Fabbri, S.;  Using High-Spatial Resolution...Remote Sens. 2021. https://0-doi-org.brum.beds.ac.uk/10.3390/rs13101987

6- Rende, S.F.; Ultra-High-Resolution Mapping. J. Mar. Sci. Eng. 2020.  https://0-doi-org.brum.beds.ac.uk/10.3390/jmse8090647.

7-Cao, H., Zhu, Zhenchang, Van Belzen, Jim, Gourgue, Olivier, Van De Koppel, Johan, Stijn Temmerman, O., Herman, Peter M J, Zhang, Liquan, Yuan, Lin, Bouma, Tjeerd J, Cao, C.:, Zhu, Z, Van Belzen, J, Gourgue, O, Van De Koppel, J, Temmerman, O.S., Herman, P M J, Zhang, L, Yuan, L, Bouma, T J, 2021. Salt marsh establishment in poorly consolidated muddy systems: effects of surface drainage, elevation, and plant age. Ecosphere 12, e03755. https://0-doi-org.brum.beds.ac.uk/10.1002/ECS2.3755

Comments for author File: Comments.pdf

Author Response

Thank you very much for your time and effort in reviewing our manuscript and providing valuable comments and suggestions. We have carefully read the comments, and tried best to make revisions. We hope the revision can be meet with approval. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Line 60: Remote-sensing should be abbreviated in the brackets and further in the text used as an abbreviation RS.

Lines 63-74. An overview and the most recent reference must be given to highlight current trends in remote sensing in coastal and marine nature areas.

Lines 76-88 should be moved to the Study Area description.

Lines 89-106. The Study Area description must be more explicit for an international audience, especially from other continents.

Lines 295-373. The Discussion must be rewritten and substantially abridged with fleshed-out main arguments: the main findings (in brief) and the most promising avenues for further research.

Lines 374-388: Conclusions must be rewritten. In the present form, they are superficial and unconvincing. The conclusions must provide a brief yet specific link with the quantitative findings of the research. For example, you write: “The RFR model was found to perform best in terms of prediction accuracy, yielding reliable AGB estimations for salt marshes.” Please, reiterate the proof since I didn‘t find any convincing validation for this statement in the Results section.

Author Response

Thank you very much for your time and effort in reviewing our manuscript and providing valuable comments and suggestions. We have carefully read the comments, and tried best to make revisions. We hope the revision can be meet with approval. Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

My comments were addressed properly. I would like to see this paper published 

Reviewer 2 Report

The authors adequately addressed the questions and recommend accepting the manuscript.

Reviewer 3 Report

Everything looks fine

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.