Evaluating the Losses and Recovery of GPP in the Subtropical Mangrove Forest Directly Attacked by Tropical Cyclone: Case Study in Hainan Island

Round 1

Reviewer 1 Report

The manuscript is very interesting, I decided to give the manuscript a minor revision. After supplementing the relevant instructions and modifying the pictures, it could be accepted. Mangrove forests are important ecosystems for carbon sequestration and coastal protection. Estimating their productivity and understanding their response to extreme weather events can help us better manage and protect them. The LUE model is a widely used method for estimating GPP of vegetation based on remote sensing data for terrestrial ecosystem. Using in the mangrove ecosystem is indeed an innovation and an icebreaker. The authors did a great job, not only talking about the recovery and impacts, but also that the factors such as phenological rhythm and forest age increase are difficult to avoid when we often use time-series images have been eliminated. The author's thinking on the subsequent impact of extreme events is clear and worthy of promotion. Here's what needs to be discussed further:

 

1.     Let us focus on two figures in the manuscript. The figures will give readers the first impressions of the manuscript. The maps in the manuscript are very textured, but what the author intends to express with Fig. 6 is affected by the quality of the figure. The author needs to redraw Figure 6 and keep the level of the whole figures consistent. Too much white space, size too small.

 

2.     According to the author's cyclone screening protocol, it is impossible to screen out tropical depressions and tropical storms, so it is suggested that the authors had better to briefly remind the target events in the Introduction section. Otherwise, readers may read through the manuscript looking for the effects of various cyclones.

 

3.     I agree with authors that there is almost no LUE model for estimating mangrove ecosystem photosynthesis. But if the authors chose LUE model to estimate mangrove GPP, they should tell readers the accuracy, at least compared to the results of widely used products such as MODIS. Only in this way can readers accurately judge the size of uncertainty.

 

4.     Only one tropical cyclone event, Sarika, was filtered out by the author's rules. The result is great. I'm just curious, if the tropical cyclone events around 1950 or around 1990 were selected out, how do the author design the research plan?

 

5.     Figure 2 should be the same size as Figure 5, the font, the frame and even the color.

 

6.     The contents in 4.3 Uncertainty analysis (DBH, Height, Directions) should be listed in the Section 4.4 the impact from Tree Species and Physical Properties, or some other title.

 

7.     Finally the mangrove ecosystem recovery to the Pre-Level, and the authors said the duration is about two years (2016 and 2017), so by the end of 2017, should the restoration be completed?. And why the mean GPP in 2017 is significantly lower than GPPbaseline?

 

 

8.     How to understand the GPP in 2018 is higher than that in 2015? Is it the carry-out or resilience effect after the disturbance?

Comments for author File: Comments.pdf

Author Response

Dear Sir,

We appreciate the detailed and useful comments and suggestions from you. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied comments carefully and have made corrections which we hope meet with approval.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript submitted by Wu et al. primarily conducts an analysis of the response of the Hainan Island mangrove ecosystem's GPP to tropical cyclones, including disturbances and recovery. Overall, this is an interesting topic and the manuscript is well-written. However, I suggest a major revision, mainly due to the excessive length of the data and methodology sections. 

General comments: 

(1) The data description section must be shortened, and it is strongly recommended that the authors provide a table to summarize the data used in the study, including spatial resolution, time coverage, data source, etc.

(2) Is there any innovation in section 2.3.1? If not, please simplify it as much as possible. Additionally, it is suggested that the authors provide a flowchart to clearly depict the work of this manuscript. 

Specific comments: 

L.50: Please revise “upplight” to “uplift”. 

L.58: This sentence needs to be carefully reviewed. 

L.129: Please revise “research area” to “study area”. 

L.152: Please give the full name of ROI. 

L.160: What is ANN? 

L.161: “A” should use lowercase.

L.186: Please revise the air maximum temperature to maximum air temperature and also check the whole manuscript on this. 

L.192: Please delete “the period”. 

L.201: Please use the full name the first time it appears, rather than here. It is also necessary to check the whole manuscript for this issue. 

L.252: Is there any innovation in this Section? 

L.301: Typos. 

L.557: The readability of Figure 6 needs to be improved.

Author Response

Dear Sir,

We are very grateful to your comments on the manuscript. We have modified the low-level mistakes and provided a flowchart in order to let readers understand the information we would like to convey. According to your comments, the material and method section have been improved by us in the revised manuscript. Once again, thank you very much for your comments and suggestions. They are very helpful to us.

The specific comments you raised are addressed one-by-one in the word file. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Thanks for your contribution. In this article, the authors are mainly focused on assessing the impact of Typhoon Sarika on GPP’s dynamic change of mangrove forest in Danzhou Bay, Hainan. In my opinion, this is an interesting and timely manuscript. However, the English of the manuscript must be improved, it is difficult for me to understand what the authors want to express. Except English writing, some of the results are described unconvincingly to me. Here are my comments: (1) How could the authors prove that the obtained GPP results based on MVP-LUE are relatively accurate? Is there any relevant data that can be used for verification? Please comment on this. (2) The authors are suggested to add a technical flowchart in Section 2.3 so that readers can quickly understand the experimental process. (3) The authors are suggested to represent the geographic location of the field surveys in Figure l. (4) Line 419-421: As the authors mentioned, “We used the buffer analysis to establish the correlation relationship between the distance to coastline and the distance to typhoon eye and GPP loss (Figure.4 subplot) ”, a detailed explanation of how to achieve the established relationships should be provided as those shown in Figure 4, in order to prove the authors' conclusion about “The loss of mangrove GPP decreased with the increase in the distance to the track of SuperTY Sarika”. (5) In Section 3.4: In this section, the authors conclude that CW and fCover could fully recover to the level of Pre-TC, while LAI and CAB still not fully recover to the level of Pre-TC. However, the same conclusion cannot be drawn from Figure 5 to me, it looks like all of the four parameters were recovered to the level of Pre-TC, could the authors provide comments on this? Moreover, the authors are suggested to add results before the year of 2015, in order to prove that the four parameters remained stable before the TC occurred. (6) Line 568-570: As the authors mentioned, “According to our survey, the GPP loss of the mangrove ecosystem in Danzhou Bay was also significantly correlated with DBH (Figure.6 (b)); the larger the diameter at breast height, the more resistant it is to damage caused by typhoons”. However, it looks to me that the relationship between GPP loss and DBH is relatively complex, by using linear fitting is not appropriate here, hence the conclusion that GPP loss and DBH are significantly correlated cannot be approved. Please comment on this.

Author Response

Dear Sir,

Thank you very much for taking time to carefully review our manuscript. We are very grateful for your comments on the manuscript. Your comments have been of great assistance to us for improving and revising our manuscript as well as providing important guidance for our research. In particular, the suggestions you gave us on the aspect of result inference have greatly improved the scientific basis and rigor of the manuscript. We have substantially revised the original manuscript after considering these comments, and the changes are marked in green.

For the English expression (e.g., grammar and language) issue, we have made targeted improvements, and the revised manuscript has been edited by MDPI Language Editing Services. We have responded one-by-one to the detailed comments you raised.

Once again, thank you very much for your comments and suggestions. They have been very useful for us. We hope that the revised manuscript will meet with your approval.

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Thanks to the authors for their efforts. They have addressed all my comments and I recommend accepting this version of the manuscript.

Author Response

Dear Sir,
Thank you very much for taking time to carefully review our revised manuscript. We are very grateful for your comments on the manuscript. And it is also an honor for us that you recommend accepting the revised manuscript.

Reviewer 3 Report

No comments.

Author Response

Dear Sir,
I cannot thank you enough for taking time to carefully review the revised manuscript. We very appreciate the suggestion that you gave us for the original manuscript. And we also feel great honor that you would like to sign the review report of our revised manuscript.