Rapid Assessment of Ecological Integrity for LTER Wetland Sites by Using UAV Multispectral Mapping
Round 1
Reviewer 1 Report
Thank you very much for your valuable manuscript. I very appreciated that the study was undertaken at multiple spatial scales and using multiple tools, including field data as a reference. In my opinion, it is important to use field data, have a good knowledge of the area of interest which allow to control the quality of information obtained by remote sensing techniques.
In this study, authors investigated a UAV based and a satellite image based methods for obtaining indicators to assess the ecological integrity of Long-Term Ecological and Socio-Ecological Research Sites. Tested indicators were for example the followings: turbidity, aquatic plant species cover or inundation level. Authors applied their multispectral mapping approach on two study sites. On one of the study sites, they also examined the feasibility to upscale the information obtained at fine- and at medium scale to broad scale. They took the inundation level as an example for an ecological integrity indicator and suggested that the relationship between the multispectral information of UAV and satellite images.
The abstract gives a good global overview of the paper including the objectives. There is only the sentence in line 27 which is not clear. I also enjoyed the introduction giving a good description of the aim of the paper and the LTER and LTSER. From my point of view, it would be good to add a bit of background what has been already done in the topic (e.g. similar method but other environment etc).
The methodology is principally well constructed; however, I have few concerns and suggestions. In a general way, please try to be a bit more precise what exactly did you do. I found especially not clear enough the variables / indexes you exactly tested (ex. Line 209). It would be a possibility to complete Table 1 allowing to see the indexes you tested related to RS indicators and the EI indicators. I would also suggest to add a figure summarising the general workflow. You used different data sources, combined them, tested different indexes for different indicators etc. Therefore, a global workflow would be very helpful for reader. You could also make references in the text to the different parts of this global figure to help the reader see visually where we are and what you have done. Maybe the same figure (or any other solution) could help you to clarify which indexes / indicators actually (not) worked or worked with restrictions etc. Part 3.4 needs a great improvement concerning its organisation and its clarity (what did you do and why). I indicated more details about it in my specific comments (see pdf). It might be personal, but I think the figures could be improved to obtain a better visual but especially need to have some more details on it, such as legend. A figure should be understandable nearly alone. I could not identify on Figure 1 the study area corresponding to the UAV flight and the area covered by satellite images used for the upscale method (Figure 7c). In the result section, also please try to achieve a bit more clarity.
I would suggest two principle improvements to undertake in the discussion. The first is to link your results more to international literature (similar to introduction). Any other studies dealing with the same problems you were facing? Or, contrary, they applied maybe a similar approach on a same or a different environment with success? This could allow to give ideas how to improve your technique etc. The second one is the clarity of your results. What methods, indexes etc could be used in other studies and what not. If with some restrictions, what do you suggest for future users? If I want to use your method, what do I have to be careful about or do differently etc; some kind of guidelines which could also help you to point out your perspectives.
Please see the pdf version of the manuscript with specific comments and highlights in the text.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
First of all let us thank you for your helpful review. We are sure that the manuscript is going to greatly improve by incorporating your comments and suggestions. The study is the result of a close collaboration under the umbrella of LTER missions, therefore we are pleased that you find it of interest.
This document is intended to reply and address point by point your comments and suggestions in order to make clear our major consideration. With this purpose we, henceforth, will use blue italic font for your comments and regular black for our answers. We maintain your yellow highlights through the text. We have carefully read them and incorporated through the text and figures. Specific author comments indicate the changes introduced throughout the manuscript. Reviewer comments in the PDF have been also addressed. A specific section in this document is devoted to explain the changes introduced to improve the manuscript readability and understanding.
We sincerely hope it will increase manuscript understanding for the readers. We also provide the new reviewed version with the track changes
Sincerely, the authors
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript describe an application of image analysis approach for wetland monitoring. The results shows that UAV is a useful tool and has the potential to upscale to satellite image.
The topic is particularly interesting and the manuscript is well written and easy to read. On the other hand, I feel some parts, especially methods section, should be improved because there are some unclear parts. The details are as below.
1. Figure 1a: Please re-create Figure 1a because I don't understand where LTER is. I assume that the blue areas may be LTER. However, there are no legend and the number of blue area is less than 16 (I found only 15 blue area). So. please create more clear figure 1a.
2. RMSE of geometric charasteristics (L192-194, L254-257) How many validation points were used to calculate RMSE?
3. Reflectance comparison (L306-313): How did you compare S2 and Sequoia, while the resolutions of them were different? Do you calculate mean values of orhthomosaics derived from UAV?
4. Upscaling method (L245-251, L320-328) : I feel that L320-328 is conflation of method and results. For example, "Sequoia multispectral (L320) ... i.e. band 7 (L326) is not result but apparently method. Thus, the parts should be written in method section. Please clarify what you have done and your results. Then please write what you have done in method section and write the results in result section.
5 Upscaling method (L245-251, L320-328) : How did you select the specs of segment Mean shift which were15.5, 15, and 20?
6 L384-385: The sentence about "recovery process" seems a fair statement. However, I think the authors need to tone this down a bit. This is because you didn't measure "recovery" at all.
7 Figure 7a: Please add a scale.
8 Figures: I don't know well about the attribution of images but I think that you need citation or permission to use images that someone have rights. For example, I think you must provide attributions of S2 and eBee in Figure 7. Especially, the image of "eBee" is a copy and paste from a website (https://dronelife.com/2016/11/02/senseflys-ebee-plus/)! Similarly, Figure 2 is created from Google Earth. There is a guideline to use google earth in texts and please follow the guideline, especially about the citation of data provider. (https://www.google.com/permissions/geoguidelines/attr-guide/).
Author Response
Dear reviewer,
First of all let us thank you for your helpful review. We are sure that the manuscript is going to greatly improve by incorporating your comments and suggestions. The study is the result of a close collaboration under the umbrella of LTER missions, therefore we are pleased that you find it of interest.
This document is intended to reply and address point by point your comments and suggestions in order to make clear our major consideration. With this purpose we, henceforth, will use blue italic font for your comments and regular black for our answers. We have carefully read them and incorporated through the text and figures.
We sincerely hope it will increase manuscript understanding for the readers. We also provide the new reviewed version with the track changes
Sincerely, the authors
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Reply to review report by Reviewer 2
The manuscript describes an application of image analysis approach for wetland monitoring. The results show that UAV is a useful tool and has the potential to upscale to satellite image.
The topic is particularly interesting and the manuscript is well written and easy to read. On the other hand, I feel some parts, especially methods section, should be improved because there are some unclear parts. The details are as below.
We really appreciate your global assessment and therefore we have carefully addressed your comments and suggestions in order to improve our manuscript.
1. Figure 1a: Please re-create Figure 1a because I don't understand where LTER is. I assume that the blue areas may be LTER. However, there are no legend and the number of blue area is less than 16 (I found only 15 blue area). So. please create more clear figure 1a.
We have fully changed figure 1 following your suggestions and now it is much clearer with a comprehensive legend.
2. RMSE of geometric charasteristics (L192-194, L254-257) How many validation points were used to calculate RMSE?
Really thanks for the appraisal. We have added a sentence as follows “Absolute Root Mean Square Error (RMSE) was calculated using 7 recognizable points in both layers.”
3. Reflectance comparison (L306-313): How did you compare S2 and Sequoia, while the resolutions of them were different? Do you calculate mean values of orhthomosaics derived from UAV?
Yes, that was the way we did it. We have added a short sentence in the text.
4. Upscaling method (L245-251, L320-328) : I feel that L320-328 is conflation of method and results. For example, "Sequoia multispectral (L320) ... i.e. band 7 (L326) is not result but apparently method. Thus, the parts should be written in method section. Please clarify what you have done and your results. Then please write what you have done in method section and write the results in result section.
Indeed you are right. The other reviewer noticed it and we have moved the paragraph to methods section. Now the reading is much clearer.
5 Upscaling method (L245-251, L320-328) : How did you select the specs of segment Mean shift which were15.5, 15, and 20?
Actually these specs are the default and recommended ones by the software when dealing with multispectral images.
6 L384-385: The sentence about "recovery process" seems a fair statement. However, I think the authors need to tone this down a bit. This is because you didn't measure "recovery" at all.
Yes, we did not show in the study any result from time series of UAV images but we have started these periodical flights for long-term monitoring and we wanted to point out the relevance of such an approach by citing other exemplary studies.
7 Figure 7a: Please add a scale.
Done!
8 Figures: I don't know well about the attribution of images but I think that you need citation or permission to use images that someone have rights. For example, I think you must provide attributions of S2 and eBee in Figure 7. Especially, the image of "eBee" is a copy and paste from a website (https://dronelife.com/2016/11/02/senseflys-ebee-plus/)! Similarly, Figure 2 is created from Google Earth. There is a guideline to use google earth in texts and please follow the guideline, especially about the citation of data provider. (https://www.google.com/permissions/geoguidelines/attr-guide/).
Thanks for this appraisal. We have included proper citation in the captions of both figures.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The manuscript improved drastically. I have only a suggestion on the attribution of images. I understand that you have included citations of "eBee" and "Google Earth". However, I feel that you may need to include citation of "S2" in Figure 8. Please check the guideline.Author Response
Dear reviewer,
Thanks for your kind comment. We have added the following sentence to figure 8: “Sentinel-2 image downloaded from Wikimedia Commons.”
Sincerely,
The authors
