Supporting SDG 15, Life on Land: Identifying the Main Drivers of Land Degradation in Honghe Prefecture, China, between 2005 and 2015

Round 1

Reviewer 1 Report

All the comments are in the attached files. 

Generally spoken resolution of all figs should be improved - details in the attachment.

Comments for author File: Comments.pdf

Author Response

Dear Sir/Madam,

Thanks very much for taking the time to review this manuscript. I really appreciate all your comments and suggestions!
Please find the response to the comments attached.

Best regards,
Tuo

Author Response File: Author Response.docx

Reviewer 2 Report

Since more than 20 years international groups are dealing with scientific investigations about land degradation in China. One of the first groups have been researchers of the University of Stuttgart, headed by Prof. Peter Treuner, in collaboration with the Chinese Ácademy of Sciences, Beijing/Branch Nanjing, and the project was called "Sustainable Integrated Land Use Planning", in which a new method of indicators have been proven. Maybe you will find some references for SILUP, because the Chjinaes Academy of Science was really pleased about the outcome of this very ambitions investigation.

Author Response

Dear Sir/Madam,

Thanks for your suggestions.

I read some papers related to SILUP. I think the project is very important. So, I add a description of SILUP in the Introduction section (Row 66-70).

Best regards,

Tuo

Reviewer 3 Report

Dear colleagues, 

thank you for adopting the existing methodology of SDG15 indicator evaluation by Earth Observation, especially the indicator 15.3.1, to the test region Honghe. Of course, it is helpful to see that the SDG rules in place are working and are appropriate. Therefore your observations are valuable. 

The topic is clearly written and the evaluation of the indicator in the test region is well described.
I am missing novelty in this contribution. What are the new aspects, that make this paper worth reading? Is is the local impact of indicator 15.3.1? Is it a new method of measurement? Is it an extended indicator definition? Is anything of the SDG rules in place not appropriate? What is the scientific originality in your contribution?

Based on these very basic questions, allow me to add my observations, which should be adressed: 

1. on the basis of the test region Honghe a well established procedure of SDG is used to evaluate the region against indicator 15.3.1. What are the main findings that support the indicator - or create requirements to adopt it?
2. You describe that Google Earth has been used for your evaluation. Do you think that Google Earth is an appropriate toolset to analyse and evaluate a spatial indicator and to make area by area estimations? I recommend to make use of a professional GIS system (e.g. QGIS, if a open source solution is helpful). 
3. You make use of NDVI for some of your evaluation. Is this enough? Don´t you need any extension? Any more precise vegetation index that may deliver better results? A comparison of appropriate vegetation indeces is missing. You should spend some words on the character of NDVI and similar EO methods. 
4. You indicate that government policy can play an important role. Please describe "how", what are proposed actions or governance models that could be installed. There is no description of existing governmental actions in this region. 
5. In the end, in your conclusions, you indicate that resolution is an important factor and that 250m resolution has been used for the observation. 
   First of all, the specification of your test case should be at the beginning, when you describe your testsetting. 
   Second a discussion on the impact of resolution is missing. How does a change of resolution change your results? You should add a section on this consideration. 

By considering my statements and hints, this could be an important scientific contribution, which could help an acting SDG community and government. 

Best regards

 

Author Response

Dear Sir/Madam,

I am very grateful for your comments about the manuscript. According to your advice, we amended the relevant part of the manuscript. Some of your questions were answered below.

 

Point 1: What are the new aspects, that make this paper worth reading? Is it the local impact of indicator 15.3.1? Is it a new method of measurement? Is it an extended indicator definition? Is anything of the SDG rules in place not appropriate? What is the scientific originality in your contribution?

Response 1:

The goal of SDG 15.3.1 is to achieve a land degradation-neutral world. This is a worldwide problem. Developed countries have done better in this field. However, it is more difficult for developing countries to achieve land degradation neutrality. China is a developing country. In China, more studies are concentrated in areas with better development, especially the southeast coastal areas such as Zhejiang and Jiangsu, because it is easier to get local funding for research. The value of this article is to assess land degradation in less developed areas, where funding is limited. We should pay more attention to these areas.

A national report on land degradation is essential. The generalized report ignores local features. Simple averaging of national degradation proportions at regional (province, city, and prefecture) scales may indicate the relative overall degradation levels regionally. This paper gives more details on the prefecture scale in the Framework for Land Degradation Neutrality (LDN).

 

Point 2: On the basis of the test region Honghe a well-established procedure of SDG is used to evaluate the region against indicator 15.3.1. What are the main findings that support the indicator - or create requirements to adopt it?

Response 2: SDG 15.3.1 takes the proportion of land that is degraded over the total land area as an indicator.  This paper tries to find why this happens in Honghe, identify the main drivers of land degradation in Honghe Prefecture, which allows designing solutions to prevent further degradation.

 

Point 3: You describe that Google Earth has been used for your evaluation. Do you think that Google Earth is an appropriate toolset to analyze and evaluate a spatial indicator and to make area by area estimations? I recommend making use of a professional GIS system (e.g. QGIS, if an open source solution is helpful).

Response 3: I agree with the suggestion of using open-source software. Trends.Earth used for area estimation in this article is an open-source QGIS plugin. The high spatial resolution images of Google Earth are an alternative to insufficient project funding. It is used to validate the change for sub-indicators. If the funds are sufficient, images from Quick Bird and GeoEye are better.

 

Point 4: You make use of NDVI for some of your evaluation. Is this enough? Don´t you need any extension? Any more precise vegetation index that may deliver better results? A comparison of appropriate vegetation indices is missing. You should spend some words on the character of NDVI and similar EO methods.

Response 4: As suggested, we made a comparison between NDVI and EVI and explained why we chose NDVI. (Row 132-141)

 

Point 5: You indicate that government policy can play an important role. Please describe "how", what are proposed actions or governance models that could be installed. There is no description of existing governmental actions in this region.

Response 5: We added new content to describe what they should do in this region. (Row 306-314)

 

Point 6: In the end, in your conclusions, you indicate that resolution is an important factor and that250m resolution has been used for the observation. First of all, the specification of your test case should be at the beginning, when you describe your test setting. Second a discussion on the impact of resolution is missing. How does a change of resolution change your results? You should add a section on this consideration.

Response 6: We added a paragraph to discuss the impact of resolution and gave the reason why 250 m resolution was used. (Row 94-100)

 

Once again, thank you very much for your comments and suggestions.

 

Best regards,

Tuo

Reviewer 4 Report

This study aims to identify the main drivers of land degradation in the Honghe Prefecture, Southwest Plateau of China in the time period of 2005-2015. I recognize the efforts made by the authors for preparing the manuscript, but the potential of contribution for international readers is limited in terms of results obtained which is specific for a prefecture in China. Some criteria used to define different levels of degradation are based on global thresholds suggested by the Trends.Earth plataform which should be tested or validated for local conditions of the prefecture. Same for the case of estimating soil organic carbon. Others seem to be based on local experience of authors (for example, performance, one of the subindicators of land productivity). It is OK to go empirical but some explanation needs to be provided to readers so that they can apply to other study areas. Other comments are:

1. Title: Please, identify the meaning of SDG15 in the title.
2. MOD13Q1: the existence of EVI should be reported by the authors.
3. Table 1. I don´t understand why one type of conversion (e.g., croplands to wetlands) is negative and the opposite way (wetlands to croplands) is not positive. In this specific example, I don´t think wetland is an appropriated term since wetlands have their own ecological functioning. Perhaps a more appropriated term would be inundated area.
4. Land productivity. Please specify what is MK test.
5. The use of NOAA VIIRS night light data and the high resolution images available in the Google Earth platform should be stated in the Materials and Methods section.
6. References. References are not in the style adopted by the journal. For example, all authors should be listed (except if there are more than 10 authors, please, check the instructions); journal´s name should be in abbreviated form; digital object identifier should be provided.

Author Response

Dear Sir/Madam,

Thanks very much for your valuable suggestions.

In the following pages are our point-by-point responses to each of the comments of you.

 

Point 1: Some criteria used to define different levels of degradation are based on global thresholds suggested by the Trends.Earth platform which should be tested or validated for local conditions of the prefecture. Same for the case of estimating soil organic carbon. Others seem to be based on local experience of authors (for example, performance, one of the sub indicators of land productivity). It is OK to go empirical, but some explanation needs to be provided to readers so that they can apply to other study areas.

Response 1: We added a paragraph, which included the reason why we chose the default thresholds and method. As suggested, we provided some advice on how to improve the consistency and accuracy of assessing land degradation in other areas. (Row 403-410)

 

Point 2: Title: Please, identify the meaning of SDG15 in the title.

Response 2: “Life on Land” was added after “SDG 15” in the title.

 

Point 3: MOD13Q1: the existence of EVI should be reported by the authors.

Response 3: We rewrote the sentence by adding EVI. (Row 109)

 

Point 4: Table 1. I don´t understand why one type of conversion (e.g., croplands to wetlands) is negative and the opposite way (wetlands to croplands) is not positive. In this specific example, I don´t think wetland is an appropriated term since wetlands have their own ecological functioning. Perhaps a more appropriated term would be inundated area.

Response 4: Thanks for the suggestion. Major change process notes were added for wetlands. (Row 125-126)

 

Point 5: Land productivity. Please specify what is MK test.

Response 5:  we revised the sentence and added two references. (Row 146)

 

Point 6: The use of NOAA VIIRS night light data and the high-resolution images available in the Google Earth platform should be stated in the Materials and Methods section.

Response 6: we added them in section 2.2Data sources. (Row 103)

 

Point 7: References. References are not in the style adopted by the journal. For example, all authors should be listed (except if there are more than 10 authors, please, check the instructions); journal´s name should be in abbreviated form; digital object identifier should be provided.

Response 7: we downloaded the MDPI style from https://endnote.com/style_download/mdpi/ and updated the references with DOI.

 

Special thanks to you for your comments.

 

Best regards,

Tuo

Round 2

Reviewer 3 Report

Thank you for following the comments and adding some important parts. 

Author Response

Dear Sir/Madam,

Thank you so much! We appreciate your recognition.

For language issues, we corrected errors and improved the language of this manuscript via MDPI English Editing Service.

We also revised the Discussion and Conclusions based on guest editors' comments.

King regards,
Tuo

Author Response File: Author Response.pdf

Reviewer 4 Report

All my concerns in the previous version were addressed properly. Paper is ready to be published.

 

Author Response

Dear Sir/Madam,

Thank you so much! I appreciate your recognition.

For language issues, we correct errors and improve the language of this manuscript via the MDPI English Editing Service.

King regards,
Tuo

Author Response File: Author Response.pdf