Spatiotemporal Analysis of Vegetation Cover in Relation to Its Driving Forces in Qinghai–Tibet Plateau

Round 1

Reviewer 1 Report

Forests 2023, 14, x entitled “Analysis of Spatial and Temporal Changes in Vegetation Cover and Driving Forces on the Qinghai-Tibet Plateau” by Xu and Wu.

 

General comments:

NDVI is considered one of the most important and widely used parameters for vegetation studies all over the globe. The NDVI can be utilised to detect changes in forest structure, such as alterations in tree density, and to identify forest regeneration areas. It can also be used to monitor the effects of forestry management practices (i.e., clear-cutting, thinning, and prescribed burning) on the overall growth of forest ecosystems. The index is highly effective in studying the spatiotemporal changes in forest dynamics in remote areas which are otherwise difficult to access. This MS entitled “Analysis of Spatial and Temporal Changes in Vegetation Cover and Driving Forces on the Qinghai-Tibet Plateau” intuitively tries to study the interrelationships between NDVI and various natural and anthropogenic factors. Although the paper claims that there is not much of an effect of anthropogenic factors on the vegetation trends of the Qinghai-Tibet plateau, but I suggest a few more anthropogenic factors (e.g., forest fires, land use and landcover changes, forest resource exploitation, forest degradation) in addition to the factors analysed here.

Overall, the manuscript is well written, and however, I made some comments to improve the quality of the MS.  

 

Specific comments:

Title: Can better be written as “Spatio-temporal Analysis of Vegetation Cover in relation to its Driving Forces in Qinghai-Tibet Plateau”

 

Abstract:

Lines 8-12, Can better be written as “Tibet Plateau of Qinghai supports complex vegetation types which are ecologically fragile and sensitive to climatic factors. Therefore, it is important to understand the changes in vegetation and the factors responsible for these changes and to maintain the ecosystem balance and promote sustainable development in the region”. Please write a concluding sentence in the last of abstract.

 

Introduction:

Anthropogenic factors have frequently been reported to alter forest structure and functioning in different parts of the world as they are directly affecting the vegetation composition and regeneration, however, in this study the authors have shown the role of climatic factors like precipitation over the anthropogenic factors. Therefore, I think if the authors focus on this peculiar aspect of their study in introduction, it will improve the outcome of the study.  Further, there are minor comments may be taken care of as listed below:  

 

Comment 1: Line 36: Use “Normalised Difference Vegetation Index” instead of “normalised difference vegetation index” with abbreviation (NDVI) when used for the first time followed by abbreviations throughout the MS.

 

Comment 3: Line 51: Use “of” instead of “on”.

 

Comment 4: Line 76: Kindly write “Sen’s slope method” instead of “Sen slope method” throughout the M.S.

 

 

 

Data Sources and Research Methods:

The versions of ArcGIS and MATLAB used for the study should be mentioned in the respective places, like Line 130: mention the software versions of ArcGIS used in the study.

Line 134: mention the software version of MATLAB used in the study.

 

Research Methodology:

Since the M.S. uses the popular Mann-Kendall and Sen’s slope nonparametric tests, incorporating the original works of these authors mentioned below in the reference section is suggested.

1. Mann, H.B., 1945. Nonparametric tests against trend. Econometrica 13, 245–259.

2. Kendall, M.G., Stuart, A., 1968. The Advanced Theory of Statistics: Design and Analysis, and Time-series, vol. 3. Charles Griffin & Company Limited, London.

3. Sen, P.K., 1968. Estimates of the regression coefficient based on Kendall’s tau. Journal of the American Statistical Association 63, 1379–1389.

 

Results and Analysis:

The results have been explained briefly. However, minor suggestions are mentioned below:

Line 268: Kindly remove the (-) sign before 0.206-a^-1 as it already mentions a decreased rate. It can be written as: “the proportion area of this cover class decreased at a rate of 0.206-a^-1.”

Similarly Line 271, remove the (-) sign before 0.068-a^-1, and line 273: remove the (-) sign before 0.384-a^-1.

 

Line 312: Grammatical error: Please use “exceeds” instead of “exceeding”.

 

Line 388: Please check the value 0.11. It should be 0.011, as per Figure 9 (a).

 

Line 400: The words “we can see that” are repeated and can be deleted.

 

Conclusion and Discussion:

 

Change this section to Discussion followed by Conclusion in the last

 

Conclusion should be briefly described.

 

Line 443: Please use “during the study period” instead of “in the study period”.

Line 465: Please use “of the interactions” instead of “for the interactions”.

 

 

 

 

 

see comments above

Author Response

对于研究文章：

尊敬的审稿人：

问候！

非常感谢您对稿件的认真和专业审查，您的评论对本文和我个人都非常重要。我将在以下段落中回答您的评论：

1. 关于您在“一般性意见”部分提出的更多人为因素（例如森林火灾、土地利用和土地覆盖变化、森林资源开发、森林退化）的建议，我认为这是非常合理的，我已将这个想法添加到第 4.1 节文章的讨论部分，作为下一步研究的重点。下一项研究的重点。
2. Regarding your suggestions for the "Specific comments" section: (1) I think your revision of the title is more concise and professional, so I have directly adopted your suggested wording. (2) I have also directly adopted your suggested words in the abstract section. (3) I have also adopted all of your suggestions for grammatical errors and text in the Introduction section, especially the fourth suggestion which I directly used the full name (Theil-Sen slope method), which is slightly different from your suggestion. (4) In the data sources and research methods section, I added the specific version of the software. References to the original authors' literature were added to the Research Methods section. (5) In the Results and Analysis section, I removed the "-" sign before the numbers in the original text. All other grammatical errors were modified. (6) In the Conclusion and Discussion section, the order of conclusion and discussion was replaced. Grammatical errors in the conclusion section were also corrected.

      If there are still flaws in the results of the revision, I hope you will continue to give us your advice, thank you again for your review, and I wish you a happy life.

Reviewer 2 Report

Dear Authors,

The submitted manuscript titled „Analysis of spatial and temporal changes in vegetation cover and driving forces on the Qinghai-Tibet Plateau” contains valuable results, which might interst an international audience. In my opinion the manuscript is generally well-written, however I have found some imperfections, which should be corrected or at least clarified. I listed them below:

1.       The Figures 3,4,6,7,8 and are illegible. They should be enlarged.

2.       The chapter Discussion should be placed before secton Conclusions.

3.       In my opinio very valuable would be compare Your results with publications reffering to spatio-temporal changes of vegetation cover also in  other regions.

4.       Plesae, look into following literature sources. Perhaps, some of them will be helpful in manuscript corrections:

·         Tian, Y., Bai, X., Wang, S. et al. 2017. Spatial-temporal changes of vegetation cover in Guizhou Province, Southern China. Chin. Geogr. Sci. 27, 25–38. https://doi.org/10.1007/s11769-017-0844-3

·         Peng Li, Jing Wang, Mengmeng Liu, Zenghui Xue, Ali Bagherzadeh, Mengyun Liu 2021. Spatio-temporal variation characteristics of NDVI and its response to climate on the Loess Plateau from 1985 to 2015,CATENA, 203,105331, https://doi.org/10.1016/j.catena.2021.105331.

·         Weiguo Jiang, Lihua Yuan, Wenjie Wang, Ran Cao, Yunfei Zhang, Wenming Shen, 2015. Spatio-temporal analysis of vegetation variation in the Yellow River Basin. Ecological Indicators,51,117-126. https://doi.org/10.1016/j.ecolind.2014.07.031.

·         Tulokhonov, A.K., Tsydypov, B.Z., Voloshin, A.L. et al. 2014. Spatio-temporal characteristics of vegetation cover of arid and semiarid climatic zones in mongolia on the basis of vegetation index NDVI. Arid Ecosyst 4, 61–68. https://doi.org/10.1134/S2079096114020115

·         W. Zhang, Z. Zhang, S. Hu, R. Xu and F. Sun, "Analysis of Vegetation Coverage Changes in Inner Mongolia with MODIS NDVI Images," 2012 2nd International Conference on Remote Sensing, Environment and Transportation Engineering, Nanjing, China, 2012, pp. 1-4, https://doi.org/10.1109/RSETE.2012.6260395.

Author Response

Dear reviewer:
Greetings!
Thank you very much for your careful and professional review of the manuscript, your comments are very important to this paper and to me personally. I will answer your comments in the following paragraphs:
1. The problems with the resolution of images 3, 4, 6, 7, and 8 have been corrected.
2. The order of the Discussion and Conclusion sections in Part IV has been switched.
3. For the references you provided, I found them very helpful after I read them carefully and added some of the articles to the references.
If there are still flaws in the revised results, I hope you will continue to give me your advice. Thank you again for your review, and I wish you a happy life.

Reviewer 3 Report

Dear authors,

thank you for your work. Unfortunately, some critical issues need to be solved. Please check the structure of the paper and the references. Attached you find my suggestions.

Comments for author File: Comments.pdf

Author Response

Dear reviewer:

Greetings!

      Thank you very much for your careful and professional review of the manuscript, your comments are very important to this paper and to me personally. I will answer your comments in the following paragraphs:

1. The article centers on the vegetation cover change on the Tibetan Plateau, and the innovation lies in the following: (1) Geographic location innovation, the Tibetan Plateau plays a very significant role as an indicator of global climate change, and there are very few domestic and international research results on the vegetation cover change on the Tibetan Plateau, even if there is one, it mainly focuses on the correlation of vegetation cover with rainfall and temperature, and there is a lack of consideration of the geographic conditions and anthropogenic factors. There is a lack of consideration of geographic conditions and anthropogenic factors. Although the consideration of anthropogenic factors in this paper has some limitations, such as forest fires, etc., it is still of high value as a guide for the current research development. (2) NDVI is considered one of the most important and widely used parameters in global vegetation studies.NDVI can be used to detect changes in forest structure, such as changes in tree density, and to identify areas of forest regeneration. It can also be used to monitor the impact of forestry management practices (i.e., logging, thinning and prescribed burning) on the overall growth of forest ecosystems. The index is very effective in studying spatial and temporal changes in forest dynamics in remote areas that are otherwise difficult to access. (3) NDVI (Normalized Vegetation Index) is closely related to forests as an index used to assess the greenness and growth of vegetation. A single analysis of the trend of a certain vegetation may not be the main purpose of this article, which tends to analyze the changes in the state of all vegetation on a large scale, and forests, as the most important component of vegetation, have a very significant response to the results of the study, in view of which I believe that this article is fully in line with the requirements of the journal.
2. (1) You mentioned meteorological data in Materials and Methods, why not climatic data, here is my terminology error, ignoring that climatic data is the data of climatic characteristics and trends on a relatively long time scale, this issue has been revised in the article. (2) You mentioned that the data sources and datasets are not clearly presented, the article does introduce more general information in the body of the article, and more information, including the DOI numbers, are shown in detail in the corresponding references.
3. (1) You mentioned the explanation of the workflow, the technology roadmap is indeed a very good way to show, the technical route of this article is relatively clear, the methods used are also more mature, I think if too much elaboration may reduce the conciseness of the article. (2) Your question about the accuracy of the results is very understandable, probably because of the relatively simple explanation of the research methodology. Therefore, in order to ensure the conciseness of the article and verify the accuracy of the conclusions in this paper, I compared my results with publications by other authors in the same region during the research process, as well as with publications on the spatial and temporal changes of vegetation cover in other regions, and the results of the comparison have a strong correlation.
4. (1) Your thought-provoking question at the end of the article, I found that the  analysis of the limitations of the current state of the research is indeed very shallow, especially the lack of outlook for future research, in view of this I added the limitations of the core method of this paper, geodetector method, and the lack of research on anthropogenic drivers in the Discussion section of the article, including forest fires, land use and land cover change, and forest resource development, forest degradation, and other factors, which will also serve as the focus direction of my next research. (2) Because of the maturity of the research methodology and the openness of the data sources, the research in this paper is highly reproducible.

5. The references you recommended have been read and completed, and found that there are a lot of worthwhile references, so they were partially added to the references.

       Revision of the results if there are still flaws, but also hope that you continue to be unstinting, thank you again for your review, I wish you a happy life.

Reviewer 4 Report

Dear Authors,

I have had the pleasure to review the revised manuscript entitled “Analysis of spatial and temporal changes in vegetation cover and driving forces on the Qinghai-Tibet Plateau”.

I have found the manuscript to be interesting. The study is addressing an important topic, especially for the study context. Besides, the authors are using a quite appropriate methodology which is well supporting the findings reported.
Although I do have a very positive opinion of the manuscript as it stands, I believe a bit more work should be done. In this regard, I have provided a few specific comments (attache to this report) to guide the authors in improving the overall quality of the paper.

My definitive opinion is “Major Revision”.

Comments for author File: Comments.pdf

The English is fine, only moderate editing is required.

Author Response

Dear reviewer:

Greetings!

Thank you very much for your careful and professional review of the manuscript, your comments are very important to this paper and to me personally. I will answer your comments in the following paragraphs:

1. For the modifications of the abstract, including Commented A1~A6, I have made all the modifications with reference to your comments. A1 suggested present tense grammar has been modified, and a concluding sentence has been added at the end of the paper. A2 refined the meteorological data. A3 detailed the data belong to the annualized data. A4 used the full name of the method. A5 modified the name error. A6 modified the statements.
2. Changes to the introduction section, including Commented A7~A11, have been made in their entirety.A7,A8The literature you provided was helpful to this article and has been added to the reference list.A9,A10Nomenclature errors have been corrected.A11The redundant text has been redacted.
3. For the data sources and research methodology section of the revised opinions, including Commented A12~A22, basically made changes, except for A21 (4) part of a slightly different view. a12 for the semantics of the part of the original text is not clear enough to do a further description. a13 for the picture has been added to the grid of latitude and longitude, the data sources in the section of the 2.2 Data Sources has a detailed description. a14 for the data resolution information has been added. The resolution information of the data has been added. A15 The text of this paragraph has been modified to reflect the fact that the data were processed at the data source when the data were acquired, not by the authors themselves. A16 Typographical errors have been corrected. A17 The correlation type of person correlation has been described in detail. A18 Further details have been provided on the fact that all the data have been re-sampled to a resolution of 1 km, which is the same as the 1 km resolution of both the NDVI and the meteorological data. A19 has numbered all equations. A20 has changed the description to annual data. A21(1) and (2) I didn't think of the MK trend test before trend analysis, but after reviewing the data, I think you have a good point, and I have made corrections accordingly. A21(3) I think your suggestion of eliminating the MK trend test because of its popularity is very reasonable. A21(4) You mentioned that the trend test is affected by autocorrelation, which is indeed the case after checking the information, and autocorrelation detection can be a useful step for analyzing the spatial and temporal trends of NDVI. However, the NDVI data obtained in this paper have already been preprocessed and corrected by the data provider, and since this process is not necessary and the focus of this paper is on the analysis of driving forces, I hope you can understand that I have simplified the content here in order to reduce the length of this section.A22 The Microsoft Word software used in this process has been introduced in the original article.
4. All the modifications to the results section, including Commented A23~A37, have been made.A23 used a better title.A24 caused a misunderstanding due to my wrong title of the picture.In fact, all the four graphs are the trend graphs of NDVI, and the following three small graphs are analyzed by time segments. Additions have been made to what was missing from the original graphs, but the NDVI data has no units as far as I know, so no units have been added to the Y-axis. Because of the inconsistency in the time segmentation of the data, the same time intervals have been used for the X-axis of the four plots as far as possible, but for the sake of overall aesthetics the time intervals are still somewhat different. A25 The content of the annual growth rate of rainfall and temperature is reflected in image 5, with the description added at the original text and the hypothesis that there is a possible correlation between rainfall, temperature, and NDVI as a way of leading to the following. A26 You proposed to add a panel to display the NDVI probability density curves, due to the Tibetan Plateau's high topographic relief, dramatic climate change, and apparently large differences in vegetation types and surface conditions, large spatial variability may lead to unreliable analytical results, so here I have instead added a graph of the annual changes in four different vegetation cover subregions. A27 A third column has been added to show the average annual growth values. A28 The image has been added to the units, and the complex terminology has been A29 Simplified complex terminology. A30 Modified the nomenclature.A31 Modified the nomenclature.A32 Added an explanation of thresholds.A33 Modified the nomenclature. A34 Used simpler terminology.A35 Modified the problem that some of the pictures had fewer units and incorrect proper nouns.A36 Modified the nomenclature.A37 The limitations of the geodetic detector methodology are discussed in detail in the Discussion of Section 4.1. section.
5. In response to the revisions in the Discussion and Conclusion section, including Commented A38, all revisions were made to update the analysis of the relationship between the Granger causality test and other available correlation tests, explaining in detail the limitations of the Granger causality test. limitations of the Granger causality test.

The above are all the revisions, thank you again for reviewing the paper, which is very helpful to me, especially the part on the relationship between spatial autocorrelation, MK trend test and Theil-Sen Trend. If there are still flaws in the revised results, I hope you will continue to give me your advice. Have a nice life.

Round 2

Reviewer 3 Report

Dear author thank you for your effort in improving the paper. Some minor misspellings:

- Row 24: "the" is duplicated;

- Row 72: "'?" must be canceled;

- Row 198: "In this study, we based on Microsoft Word software used a factor detection tool...". I don't know, probably something is wrong. Please check this phrase.

- Row 317 (and more): "Climat Factor" is incorrect. Perhaps, you could use "climate", as in row 107.

Author Response

尊敬的审稿人：
您好！
感谢您的宝贵意见。我已经纠正了第 24 行中的语法错误。72. 在第72行，你提到的“？”问题，我想可能是引言的结尾，我做了相应的修改。在第 198 行，我重新组织了你提到的语义问题的语言。在第 317 行中，纠正了许多其他名词错误。
如果修改结果还有瑕疵，希望大家继续给出建议，再次感谢大家的点评，祝大家生活愉快。

Reviewer 4 Report

Dear Authors,

I have reviewed the revised version of your manuscript entitled "Analysis of spatial and temporal changes in vegetation cover and driving forces on the Qinghai-Tibet Plateau". Your efforts in correcting the manuscript based on my initial comments are very much appreciated.

One minor issue, please do no number the points in the conclusion section.

 

The English is fine. Only moderate changes are required.

Author Response

Dear reviewer:
Greetings!
Thank you for your valuable comments, the issues you raised I think can make the article more concise, so I canceled the numbering of the conclusion part.
I hope you will continue to give me your unstinting advice if the revision results are still flawed, thank you again for your review, and have a nice life.