The Changes in Cropland Pattern Enhanced Carbon Storage in Northwest China

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I have made review of this manuscript. However, there are several issues in the current form which requires substantial revision. According to my understanding, the concept of the manuscript is up to the mark, but the development is poor. Plenty of flaws are there in methods and are not well described as well. I am aware that there is a great effort behind the manuscript.

Please re-consider what the findings are and what can be reasonable to be discussed. Also, please re-consider the wording in the conclusion section as well.

Add more refference to suport  discussion 

SPECIFIC COMMENTS:

1.      Improve the conclusion part in the abstract.

2.      Don't use the words in the topic as key words and arrange alphabetical order (Line 36).

3.      “Line number 49” what do you mean by word IPBES.

4.      “Line number 59, 127” Write chemical formulas in formulation style

5.      “Line number 150” No need to space between value and unit.

6.      “Line number 157, 159, 196, 199” This is quite confusing to understand. In which category does 2010 include?  2000 to 2010 or 2010 to 2020.

7.      “Line number 209” Is this your assumption?

8.      “Line number 236” Value should be correct as 3.58 x10⁶, and “line number 249”value should be correct as 6.71 x 10⁵

9.      “Line number 249” 207 or 2007? It should be correct as 2007.

10.  “Line number 259” The figures in the result section you have shown as Figure 3 are not clear. It would be better if clear figures could be included.

11.  “Line number 270” In figure 04a and 04b, Which figure shows the data for 2010? It is mentioned in both. It is misleading information. It should be correct as 2000 to 2009 and 2010 to 2020 or 2000 to 2010 and 2011 to 2020

12.  “Line number 279” Figure 05 also has same problem. Rearrange figures.

13.  “Line number 367”km2  should correct as follows km²

 

14.  “Line number 436” Value should be correct as 2.03 x10⁶

Please check attached file

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Comments and Suggestions for Authors

I have made review of this manuscript. However, there are several issues in the current form which requires substantial revision. According to my understanding, the concept of the manuscript is up to the mark, but the development is poor. Plenty of flaws are there in methods and are not well described as well. I am aware that there is a great effort behind the manuscript. Please re-consider what the findings are and what can be reasonable to be discussed. Also, please re-consider the wording in the conclusion section as well. Add more reference to support discussion

Response: We want to thank the reviewer for their constructive feedback and insightful comments on our manuscript. As you suggested, we have developed further into the discussion section and made changes. At the same time, some references are added to support to improve the quality of the text. The abstract and conclusion have also been revised accordingly. As for method, we referred mainly to the following two references and also made revised accordingly: [1] Zhu, E., Deng, J., Zhou, M., Gan, M., et al. 2018. Carbon emissions induced by land-use and land-cover change from 1970 to 2010 in zhejiang, China. Science of The Total Environment, 646(PT.1-1660), 930-939. [2] Lai, L., Huang, X., Yang, H.; et al. 2016. Carbon emissions from land-use change and management in China between 1990 and 2010. Science Advances, 2(11): e1601063.

We hope that our changes meet with your full approval. Revised portions are marked in red.

SPECIFIC COMMENTS:

1. Improve the conclusion part in the abstract.

Response: Thank you for the pertinent suggestion. We have revised and further improved the conclusion part in the abstract in Line 28 to 31.

2. Don't use the words in the topic as key words and arrange alphabetical order (Line 36).

Response: Thank you for the pertinent suggestion. We have revised key words and rearranged alphabetical order in Line 32.

 

3.“Line number 49” what do you mean by word IPBES.

Response: We are sorry for our unclear expression. We have revised this sentence to express clearly in Line 45 to 47.

4.“Line number 59, 127” Write chemical formulas in formulation style

Response: We are sorry for our careless. We have revised chemical formulas in formulation style in Line 55 and Line 122.

5.“Line number 150” No need to space between value and unit.

Response: Thank you for the pertinent suggestion. We have deleted the space.

6.“Line number 157, 159, 196, 199”This is quite confusing to understand. In which category does 2010 include? 2000 to 2010 or 2010 to 2020.

Response: Thanks for your insightful comments. We are sorry for our unclear expression. We have change “2000-2010” to “2000 to 2010”, and “2010-2020” to “2010 to 2020” in Line 151, 159 and Line 191,195.

7.“Line number 209” Is this your assumption?

Response: Thanks for your insightful comments. We have deleted this sentence and further described this assumption in introduction part in Line 101-105: We hypothesized that the cropland biomass carbon after cropland expansion was zero since crops are harvested each year being their carbon is quickly returned to the atmosphere via oxidation (burning or decomposition) that do not represent a permanent C stock, and the changes in cropland pattern would result in a carbon sequestration.

8. “Line number 236” Value should be correct as 3.58 x10⁶, and “line number 249”value should be correct as 6.71 x 10⁵

Response: We are sorry for our careless. We have corrected these values in Line 232 and Line 247 and also checked in full text.

9.“Line number 249” 207 or 2007? It should be correct as 2007.

Response: We are sorry for our careless. We have corrected this value in Line 246.

10. “Line number 259” The figures in the result section you have shown as Figure 3 are not clear. It would be better if clear figures could be included.

Response: Thanks for your insightful comments. We have replaced with a clearer figure 3.

11.“Line number 270” In figure 04a and 04b, Which figure shows the data for 2010? It is mentioned in both. It is misleading information. It should be correct as 2000 to 2009 and 2010 to 2020 or 2000 to 2010 and 2011 to 2020

Response: Thanks for your insightful comments. We have corrected figure 4 to “2000 to 2010 and 2011 to 2020”.

12.“Line number 279” Figure 05 also has same problem. Rearrange figures.

Response: Thanks for your insightful comments. We have corrected figure 5 to “2000 to 2010 and 2011 to 2020”.

13.“Line number 367”km2  should correct as follows km²

Response: We are sorry for our careless. We have corrected this value in Line 365.

14.“Line number 436” Value should be correct as 2.03 x10⁶

Response: We are sorry for our careless. We have revised this sentence in Line 423-425. 

 

Reviewer 2 Report

Comments and Suggestions for Authors

Overall, the manuscript is interesting and valuable. Please remove the errors and try to comment on some of my thoughts - it may improve the quality of the manuscript. The list of problems is below:

1. Some of the keywords are a repetition of the content of the manuscript title. Please analyze the keyword change

2. Line 49, please enter the name of the institution, not the abbreviation

3. Line 67-71 the literature review is selective and does not take into account recently published research results (in MDPI publications), indicating that CO2 emissions from forest soils may be even higher than from agricultural fields. The problem seems to be more complex and is not limited only to the increase in emissions and carbon retention in the soil as a result of land use change. It seems that this part of the manuscript chapter could be supplemented with a deeper analysis.

4. Line 209-210, please justify your assumption in detail

5. Line 214 superscript

6. Line 215 superscript unnecessary

7. Table 1, what is striking is the clearly lower grassland vegetation carbon density than forest and cropland. Do the obtained results raise any reservations or doubts from the authors of the manuscript as to the correctness of the mathematical model and/or the assumptions made (taking into account the biomass productivity of these environments)?

8. Lines 226-228 superscript is unnecessary

9. Line 258 of the legend in the drawings is illegible

10. Figure 4, Figures 6 and 7 and 8 descriptions of the OY axis - no spaces

11. Line 316 and 326 no spaces

12. Line 373 I don't understand: "(about 1.9%/a, our study was 0.74%/a)"

13. Line 405 the word in the middle of the sentence is capitalized (?).

As I wrote in the review, I have no fundamental comments on the methodology or research results obtained.  The authors of the manuscript assessed the state of the environment, stating indisputable facts (reduced carbon and nutrient content in the soil after repeated floods).  My only doubt is the interpretation of the research results, or rather the explanation that the main reason for the stated state of affairs is denitrification.  This must be verified and either this view will be supported by numerous citations, or my comments will encourage them to think more deeply.  The suggestion of surface runoff is not accidental.  Therefore, I believe that correcting the Discussion section is crucial for the quality of this manuscript and correcting it will automatically improve the conclusions and abstract.

Author Response

Comments and Suggestions for Authors

Overall, the manuscript is interesting and valuable. Please remove the errors and try to comment on some of my thoughts - it may improve the quality of the manuscript. The list of problems is below:

1. Some of the keywords are a repetition of the content of the manuscript title. Please analyze the keyword change

Response: Thank you for the pertinent suggestion. We have revised key words and rearranged alphabetical order in Line 32.

 

2. Line 49, please enter the name of the institution, not the abbreviation

Response: We are sorry for our unclear expression. We have revised this sentence to express clearly in Line 45.

3. Line 67-71 the literature review is selective and does not take into account recently published research results (in MDPI publications), indicating that CO₂emissions from forest soils may be even higher than from agricultural fields. The problem seems to be more complex and is not limited only to the increase in emissions and carbon retention in the soil as a result of land use change. It seems that this part of the manuscript chapter could be supplemented with a deeper analysis.

Response: Thank you for the pertinent suggestion. We are sorry for our unclear expression. Here, what we're trying to say here is that in general, conversion of forests, grassland to cropland, leading to a major loss of carbon storage. Of course, due to the differences in natural state in some areas, for example, the conversion of grassland into farmland in desert areas may lead to the increase of carbon storage. We have added recently published research results (in MDPI publications) in Line 569-574.

4. Line 209-210, please justify your assumption in detail

Response: Thanks for your insightful comments. We have deleted this sentence and further described this assumption in introduction part in Line 101-105: We hypothesized that the cropland biomass carbon after cropland expansion was zero since crops are harvested each year being their carbon is quickly returned to the atmosphere via oxidation (burning or decomposition) that do not represent a permanent C stock, and the changes in cropland pattern would result in a carbon sequestration.

5. Line 214 superscript

Response: Thank you for the pertinent suggestion. We have revised this superscript in Line 210.

6. Line 215 superscript unnecessary

Response: Thank you for the pertinent suggestion. We have revised this superscript in Line 212.

7. Table 1, what is striking is the clearly lower grassland vegetation carbon density than forest and cropland. Do the obtained results raise any reservations or doubts from the authors of the manuscript as to the correctness of the mathematical model and/or the assumptions made (taking into account the biomass productivity of these environments)?

Response: In Northwest China, the grassland types are mainly desert grassland and other grassland types with low coverage, so the carbon density is lower than that of forest and farmland. The table 1 shows the average grassland vegetation carbon density in Northwest China.

8. Lines 226-228 superscript is unnecessary

Response: Thank you for the pertinent suggestion. We have revised this superscript in Line 222-225.

9. Line 258 of the legend in the drawings is illegible

Response: Thanks for your insightful comments. We have replaced with a clearer figure 2.

10. Figure 4, Figures 6 and 7 and 8 descriptions of the OY axis - no spaces

Response: Thanks for your insightful comments. We have revised these parts in figure 4, Figures 6 and 7 and 8.

11. Line 316 and 326 no spaces

Response: Thanks for your insightful comments. We have revised these parts in Line 304, 313, 323.

12. Line 373 I don't understand: "(about 1.9%/a, our study was 0.74%/a)"

Response: Thank you for the pertinent suggestion. We are sorry for our unclear expression. Ju et al. (2018) found that 42,822 km² of cropland were converted into built-up land in China, accounting for 43.8% of total cropland loss area during 1987-2010, meaning that cropland to built-up accounts for total cropland loss is about 1.9% one year. In our study, cropland to built-up accounts for total cropland loss is about 0.74% one year.

13. Line 405 the word in the middle of the sentence is capitalized (?).

Response: Thanks for your insightful comments. We have revised this sentence to improve the quality of discussion section.

 

As I wrote in the review, I have no fundamental comments on the methodology or research results obtained. The authors of the manuscript assessed the state of the environment, stating indisputable facts (reduced carbon and nutrient content in the soil after repeated floods). My only doubt is the interpretation of the research results, or rather the explanation that the main reason for the stated state of affairs is denitrification. This must be verified and either this view will be supported by numerous citations, or my comments will encourage them to think more deeply. The suggestion of surface runoff is not accidental. Therefore, I believe that correcting the Discussion section is crucial for the quality of this manuscript and correcting it will automatically improve the conclusions and abstract.

Response: We want to thank the reviewer for their constructive feedback and insightful comments on our manuscript. As you suggested, we have delved further into the discussion section and made changes. At the same time, some references are introduced to support to improve the quality of the text. The abstract and conclusion have also been revised accordingly.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors

the paper is interesting and the data set is broad and well structured.

I only suggest that the Abstract be more representative, containing in the last paragraphs only results and conclusions (with data).

Author Response

Dear Authors

the paper is interesting and the data set is broad and well structured.

I only suggest that the Abstract be more representative, containing in the last paragraphs only results and conclusions (with data).

Response: 

We want to thank the reviewer for their constructive feedback and insightful comments on our manuscript. As you suggested, we have revised abstract part to be more representative containing in the last paragraphs only results and conclusions in Line 15-31.

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Colleagues, thank you for the work you made. Please find bellow some critical remarks:

- in many places the whitespaces before the square brackets symbols are missed – please check and correct;

- lines 16-18 – the sentence is better to be revised and rephrased as the “area of cropland expansion and abandonment increased” phrase is sounding extremely confusing (what is increasing of expansion here(?) – “increasing” and “expansion” are more or less synonymous words in general understanding); also it is not clear in this (when first time looking on the values) way why the area of cropland expansion was increased higher than cropland area was increased(?); also the difference of 3.58 and 2.11 is 1,47, not a 1,48 – please check;

- line 59 – the “2” have to be written in subscript form in “CO2” to ensure conventional formula form;

- figure 2 – the scale bar is better to be redesigned to ensure using of rounded values of scale bar marks (500, 1000 and 2000 for instance); “DEM” in the legend is better to be replaced to “topography height” or “height”;

- lines 127, 367, 371 – the “2” have to be written in superscript form in “km2” to ensure conventional units form;

- lines 178, 180, 181, 183, 191, 192, 195, 197, 204, 205, 214, 226, 227 – the symbols used to refer formulas are disaligned of the lines – please check and correct;

- line 236 – check please and correct the exponentiation symbols;

- line 342 – the dot sign is missed check please.

Author Response

Dear Colleagues, thank you for the work you made. Please find bellow some critical remarks:

1. in many places the whitespaces before the square brackets symbols are missed – please check and correct;

Response: Thanks for your insightful comments. We have checked and corrected this error in full text. 

2. lines 16-18 – the sentence is better to be revised and rephrased as the “area of cropland expansion and abandonment increased” phrase is sounding extremely confusing (what is increasing of expansion here(?) – “increasing” and “expansion” are more or less synonymous words in general understanding); also it is not clear in this (when first time looking on the values) way why the area of cropland expansion was increased higher than cropland area was increased(?); also the difference of 3.58 and 2.11 is 1,47, not a 1,48 – please check;

Response: Thanks for your insightful comments. We are sorry for our unclear expression and have revised this sentence in Line 15-17. The results-indicated that the area of cropland increased by 1.47×10⁶ ha from 2000 to 2020, in that, the area of cropland expansion and abandonment are 3.58×10⁶ and -2.11×10⁶ ha , respectively.

3. line 59 – the “2” have to be written in subscript form in “CO2” to ensure conventional formula form;

Response: Thanks for your insightful comments. We have corrected this error in Line 55.

4. figure 2 – the scale bar is better to be redesigned to ensure using of rounded values of scale bar marks (500, 1000 and 2000 for instance); “DEM” in the legend is better to be replaced to “topography height” or “height”;

Response: Thanks for your insightful comments. We have corrected this part in figure 2. the scale bar is redesigned to ensure using of rounded values of scale bar marks (500, 1000 and 2000); “DEM” in the legend is replaced to “height”;

5. lines 127, 367, 371 – the “2” have to be written in superscript form in “km²” to ensure conventional unit form;

Response: Thanks for your insightful comments. We have checked and corrected in Line 122, 365, 370 and also revised these errors in full text. 

6. lines 178, 180, 181, 183, 191, 192, 195, 197, 204, 205, 214, 226, 227 – the symbols used to refer formulas are disaligned of the lines – please check and correct;

Response: Thanks for your insightful comments. We checked and corrected the symbols and lines of the reference formula to make them consistent in Line 173-210.

7. line 236 – check please and correct the exponentiation symbols;

Response: Thanks for your insightful comments. We have corrected in Line 233 and also revised these errors in full text.

8. line 342 – the dot sign is missed check please.

Response: Thanks for your insightful comments. We have added the dot sign in Line 339.