Exploring the Spatio-Temporal Dynamics of Winter Rape on the Middle Reaches of Yangtze River Valley Using Time-Series MODIS Data
Round 1
Reviewer 1 Report
The authors examine the spatial and temporal changes of winter rape production using time-series MODIS data on a specific area in Mainland China. The results show a reduction in both planted area and yield. This reduction may be due to the competition from international trade, among others, and has important economic and policy implications.
I find the issue relevant. Overall the paper is well written and well structured and the discussion and conclusions are clear. However, I think the material and methods and the results sections could be somewhat more carefully explained, especially when it comes to concepts and interpretation of results. I also miss a bit more discussion on the methods used. Why are they appropriate?
I list below some additional minor comments which could improve the paper:
Line 1: Is the article a letter? Abstract: I would suggest stating already in the abstract the time frame in which all the political, economic and productive changes take place. I would also suggest saying what EVI means (instead of using the acronym). Introduction: Line 38: Share of what? Please indicate it. Figure 1: Are there data for a longer period which at least covers the study period? Data on production could also be interesting. The structure of the paper has not been included. I would suggest including it. Materials and methods: Lines 81-82: Is it plausible that a province is missing? Years 2003 and 2015 were selected. Is there any potential implication/drawback as a result of using only these years? I would suggest briefly explaining what NDVI and EVI measure and why it is appropriate to use them in this specific analysis. Why are only EVI data used to construct optimized time-series datasets (lines 105-106)? Please indicate it. Figure 3: Why EVI and not NDVI data are used? What does “after DOY 065” (line 125) mean? I would suggest explaining more clearly the figure. Results: Line 166: There is something missing in “The accuracies of the modeled were…” Lines 176-177: “Except a light increase in Jiangxi Province…”. Is there any possible reason for this increase? Figure 7 (a): It is difficult to distinguish the bar colors. I suggest using more different shades of green. Line 207: The authors write 2005 instead of 2015. Discussion: I cannot see how reason two (lines 230-236) can be a result of international trade. In my opinion, it is more related to domestic reasons (even if it impacts on production costs which in turn affects cost disadvantages). I would suggest somewhat nuancing this part because it does not link well with the sentence in lines 222-223. Lines 257-261 refer to some limitations of the study. I would suggest introducing it very briefly in a different way to let the reader know that the subject is changing. References: I would avoid expressions such as: “the method proposed by [14]” (line 111) and would suggest introducing the references (or the numbers) in all cases in a more subtle way. Reference numbers are not correctly ordered in the body of the text. Please check.Author Response
The authors examine the spatial and temporal changes of winter rape production using time-series MODIS data on a specific area in Mainland China. The results show a reduction in both planted area and yield. This reduction may be due to the competition from international trade, among others, and has important economic and policy implications.
I find the issue relevant. Overall the paper is well written and well structured and the discussion and conclusions are clear. However, I think the material and methods and the results sections could be somewhat more carefully explained, especially when it comes to concepts and interpretation of results. I also miss a bit more discussion on the methods used. Why are they appropriate?
Answer: Essential changes have been made to the manuscript in this round. More details were added to the Material section. In the Method section, we made a big change by adding a flowchart describing the method, discussing the advantages of the method, and moving some sentences unrelated to this part to Sub-section 3.1. In the Result section, minor errors and inaccurate expressions are also corrected to help the interpretation of results.
I list below some additional minor comments which could improve the paper:
Line 1: Is the article a letter?
Answer: Yes, it’s a letter.
Abstract: I would suggest stating already in the abstract the time frame in which all the political, economic and productive changes take place. I would also suggest saying what EVI means (instead of using the acronym).
Answer: The time frame (including the time the experimental materials covered, and the time some countries got involved in the trade issues) has been added to the abstract. The full name of EVI has been added.
Introduction: Line 38: Share of what? Please indicate it.
Answer: Rapeseed share in China. It has been added to the Introduction.
Figure 1: Are there data for a longer period which at least covers the study period? Data on production could also be interesting. The structure of the paper has not been included. I would suggest including it.
Answer: We have downloaded the latest version data from the FAO website and redraw the figure. Thank you for your suggestion.
Materials and methods: Lines 81-82: Is it plausible that a province is missing?
Answer: Anhui Province was missing and has been added to the manuscript. Moreover, only parts of those provinces (except Hubei Province) were included because winter rape is concentrated on these areas within MYR.
Years 2003 and 2015 were selected. Is there any potential implication/drawback as a result of using only these years?
Answer: Yes, there are some limitations of using only two years data. This is acceptable because we can get high-quality sampling data only in these years, and the time frame covered more than one decade and can meet the requirement of observing the trend of winter rape distribution.
I would suggest briefly explaining what NDVI and EVI measure and why it is appropriate to use them in this specific analysis. Why are only EVI data used to construct optimized time-series datasets (lines 105-106)? Please indicate it.
Answer: Two sentences have been added to the manuscript to indicate it more clearly. (Vegetation index measure the density of live green vegetations, and time-series vegetation index capture the phenological differences of varied land-cover types. EVI layer was used in our study because it overcome the saturation problems better compared to NDVI.)
Figure 3: Why EVI and not NDVI data are used? What does “after DOY 065” (line 125) mean? I would suggest explaining more clearly the figure.
Answer: The EVI issue has been stated in Sub-section 2.2.
DOY means Julian Day of a year, the number of days since the beginning of the year. We have made some modification to the manuscript and also the title of the figure.
Results: Line 166: There is something missing in “The accuracies of the modeled were…”
Answer: Thank you for pointing out the missing. It is …modeled result…, not …modeled….
Lines 176-177: “Except a light increase in Jiangxi Province…”. Is there any possible reason for this increase?
Answer: This slight increase can be partly explained as the boom of rapeseed-flower-tourism in Jiangxi Province. This sentence has been added to the manuscript.
Figure 7 (a): It is difficult to distinguish the bar colors. I suggest using more different shades of green.
Answer: The figure has been redrawn to make the bars more distinguishable.
Line 207: The authors write 2005 instead of 2015.
Answer: Thank you for finding the error.
Discussion: I cannot see how reason two (lines 230-236) can be a result of international trade. In my opinion, it is more related to domestic reasons (even if it impacts on production costs which in turn affects cost disadvantages). I would suggest somewhat nuancing this part because it does not link well with the sentence in lines 222-223.
Answer: Substantial revision has been made to this part. ‘International rapeseed trade…’ is no longer taken as the main idea of the Discussion section, but one factor to support the conclusion. Two factors--international rapeseed trade and domestic labor force shortage are regarded as external and internal reasons to explain the shrinkage of winter rape planting areas on the MYR.
Lines 257-261 refer to some limitations of the study. I would suggest introducing it very briefly in a different way to let the reader know that the subject is changing.
Answer: Limitations of the study and uncertainty of the winter rape maps has been moved to Sub-section 3.1 to make the Discussion more focused. Can you agree with this change? Your further comments are highly appreciated.
References: I would avoid expressions such as: “the method proposed by [14]” (line 111) and would suggest introducing the references (or the numbers) in all cases in a more subtle way. Reference numbers are not correctly ordered in the body of the text. Please check.
Answer: The expression has been revised. The references have been reordered.
Reviewer 2 Report
Abstract: not clear; it is not self-explanatory;
Introduction: No academic literature related to winter rape marketing chains analysis is provided. The assmution:” This large import of soybean from international market has made great pressure on China's domestic soybean cultivation and we see a substantial shrinkage in soybean planting areas.” is in this case misleading.
Material and Methods: better explanations for the source of data and methods are needed. Advantages/disadvantages of the research methodology.
Results and discussion:
The results show that the area allocated to the winter rape cultivation decrease. Discussions are only assumptions. There is no evident link between the main results and the discussions. Results should also focus on other causes of this decrease.
Author Response
Abstract: not clear; it is not self-explanatory;
Introduction: No academic literature related to winter rape marketing chains analysis is provided. The assmution:” This large import of soybean from international market has made great pressure on China's domestic soybean cultivation and we see a substantial shrinkage in soybean planting areas.” is in this case misleading.
Answer: The collapse of soybean system in Northeast China is well known in Chinese agricultural sector. There are many literatures discussing this issue (for example, Sun, J.; Wu, W.; Tang, H.; Liu, J. Spatiotemporal patterns of non-genetically modified crops in the era of expansion of genetically modified food. Scientific reports 2015, 5, 14180. Hairong, Y.; Yiyuan, C.; Bun, K.H. China's soybean crisis: the logic of modernization and its discontents. The Journal of Peasant Studies 2016, 43, 373-395.). In this version more related academic literatures are included to support the Introduction.
Material and Methods: better explanations for the source of data and methods are needed. Advantages/disadvantages of the research methodology.
Answer: More descriptions of the data (such phenological differences with in time-series vegetation index) were added. The advantages/limitations were discussed in Sub-section 2.3 and Sub-section 3.1 respectively.
Results and discussion: The results show that the area allocated to the winter rape cultivation decrease. Discussions are only assumptions. There is no evident link between the main results and the discussions. Results should also focus on other causes of this decrease.
Answer: Substantial revision has been made to this part. ‘International rapeseed trade…’ is no longer taken as the main idea of the Discussion section, but one factor of the shrinkage of winter rape. International rapeseed trade and domestic labor force shortage are regarded as external and internal factors to explain the shrinkage of winter rape planting areas on the MYR.
Reviewer 3 Report
Journal: Sustainability (ISSN 2071-1050)
Manuscript ID: sustainability-651721-peer-review-v1
Number of Pages: 11
Title: Exploring the Spatio-temporal Dynamics of Winter Rape on the Middle Reaches of Yangtze River Valley Using Time-series MODIS Data
Overall
This article reinvestigates the issues of Spatio-temporal dynamics of winter rape on the middle reaches of yangtze river valley with time-series data.
The author(s)’ results show that there is an essential decrease in both number and density of winter rape patches under the opening global rapeseed market. There are significant hotspots of winter rape gain and loss, within which the loss 26 dominated the trend.
The significant cost advantage of winter rape in the international market may largely reduce the domestic cultivation in China through telecoupling effects.
General comment –
The article is successful and in some scale appropriate in its aim - in the sense that it uses a very different and a dataset to replicate the existing results. I, however, feel that the marginal contribution of this replication is not high enough for a specialized journal such as Sustainability. This conclusion is drawn mainly three reasons. (i) The manuscript has no theoretically backup in the literature; (ii) whereas the empirics only reaffirms the few results by normal intuition. (iii) The empirical analyses on spatio-temporal dynamics have issues and should be give more direct evidence to discuss the relationship between variables.
Therefore, the current version of the paper is not well prepared and need major revisions for further improvements.
Author Response
General comment –
The article is successful and in some scale appropriate in its aim - in the sense that it uses a very different and a dataset to replicate the existing results. I, however, feel that the marginal contribution of this replication is not high enough for a specialized journal such as Sustainability. This conclusion is drawn mainly three reasons. (i) The manuscript has no theoretically backup in the literature; (ii) whereas the empirics only reaffirms the few results by normal intuition. (iii) The empirical analyses on spatio-temporal dynamics have issues and should be give more direct evidence to discuss the relationship between variables.
Answer: Substantial revision has been made to the manuscript in this round. (1) More literatures were included in to further understand the research background. (2) More data (including rapeseed imports, labor cost etc.) was analyzed to provide the evidence. (3) The Discussion section was almost rewritten, ‘International rapeseed trade…’ is no longer taken as the main idea of the Discussion section, but one factor of the shrinkage of winter rape. International rapeseed trade and domestic labor force shortage are regarded as external and internal factors to explain the shrinkage of winter rape planting areas on the MYR.
Round 2
Reviewer 2 Report
Introduction: the literature about winter rape marketing chains analysis is still very limitative;
Results: only partially ameliorated;
Author Response
We made revision carefully in this round. We think the research was meaningful but the result was not perfect because we are remote sensing guys and have no economics background. Thank you.
Reviewer 2
Comments and Suggestions for Authors
Introduction: the literature about winter rape marketing chains analysis is still very limitative;
Answer: The first paragraph was revised by adding more marketing chains analysis of soybean and more literate references. The story of soybean was more complete. It was then followed by the question of whether the story of soybean has happened or will happen to winter rape. Marketing chains analysis of rapeseed was put in the Discussion section. Thank you.
Results: only partially ameliorated;
Answer: The Discussion was revised by comparing the trade competitiveness index of rapeseed among the five top rapeseed producing countries. We believe that external and internal factors have recently driven the decline in winter rape cultivation. We hope the conclusion was supported well. Thank you.
Round 3
Reviewer 2 Report
The paper was reviewed.
Author Response
Thank your work and time on this manuscript.
