Variability in Crop Response to Spatiotemporal Variation in Climate in China, 1980–2014
Round 1
Reviewer 1 Report
The manuscript examined the temporal and spatial response of three crops, of great importance to filling the food security gap, to climate change in China for more than 30 years. They studied the effect of variation in temperature and precipitation and their relationship to yield and crop types, which should drive the upcoming annual crop rotation models.
The manuscript is accepted in the present form.
Comments:
Reference style in the text and reference list should be checked.
Author Response
Dear Reviewer,
Thank you very much for your recognition of our manuscript entitled “Variability in crop response to spatiotemporal variation of climate in China, 1980-2014” (land-1795372).
Taking into account your suggestion, we have revised the citation format according to the requirements of LAND journal.
Reviewer 2 Report
Dear Author,
Kindly go through the comments I did in the pdf version of your manuscript.
Regards
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Summary
The goal of this article is to understand whether spatio-temporal climate variability affected crops yields (wheat, corn and rice) in China for the 1980-2014 period. To do so, the authors built a linear regression model to analyze the relationships between crop yield and a set of climate variables (temperature, precipitation, PAR) at 0.5° grid resolution. The authors found that rice and corn are more sensitive to climate variations than wheat. Increased temperature was the main driving factor affecting crop yield and the centroid shift of the three crops.
The subject addressed in this paper is worthy of investigation and results are useful. However, I have several concerns and made a few suggestions for improvements.
Major comments
1. Research gap and question:
- In L66., a methodological research gap is introduced: “the tools for relevant analysis are still rare”. I have two comments. The three research questions you have are knowledge-based while as I understand your paper, you also developed a methodological approach to analyze the spatial variability. Therefore, I think you should also include a methodological research question. Furthermore, the L66 sentence is not very clear. I suggest to reformulate like this: “methods to analyze the spatiotemporal variation relationship between climate and yields are still scarce”.
- One of the research questions is: “How much climatic variability has contributed to crop yield variability for each county?” But you conducted the study at a 0.5° grid resolution. The size of the grid and county are different, so I don’t think you should define the resolution at the county level.
2. Method: Why did you choose a p_value of 0.1 (L97)? You can only show weak evidence with such a value. At least you should mention as a limitation in 4.3.
3. Results: I noticed some contradictions, overinterpretation or lack of clarity.
- Fig 1d-f: I understand that you show the trend change of yield (tons/ha). But in the text, L148-149, you talk about “the main increasing area of rice and corn”. It is unclear if here you focus on yield or area of crops. Could you clarify?
- Fig 2: If I understand correctly Fig 2.d, the coefficient of spatial variation is higher for corn than for rice, which is contradictory with what is written L156-157. Or did I misunderstand and if so could you explain?
- L159-160: “Note that there was an abrupt increase in the coefficient of spatial variation for wheat during the 2004-2010” and L163-164: “the spatial distribution of wheat yield became more concentrated during this period”: Those two sentences seem contradictory. As I understood it, higher is the coefficient of spatial variation, more heterogeneous is the spatial distribution of wheat (and not concentrated as for rice). Could you explain?
- L178-182: You indicate the majority of crop harvesting regions did experience the influence of climate variability but R² value are weak to very weak, so I understand this is because of high spatial variations between regions. Could you explain how you determined the % of corn, rice and wheat harvesting regions (73%, 74%, 46%)? I think you used the R² value but I wonder at which level you of the R² you considered that climate variability had an influence. FigA1 is hard to interpret since there is no upper limit on the legend. Could you add the upper limit?
4. Discussion
- L284-285: You present the strong effect of climate variability on crop yield variability at the national scale with high R-squared values. But I don’t understand if you calculated those values with your data or if this is a reference to another article. Please explain.
- In the discussion, you state: “However, with the continuous improvement of water conservancy facilities, the ability to resist short-term disasters is improved”. First, since this is not a result of your research, a reference would be necessary. In addition, I disagree with this statement because short-terms disasters may lead to detrimental impacts (e.g. a drought in critical physiological stage or an unexpected freeze) and there are no necessarily conservancy facilities to face those short-term disasters. Last, improvement of water conservancy facilities has an economic cost and I don’t think the improvement can be continuous, there are limits.
5. I feel that the manuscript would benefit from a native English speaker/professional language editor to go through it. At some points, the use of English and punctuations seems a bit sloppy which can undermine the understanding. Below are some examples but this is not exhaustive since this is not my duty as a reviewer to correct the English.
Examples:
- L16-17: “To better understand the influence of climate variations on crop yield in China would greatly benefit global food security” -> a better understanding…
- L54-55: “In a vast territory, such as China, where feeds 22 percent” -> In a vast territory, such as China that feeds 22 percent…
- L99-100: “To determine where and how much of the interannual variability of crop yields was explained by climate variability”. This sentence is incomplete.
- (...)
Minor comments:
6. I am not from China and I was lost when you refer to the different regions (Yangtze River Basin, Shandong province…). You should add a map showing the locations of the regions you refer to in the paper.
7. Figure 1: What do you mean by “the counties without dots”? I don’t locate them in the maps. L167, replace (d-e) by (d-f)
8. L.41 “are the most common research methods”: to do what?
9. Fig4. The legend in the plot is too small.
10. L386 Change “crop varieties” by “crop species”.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear Author,
Your English language needs to be improved
Regards
Author Response
Dear Reviewer,
Thank you for the critical comments and helpful suggestions on our manuscript entitled “Variability in crop response to spatiotemporal variation of climate in China, 1980-2014” (land-1795372).
According to your advice, this manuscript was edited for proper English language, grammar, punctuation, spelling, and overall style by one or more of the highly qualified native English speaking editors at MDPI.
Attached is a certificate of language editing services.
Regards
Author Response File: Author Response.pdf
