Spatio-Temporal Variation of Carbon Sources and Sinks in the Loess Plateau under Different Climatic Conditions and Land Use Types

Round 1

Reviewer 1 Report

Well-written paper dealing with variation of carbon sources and sinks in Loess Plateau, China covering last three decades. The data were used from various sources. Authors conclude, that carbon sink in this area has been enhanced with downward trend from S to N. Paper has some limitations in its methodology, which should be written not only in 4.3, but also in Introduction to make the reader clear that some important variables affecting carbon balance are neglected (pollution, ozone, nitrogen, drought etc).

 

line 32: maybe a newer reference to add would be better. This one is too old.

lines 32, 36 and onwards: check manual for authors, references should be as numbers

line 45: ...and emissions - missing here. Even those not primarily emitted. Tropospheric ozone is substantially decreasing terrestrial carbon sink, as you refer later in 4.3. However, I think it should be clearly mentioned here, at least that you do not take this in account. See paper 10.3390/atmos12010082, which you might add here. You should add at least one paragraph about this here.

line 109: define from which years you have the rainfall. Is it year max and min?

line 110: that are not elements. Use different word

line 124: "We used the team of Professor Yang Jie and Huang Xin of Wuhan University" - improper here. You should have them as co-authors or thank them in Acknowledgement. But do not write it here. It is useless information for a reader.

fig 2: upper figure impossible to read. Make the text bigger

fig 4: upper figure impossible to read. Make the text bigger or delete the figure

Discussion: what about nitrogen deposition? With increase of CO2 concentration during your observation period there is interactive effect of CO2 and N - see paper 10.1093/treephys/tpad024. How that might have affected the NEP? Should be in discussion too. At least to show the uncertainties and limitations (4.3) of your study. You can add this reference here.

fig 7: do not add figure to discussion. Should go to Results

 

Some spelling or wording should be checked.

Author Response

Dear editor,

The response letter to the reviewer is attached, please see the attachment. In addition, we have added an author as a co-author, and the author information is supplemented in the article. If you have any questions, please do not hesitate to contact me.

kind regards,

Mi Wang

Author Response File: Author Response.docx

Reviewer 2 Report

Comment for forests-2551522

This manuscript addresses spatial-temporal variation of carbon sources and sinks in the Loess Plateau under different climatic conditions and land use types. I review this manuscript and found that it is easy to read and understand. I also provide comment as follows.

1.      Title and Abstract are suitable that can reflect whole text.

2.      Audiences could understand the background information and significance of this study in Introduction. However, the purposes of this study may not be explicit here. I suggest listing point by point to show the study purpose in the end of Introduction.

3.      Line 188 “2.2. Data：”, sign “：” should be omitted.

4.      Please give a number for each equation. Below equations, “where” should use lower case. Please format the notes of all equations, such as Lines 132, 155.

5.      Line 197, Here points out Fig.S1. However, I could not find this Figure. Please confirm it again.

6.      Figure 6 should have more explanation in context.

7.      In my viewpoints, this manuscript used many equations to predict carbon. Therefore, it might have a limitation in using these equations. Therefore, authors should discuss the accuracy between model and data or limitation of this study in Discussion chapter.

8.      What is the union of Y axis of Figure 7? Please check it!

9.      I also suggest that authors should emphasize the significance of results of this study compared to other references in Discussion chapter.

10.  Conclusion is suitable and I have no further suggestion here.

Overall, this topic is interesting in forestry and I recommend it for publication in Forests after revised.

Author Response

Dear editor,

The response letter to the reviewer is attached, please see the attachment. In addition, we have added an author as a co-author, and the author information is supplemented in the article. If you have any questions, please do not hesitate to contact me.

kind regards,

Mi Wang

Author Response File: Author Response.docx

Reviewer 3 Report

Some further attention to English is warranted e.g. Line 75 presumably soil and vegetation are two factors, Line 186 use analytical as the adjective, Line 192 where the past tense is preferred.

The statement in the Conclusions [that the distributions of the carbon sources and sinks are characterized by apparent vertical zonation; specifically, the carbon sink has a downward trend from south to north] should be reworded. Vertical zonation is usually applied to vertical profiles such as distribution of C sinks with depth in a soil or sequestration in forest strata

English is generally correct, but a few minor errors remain

Author Response

Dear editor,

The response letter to the reviewer is attached, please see the attachment. In addition, we have added an author as a co-author, and the author information is supplemented in the article. If you have any questions, please do not hesitate to contact me.

kind regards,

Mi Wang

Author Response File: Author Response.docx