Effect of Mosses and Long-Term N Addition on δ¹³C and δ¹⁸O Values of Respired CO₂ Under a Temperate Forest Floor

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comments

In general, this is an interesting manuscript with lots of analyses.  The way the statistics are described and interpreted is a bit confusing. For example lines 299-302 it says: “Compared with those with the removal of mosses, δ13C values of respired CO2 in the control and the low N treatment with mosses were, on average, reduced by approximately 1.03‰ and 1.06‰, which were significantly larger than that in the moss-covered plots treated at a high N dose (0.60‰) (P < 0.05)”,  —but in the table 3 Treatment has no main effect and there is no significant moss × Treatment effect.  So, I’m not sure what you are saying here.

Again, in lines 271-272, it says: “This indicated that on average, the presence of mosses contributed to approximately 17% and 13% to the soil CO2 and CH4 fluxes under the moss-covered forest floors at a given duration, respectively” —but according to the table the difference in CO₂ flux was not significantly different.

Is it possible instead of doing multiple models and ANOVA and correlation analyses to reduce everything into one model as much as possible and then you could more clearly articulate what are the significant effects vs. what are not?

Also, I have suggested a few places where the wording is unclear, I would recommend, in addition to fixing the things I have indicated below, to also carefully proofread the final text one more time.

Specific Comments

Abstract: It is unclear how both of these statements can be correct as they seem contradictory: “The low N treatment amplified the moss-induced δ¹³C depletion, and minimized δ¹⁸O values of respired CO₂”, and “No significant interactions were observed between mosses and N levels on the δ¹³C or δ¹⁸O values.”

Abstract does not indicate what the effect of the treatments on the fluxes was. I would encourage you to add a sentence describing these.

What is the ¹⁸O of the water? Isn’t that a pretty strong driver of the CO₂ δ¹⁸O?

Line 159: suggested revision: “added N corresponded to twice the”

Line 166: suggested revision: “an equal amount of water was added to the control plots”.

Line 168: it’s not clear what “annually dominated” means?

Line 169: not clear what “certify” in this context means.

Line 213: it’s difficult to tell from the picture if the chamber is opaque or not, i.e. is this light flux or dark flux?

Line 220: I don’t think “certify” is quite the right word here.

Line 226: do you have a citation for this method?

Line 235: I think this should be “specific” rather than “special”.

Line 270: suggest replacing “varied” with “decreased”

Line 274: any thoughts on why the CH₄ flux decreased when the mosses were removed?

Line 299: revise: “Compared with those with the”

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The work is very interesting. A high level of research is represented. The methodology is well described. Comments mainly concern editorial errors and discussion. The discussion repeats a lot of information from the description of the results. No clear comparison with results of other authors. References need to be rewritten.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Please refer to the attachment.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Manuscript much improved. Just a small detail 

Line 112: "...input, can..."

Author Response

We have made some corrections by considering the reviewer's comments. The quality of Figures and Tables was improved.