Effect of Changes in Throughfall on Soil Respiration in Global Forest Ecosystems: A Meta-Analysis
Round 1
Reviewer 1 Report (Previous Reviewer 1)
I have read revised version of paper carefully, Now the paper could be accepted for the publication.
Best Regards
Author Response
Thanks a lot for the reviewer' kind encouragement.
Reviewer 2 Report (Previous Reviewer 2)
Dear Author,
I think the author undertakes an important study on throughfall effect on the soil respiration. This study is rather an overview of other research than an original research, and this is how it was stated.
I think the author made a comprehensive review of the subject on throughfall effect on the soil respiration that has a good potential to be published. However author notified about a well known moisture effect on soil respiration ("A previous meta-analysis showed that decreased precipitation across all terrestrial ecosystems reduced soil respiration by 12%, whereas increased precipitation increased soil respiration by 45% [34]." and "Soil CO2 emissions usually have a peak under moderate soil moisture condition and decrease when soil moisture becomes either relatively wetter or drier, especially in tropical forests [25,41-43].") that should be somehow clearly connected or untangled to-from the throughfall effect he studies. From the first glance it seems that the the throughfall and precipitation effect should be directly correlated.
Sincerely yours
Author Response
As mentioned in the reviewer's comment, there were some relationships between the throughfall and precipitation effect. Normally, throughfall (TF) is much larger than stemflow as a component of total precipitation under forest canopy, and the amount of TF input varies with the characteristics of precipitation and the structure of forest ecosystems such as tree species compositions and stand density. In recent decades, precipitation manipulation experiments via TF transferring have widely conducted in forest ecosystems at different climate zones of the globe. As shown in Figure 8, the readers would understand the potential effects of changes in throughfall on the soil CO2 emission and the key influencing mechanisms involved.
Reviewer 3 Report (Previous Reviewer 4)
In this review paper, the author tried to improve the quality of the manuscript and I believe it is reflected in most of my comments.
Finally, I would like to suggest it is required to confirm the maximum number of words in this abstract due to its long length (more than 470 words).
Comments for author File: 
Comments.pdf
There is no substantial issue with the quality of English writing.
Author Response
Thanks a lot for the reviewer' kind encouragement. The abstract has been refined. At present there are 335 words in the abstract, which would be suitable for the journal Forests.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Dear authors,
Your paper is a interesting review paper and This paper has several weaknesses of which the most important are the lack of data and novelty. There is a great lack of discussion. Your opinion in the discussion of researches is not clear; you just presented the results without comparisons and without adding your experience in this field. The main problem with the manuscript is that there have been a number of relatively recent reviews on Global Forest Ecosystems it is not clear what this manuscript adds to the substantial literature on the matter. I have some revision before reconsider this valuable paper.
The introduction does not help the reader to understand the aims and objectives of the subsequent sections or of the manuscript as a whole. A wide range of areas are covered, sometimes quite rapidly, others in more detail.
Other comments to improved quality of this review paper:
-In abstract, the materials mentioned in the sections of general information is not related to this subheading
- A good review can not only summarize the previous research, but also give suggestions/orientations for future studies, which is missing in this manuscript. This review did not have much information about authors view and suggestion.
- The quality of Fig. 1 and 2 is poor and not very informative. Can be redesign.
Best Regards
Reviewer 2 Report
Dear Author,
I think the author undertakes an important study on throughfall effect on the soil respiration. This study is rather an overview of other research than an original research, and this is how it was stated.
I think the author made a comprehensive review of the subject on throughfall effect on the soil respiration that has a good potential to be published. However there is a well known moisture effect on soil respiration that should be somehow clearly connected or untangled from the throughfall effect.
The review is based on the information from other research papers. In the acknowledgement, I didn't find any information on the permission the author obtained from other researchers to use their data for this review. I wonder if this will not contribute to any potential conflict of interest issues.
Sincerely yours
Reviewer 3 Report
Review Report on the Manuscript Number: forests-2318532 Title: Effect of Changes in Throughfall on Soil Respiration in Global Forest Ecosystems: Review and Data Analysis
I have finished my review on the proposed paper " Effect of Changes in Throughfall on Soil Respiration in Global Forest Ecosystems: Review and Data Analysis ".
1. I don't see any innovation and I don't understand how, on the basis of numerical values taken from Thirty-seven studies and an excel database, without some GIS and spatial analysis, the conclusions were obtained. Statistics were used in which only numerical values from studies were used, so I don't think it will be interesting to other readers.
2. The methods employed in this study are empirical statistical methods and have strong regional limitations. Therefore, it is recommended that hydrological models based on physical processes be employed in future studies to overcome the limitations of empirical statistical methods. Physical models are based on the fundamental principles and processes governing the hydrological cycle, making them more widely applicable and less regionally limited.
3. The exclusion of plant species as a variable in this study is not appropriate. Although Forest type may be uniform within the same site, significant differences in Forests can exist between different sites. Plant species is one of the main factors in this studies. Therefore, it is recommended that plant species be included as a variable in future studies.
4. It would be good to add some works about forest ecosystems and their characteristics. Please read references as follows:
Jonas Glatthorn, Peter Annighöfer, Niko Balkenhol…. An interdisciplinary framework to describe and evaluate the functioning of forest ecosystems. Basic and Applied Ecology. Volume 52, May 2021, Pages 1-14.
Misagh Parhizkar , Mahmood Shabanpour, Manuel Esteban Lucas-Borja , Demetrio Antonio Zema, Siyue Li, Nobuaki Tanaka, Artemi Cerda. Effects of length and application rate of rice straw mulch on surface runoff and soil loss under laboratory simulated rainfall. International Journal of Sediment Research 36 (2021) 468e478.
Ke Guo, Bing Wang and Xiang Niu. A Review of Research on Forest Ecosystem Quality Assessment and Prediction Methods. Forests 2023, 14, 317.
Reviewer 4 Report
Overall, this paper is an important topic to provide a better understanding of the amount of throughfall, climate (i.e., temperature and humidity) on soil respiration and author analysis data collected during the last 3 decades with some criteria. However, for the review paper, it is likely required to improve the introduction parts and deeper discussion part by considering: how soil CO2 emissions can be influenced by TF and what is the most significant indicators affecting soil CO2 emissions among forest types, soil properties, TF sizes and climate types. I recommend you add more literature for discussion
I added some specific comments in the attachment.
L1 climate types (or dry condition) and throughfall (or litterfall type) addition?
L2 Review and data analysis together? please confirm it again and clarify the theme of paper (e.g., mini review, scoping review or others).
L12 due to what?
L23 I don't see any significant implication on this review, maybe you can provide some important factors or indicators to affect annual soil CO2 emission (e.g., 1) decreased precipitation; 2) increased or decreased root biomass; 3) increased or decreased soil microbial biomass etc..).
L30 If it is a review paper, I would like to recommend adding sub-sections after the Introduction part such as 1) Result of soil C dynamic after global warming; 2) definition and effect of throughfall in precipitation; 3) annual soil CO2 emission by microbial; 4) soil CO2 emission in different types of global forests etc..
L48 For readers, can you please add some more reasons why increased (or decreased) moisture fosters soil respiration? due to increased microbial biomass and their respiration rate?
L49 Is it a kind of glasshouse or growth chamber experiment with controlled environment?
L52 Did the literatures you found mention the reason why?
L53 Same question, due to high soil moisture and microbial communities?
L54 Can you please explain regarding this again?
L54 What is TF here? throughfall? Please mention full name first.
L58 How is different with increased precipitation?
L60 I think it should be summerised in the abstract as well.
L66 moderate?
L67 Did they mention numeric value of wet and dry condition of soil moisture?
L69 moderate extent?
L73 temperature, humidity or both?
L75 I believe it is needed to be stated in abstract part shortly.
L80 Please clarify each aim of review with numeric values (e.g., 1)to find..; 2) to quantify; 3) to provide or update...)
In addition to this, I recommend you mentioned how many articles you compiled (e.g., 120 publications (90 research publications/case studies and 30 publications of related reviews or background information about the issues at the global scale) in the recent decades).
L90 Use CO2 as you mentioned CO2 before.
L108 I am sorry I cannot see your Appendix (Table S1), so is that mean a field study but TF manipulation under a controlled environment?
L386 Compared with Indonesia?
L531 TF
L546 Pulse-labelling and stable isotope were not conducted on soil respiration and carbon dynamics studies regarding throughfall?
Comments for author File: Comments.pdf
