Microbial Community and Their Potential Functions after Natural Vegetation Restoration in Gullies of Farmland in Mollisols of Northeast China
Round 1
Reviewer 1 Report
The manuscript presents a study of the effects of natural vegetation restoration in gullies of farmland in Mollisols on the microbial diversity, network complexity, and microbial functionality and their functions. I think that the manuscript presents interesting results and the research objectives have been achieved. The study could provide helpful information to enrich the knowledge on microbial community and their potential functions after natural vegetation restoration. Overall, the manuscript is worthy of publication. However, I have few concerns that should be addressed before the paper could be published.
1. In the Materials and Methods part, please supplement the reasons why the Richness (Chao1) was calculated according to the formula rather than other formulas.
2. It is better if the authors could further check the manuscript, especially the format.
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Reviewer 2 Report
The results of the presented study are interesting and provide new knowledge about ecology and functioning of the soil microbial community under natural vegetation restoration of gullies of farmlands in Mollisol region. The authors performed a comprehensive data analysis to show differences in soil microbial composition between gullies and farmlands (NMDS), identify bacterial and fungal biomarkers (LEfSe), size and complexity of microbial co-occurrence networks, correlation and causal relationships between plant, soil microbial and physiochemical properties (SEM, RDA). However, the presentation of the results in the manuscript is poorly structured, which makes them extremely difficult for understanding. So, results related to different sites (Guangrong and Yanmagou), land uses and soil layers are often given in one sentence, that you just get lost in them. Moreover, the different study design between Guangrong and Yanmagou sites further confuses your result interpretation and makes them difficult to understand. Some important results (correlation between plant, soil microbial and physiochemical properties) are given in Discussion section instead of Results one. The manuscript needs significant revision to be more understandable to readers.
Some specific comments:
L. 108-116. Add a clarification for which period the average climatic characteristics are given and from where they are obtained (own measurements or data from weather stations).
L. 122. Latin names of species should be written in italics. Correct it across the manuscript.
L. 139. How was the plant abundance calculated? As a general plant projective cover per plot (1 m × 1 m)? This should be clarified.
L. 135. In the previous section, you gave abbreviations for Guangrong and Yanmagou sites (GR and YM). Either use abbreviations after their first introduction into text or remove them.
L. 159. What is “SM”? Explain the abbreviation.
L. 164-165. Why the soils are free of carbonates? Add a reference to a supporting study or provide other information to confirm this.
L. 146-154. Why was the depth of soil sampling at the Guangdong and Yangmega sites different? How did plots of soil sampling (6 m × 6 m) and plant survey (1 m × 1 m) correspond if they have different sizes?
L. 171-172. It is important information characterizing quantity and availability of nutrients to soil microorganisms. Therefore, the general physicochemical characteristics of the soils should be shortly shown in the results section.
Fig. 1 repeats the data from Fig. 2 (a), so it should be deleted.
Fig. 2 (a, b). “Error bars are twice of the standard error of the mean”. Why is the scale changed for SE? What is the sample size for each group (bar)? What statistical test was used for pairwise comparison of means?
Figure 2 (c). Add a description of the results of this model. What data was used for SEM (sites, land uses, soil layers) and what was the sample size? What are the numbers inside the boxes of endogenous variables (R2)? What do the different arrows mean (solid / dotted, blue / red)? Explain the abbreviations used. Give model fit indexes.
Fig. 3. What soil layers were used for NMDS ordination plot for Guangrong site?
Fig. 4. What soil layer was used for Guangrong site?
Fig. 5. Why is the data shown for only one site? What is the soil layer?
Fig. 6 (a, b). What do different colors mean? What is the soil layer? Why there is no analysis for the Yangmega site?
Table 1 is better to move to supplementary materials.
Author Response
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Reviewer 3 Report
Manuscript id.: land-2032035
Title of the manuscript: Microbial community and their potential functions after natural vegetation restoration in gullies of farmland in mollisols of Northeast China
There are some comments, which are to be incorporated in order to improve the manuscript, as given below:
Introduction
*Hypothesis of the work is not well formulated in the ‘Introduction’ section. The authors did not present a novel justification for carrying out this study. What is the hypothesis of the present study?
*It is insufficient and needs more improvement.
*The novelty of the work must be identified and stated more carefully. The authors have to try to explain why this paper is relevant to the wider readership.
*Authors should show the limitations of previous papers.
Results
*All the abbreviations in Tables and Figures should be explained at the bottom of the Tables/Figures. And similarly in case of supplementary data.
*The soil physico-chemical properties (Table S2) should move in the main manuscript and result should be written accordingly.
Discussion
*Need more improvement. It is too superficial and not a meaningful discussion. Author should try to strengthen the discussion part.
*Put reason why this type of result is obtain.
*Try to avoid mentioning Tables and Figures notation from the discussion section and re-write the discussion accordingly.
Conclusions
*Authors need to rephrase the "Conclusions" section.
*Add some limitations, underscore the scientific value added of your paper, and/or the applicability of your findings/results and future scope of study.
Recommendation: Major revision.
Author Response
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Round 2
Reviewer 2 Report
The authors have improved the article. Nevertheless, the current version of the article needs some clarifications and adjustments.
L. 16. Explain the abbreviation “AP” and “SM” for the abstract.
L. 196. Check and correct the spelling “Bonfferoni test”.
Table 1. Check and correct the correspondence of the depth and position lines for the Guangrong site. In general, the table in this form is difficult to read, so it should be simplified. For example, detailed ANOVA results regarding area and depth effects and their interactions (F and P-values) could be moved to the supplementary materials. Moreover, the average concentrations of nutrients for a thick 0-60 cm layer are considered uninformative, since it doesn’t take into account changes in bulk density along the soil profile. Therefore, I think that the data for the 0-60 cm layer could be removed from the table.
L. 247. Check punctuation in the sentence.
Figure 4. Data visualization using error bars is not suitable as it results in a negative scale in some cases (Serendipitaceae, Agaricales). It is better to use another visualization method, for example, boxplots.
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Reviewer 3 Report
The authors have thoroughly revised the manuscript and it can be accepted in the present from for publication in Land journal.
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