The Early Effect of Plant Density on Soil Physicochemical Attributes and Bacterial and Understory Plant Diversity in Phoebe zhennan Plantations
Round 1
Reviewer 1 Report
The study focuses on evaluation of stand density effect of Phoebe zhennan on diversity and structure of soil bacteria. The manuscript is written well, logically and clear structured. However, to shed light of the obtained results it is needed to add the key information about investigation sites: 1. Land-use history for the studied plots (the founded differences of some soil properties between plots could be related to different approach to land use in the past) 2. Current management practice for studied plots. What is a main reason of changes soil pH, N, SOC between studied plots? It should be explained in discussion section. The results of statistical test should be clarified: in the Tables 2-4 given p-values, which were more than significance level, at the same time the different letters demonstrated significant differences between groups. The conclusion should be formulated. It should be increased quality of figures – difficult to read.
Specific comments:
L.16-33 The abstract needs to re-write based on obtained results. It should be given more information regarding study sites and its feature. It should be given clear explanation of interface mechanism of plant density, soil properties and bacteria structure and diversity.
L.100 What is “S-sampling”?
L.121-124 Give more details about soil analysis.
L.198 As mentioned above in the table soil pH differed between groups (different letters). It should be clarified.
L.329 The highest diversity of bacteria was under 700 stems/ha
Author Response
Dear reviewer,
Thank you for reviewing our manuscript and for the constructive comments, which greatly helped us to improve the manuscript. We have heavily revised our experiments. The manuscript was carefully revised and point-by-point response was listed below. We hope that your comments have been addressed. Please note that all positive comments were removed from this response. The revised manuscript was marked with red colour.
Comment1: However, to shed light of the obtained results it is needed to add the key information about investigation sites: 1. Land-use history for the studied plots (the founded differences of some soil properties between plots could be related to different approach to land use in the past) 2. Current management practice for studied plots.
Response,
Thank you very much for your kindness comments. (1) The plantation of Eucalyptus grandis was built before the construction of P. zhennan plantation in this study site, and the P. zhennan plantation was conducted after felling. (2) Routine tending was carried out three years before afforestation, and there was no artificial interference in the later stage. We have supplied this information in the section of Experimental plot design and soil sampling. Please review line116-120.
Comment2: What is a main reason of changes soil pH, N, SOC between studied plots? It should be explained in discussion section.
Response,
We have supplied the contents about the reasons for changes in soil properties with stand density in the section of discussion. Please review line359-371.
Comment3: The results of statistical test should be clarified: in the Tables 2-4 given p-values, which were more than significance level, at the same time the different letters demonstrated significant differences between groups.
Response,
Multiple comparison was conducted after analysis of variance showed significant differences among groups. In this study, some indexes showed no significant difference among different plant density, such as pH, SBD, and SM, etc. Therefore, we revised the data analysis results in table 2, table 3, and table 4. And we also revised the related description in the text. Please review line242-243, 246-247, 262 and the revised table 2, 3, and 4.
Comment4: The conclusion should be formulated.
Response,
Thank you for your suggestion. We complemented the conclusion accordingly. Please review line444-458.
Comment5: It should be increased quality of figures – difficult to read.
Response,
We have uploaded images improving the resolution. Please review the revised figures.
Comment6: L.16-33 The abstract needs to re-write based on obtained results. It should be given more information regarding study sites and its feature. It should be given clear explanation of interface mechanism of plant density, soil properties and bacteria structure and diversity.
Response,
The abstract has now been rewritten. Please review line18-37.
Comment7: L.100 What is “S-sampling”?
Response,
“Five points sampling” method was used to sample the soil samples. One soil sample was taken from the four corners and the center of the plot, then five soil samples mixed into one composite sample. Please review line126-127.
Comment8: L.121-124 Give more details about soil analysis.
Response,
We have detailed the methods of soil analysis. Please review line153-161.
Comment9: L.198 As mentioned above in the table soil pH differed between groups (different letters). It should be clarified.
Response,
As your suggested that we have clarified the difference of soil pH among five stand densities in the section of results. Please review 242-244.
Comment10: L.329 The highest diversity of bacteria was under 700 stems/ha
Response,
We are very sorry for our negligence of this, and we have revised this sentence. Please review 388-389.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but marked in red in revised paper.
We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Reviewer 2 Report
I have revised the ms forests-2412462. This is very interesting manuscript aiming to provide a scientific reference for density management in P. zhennan plantations to enhance soil fertility maintenance techniques and ecological service functions. Congratulations to the authors.
Author Response
Dear reviewer,
Thank you for your kind letter and your careful work regarding our manuscript. We have revised the manuscript in accordance with your comments. And point-by-point responses to the comments were as follow.
Review2,
Comment1: I have revised the ms forests-2412462. This is very interesting manuscript aiming to provide a scientific reference for density management in P. zhennan plantations to enhance soil fertility maintenance techniques and ecological service functions. Congratulations to the authors.
Response,
We thank you for your approval. And we also revised the manuscript according to other reviewers’ suggestions, please review the revised manuscript.
Once again, thank you very much for your comments and suggestions.
Reviewer 3 Report
Review report on the manuscript n° Forests-2412462
Title :
The early effect of plant density on soil physicochemical properties, bacterial and understory plants diversity in Phoebe zhennan plantations.
Content of the manuscript
This study was conducted in 6-year Phoebe zhennan plantations, evaluating the effect of planting density on soil physicochemical properties, bacterial and understory plants diversity. The authors ultimately explored the links between the soil physicochemical attibutes and soil bacterial and understory plants diversity. The authors found that soil bacterial diversity decreased with increasing stand density. Bacterial diversity was found to be significantly influenced by soil pH, N-NH4+, N-NO3, Total P, and available P. No significant correlations between soil properties, understory vegetation, and bacterial diversity were found. The authors concluded that plantations with densities below 600 stems/hm2 were conducive to complex and stable soil bacterial communities.
As such, this work falls within the scope of journal Forests.
Reviewer’s main comments
The topic of the paper is interesting as it deals with the management of forest plantations based on the effects on soil microbial diversity and activities, which in turn drive nutrient cycling and soil carbon sequestration. The paper is really well presented and reads well. The experimental design is well described as well as the fields and laboratory protocols. Unfortunately, the manuscript suffers from many flaws raised below and that throw shade on the work.
Main flaws
1/ The paper does not add any significant or new information to the topic. The authors themselves stated at L 47-48 that‶ the variation in microbial composition under density control is well understood″. In L 51-52, they wrote ‶In Chinese fir plantations, high-density plantations decreased the composition and diversity of microbes″. The same trend was reported from other study in L 54-57. Further, in the Discussion section, L 321-323, the authors indicated again that "Multiple studies" have already shown that high densities cause a decline inmicrobial diversity. However, in the Introduction section, the authors missed/failed to hypothesize why the results would be different with Phoebe zhennan plantation…and at the end of their study, their results indicated the same trend !
2/ The authors didn't mesure soil moisture, which is strongly modulated by planting density and which in turn strongly influence soil biology. These data should have been included in the study.
3/ The results on SOC were not commented on in the abstract nor in the result section (L 197-206) despite the importance of SOC (energy source) in influencing soil biology.
4/ Throughout the manuscript, the authors should be clear, they should use the terms ‶soil physico-chemical attributes or characteristics″ instead of ‶soil properties″ because soil microbes diversity and functions are also part of the soil properties.
5/ All figures were blurry and most of the texts or legend included were not legible.
Other flaws
L 3 : ‶plant diversity‶ instead of ‶plants diversity″.
L 18 : Rather write "soil physico-chemical properties″
L 25-26 : you wrote : ‶The diversity of the soil bacteria decreased with increasing stand density″
This is not exact. Please be more clear: the density D5 demarcated from the other with a lower diversity of soil bacteria.
L 27 : NH4+-N instead of HN4+-N
L 40 : better write "diversity" instead of ‶variety″
L 97-98 : Please do not use abbreviation without having previously indicated the meaning in full.
L 102 : one composite sample
L 112 : Abbreviation of the Shannon-Wiener index is H', not H.
L 113 : Simpson index refers to as ‶D″ here, but in Table 2, it refers to as ‶C″. Please hormonize.
L 197 : Soil physicochemical properties : no comment on oxidizable SOC?
Table 3 : SOC and TN are lower in higher density stands than in lower density stands ? These results are a bit curious. Where are litter data? This could have helpled understand these results.
Table 4 : Why values of the Simpson index are the similar across tree densities? Are you sure this is correct ?
L 250 : levels (plural)
L 283-284 : I cannnot understand the meaning of this results. Why are you comparing compositions of different type of organisms? This seems meaningless.
L 311-312 : Unfortunately, your study does not add any clarification since you indicated in the Introduction section that the influence of planting density of the composition or diversity of soil microorganisms is well known (L 47-51).
L 316-317 : your wrote ‶This is caused by species specificity and the planting environment″. Please, lists some of these specificities…
L 321-323 : Here again, you are supporting that "Multiple studies" have already shown that high densities cause a decline in microbial diversity
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
Thank you for reviewing our manuscript and for the constructive comments, which greatly helped us to improve the manuscript. We have heavily revised our experiments. The manuscript was carefully revised and point-by-point response was listed below. We hope that your comments have been addressed. Please note that all positive comments were removed from this response. The revised manuscript was marked with red colour.
Reviewer’s main comments
Main flaws
Comment1: The paper does not add any significant or new information to the topic. The authors themselves stated at L 47-48 that‶ the variation in microbial composition under density control is well understood″. In L 51-52, they wrote ‶In Chinese fir plantations, high-density plantations decreased the composition and diversity of microbes″. The same trend was reported from other study in L 54-57. Further, in the Discussion section, L 321-323, the authors indicated again that "Multiple studies" have already shown that high densities cause a decline inmicrobial diversity. However, in the Introduction section, the authors missed/failed to hypothesize why the results would be different with Phoebe zhennan plantation…and at the end of their study, their results indicated the same trend !
Response,
Thank you for your careful work regarding our manuscript. The previous studies reported that the variety and composition of soil microbial communities vary considerably across temporal and geographical scales in terrestrial ecosystems, and they drive most biogeochemical processes and regulate soil nitrogen cycling. Nevertheless, the response of soil physicochemical attributes, understory vegetable, and soil microbes of plantation to density regulation is different with different tree species and tree age, the difference of optimal planting density is significant. Therefore, a deeper understanding is required to clarify how stand density affects the soil properties, understory vegetation, composition and diversity of soil microbes. The results could provide fundamental information for plantation management. However, no comprehensive analysis of the effects of stand density on soil physicochemical attributes, understory vegetation, and soil microbial, nor any detailed observations of correlations between biological and physicochemical properties have been performed in P. zhennan plantation. Therefore, we aimed to provide a scientific reference for density management in P. zhennan plantations to enhance soil fertility maintenance techniques and ecological service functions. We have supplemented this part in the section of introduction. Please review line52-54, 63-79, 94-100, 372-384, etc.
Comment2: The authors didn't mesure soil moisture, which is strongly modulated by planting density and which in turn strongly influence soil biology. These data should have been included in the study.
Response,
We are very sorry for our negligence of could not showed the method of soil moisture in the section of method. Now, we have supplemented the measure method and data of soil moisture in the text. And the results showed that there was no significant difference of soil moisture among five stand densities. Please review line150, table3, figure4B, figure5C, and figure6.
Comment3: The results on SOC were not commented on in the abstract nor in the result section (L 197-206) despite the importance of SOC (energy source) in influencing soil biology.
Response,
We have supplemented the results of SOC in the abstract and result section. Please review line22, 245-247.
Comment4: Throughout the manuscript, the authors should be clear, they should use the terms ‶soil physico-chemical attributes or characteristics″ instead of ‶soil properties″ because soil microbes diversity and functions are also part of the soil properties.
Response,
Thank you for your professional advice. It has been revised and completed in whole text. Please review line2-3, 18, 33, etc.
Comment5: All figures were blurry and most of the texts or legend included were not legible.
Response,
We have uploaded new figures improving the resolution. Please review the revised figures.
Other flaws
Comment6: L 3 : ‶plant diversity‶ instead of ‶plants diversity″.
Response,
It has been revised according to the comment. Please review line3-4.
Comment7: L 18 : Rather write "soil physico-chemical properties″
Response,
It has been revised according to the comment. Please review line18.
Comment8: L 25-26 : you wrote : ‶The diversity of the soil bacteria decreased with increasing stand density″. This is not exact. Please be more clear: the density D5 demarcated from the other with a lower diversity of soil bacteria.
Response,
This sentence has been revised as: The density D5 (850 stems/hm2) demarcated from the other with a lower diversity of soil bacteria. Please review line24-25.
Comment9: L 27 : NH4+-N instead of HN4+-N
Response,
We are very sorry for our negligence. It has been revised according to the comment. The mistyping errors in manuscript have been revised correspondingly. Please review line21, 30, 150, etc.
Comment10: L 40 : better write "diversity" instead of ‶variety″
Response,
It has been revised according to the comment. Please review line45.
Comment11: L 97-98 : Please do not use abbreviation without having previously indicated the meaning in full.
Response,
It has been revised according to the comment. Please review line121-123.
Comment12: L 102 : one composite sample
Response,
It has been revised according to the comment. Please review line127.
Comment13: L 112 : Abbreviation of the Shannon-Wiener index is H', not H.
Response,
It has been revised according to the comment. The mistyping errors in manuscript have been revised correspondingly. Please review line140, 231, 236, and table2, etc.
Comment:14 L 113 : Simpson index refers to as ‶D″ here, but in Table 2, it refers to as ‶C″. Please hormonize.
Response,
We have revised this mistake. Please review line140, 229, and table2.
Comment15: L 197 : Soil physicochemical properties : no comment on oxidizable SOC?
Response,
We have revised the comments on SOC. Please review line244.
Comment16: Table 3 : SOC and TN are lower in higher density stands than in lower density stands ? These results are a bit curious. Where are litter data? This could have helpled understand these results.
Response,
We checked the data, the SOC and TN are lower in higher density stand than in lower density stands. Plants in higher densities need to use and uptake greater amounts of nutrients (Will et al, 2005). Therefore, the contents of TN and SOC in the relatively high-density plantations were lower than those in the relatively low-density plantations of P. zhennan. We discussed and explained this situation in the section of discussion. Please review line361-364.
Comment17: Table 4 : Why values of the Simpson index are the similar across tree densities? Are you sure this is correct ?
Response,
We checked the data, and sure that the Simpson index are the similar across tree densities. The Simpson index of all 15 samples ranged from 0.9898 to 0.9938. There is no obvious difference of diversity among the five stand densities which the diversity is referred by Simpson index.
Comment18: L 250 : levels (plural)
Response,
It has been revised according to the comment. Please review line295.
Comment19: L 283-284 : I cannnot understand the meaning of this results. Why are you comparing compositions of different type of organisms? This seems meaningless.
Response,
The results were used to analyze and explain the correlation between the soil physico-chemical attributes and the composition of soil bacterial, herbs, and shrubs under density control. The redundancy analysis (RDA) results revealed that there were closed relationship between the soil physico-chemical attributes and the compositions of soil bacterial, herbs, and shrubs under density control. Please review line330-332.
Comment20: L 311-312 : Unfortunately, your study does not add any clarification since you indicated in the Introduction section that the influence of planting density of the composition or diversity of soil microorganisms is well known (L 47-51).
Response,
Considering the Reviewer’s suggestion, we have deleted this sentence.
Comment21: L 316-317 : your wrote ‶This is caused by species specificity and the planting environment″. Please, lists some of these specificities…
Response,
As Reviewer suggested that we have listed species specificity and the planting environment effected the dominance soil bacterial. Please review line376-380.
Comment22: L 321-323 : Here again, you are supporting that "Multiple studies" have already shown that high densities cause a decline in microbial diversity
Response,
Considering the Reviewer’s suggestion, we have deleted this sentence.
Comment23: Other suggestion marked in the pdf attachment.
Response,
All suggested revisions which pointed in the pdf attachment were accepted and the manuscript has been revised accordingly.
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we did not list the changes but marked in red in revised paper.
We appreciate for your warm work earnestly, and hope that the correction will meet with approval.
Round 2
Reviewer 1 Report
The authors have answered on all comments carefully and improved the manuscript quality.
Reviewer 3 Report
After a checking of my initial review report on this manuscript, I can confirm that my decision was to reject it. This decision was based on serious flaws that enable publication of this article. Therefore, I cannot review the revised version because I've doubt about the sincerity of the modifications.
