Short-Term Effects of Tunnel Construction on Soil Organic Carbon and Enzyme Activity in Shrublands in Eastern Tibet Plateau
Shamsollah Ayoubi
Round 1
Reviewer 1 Report
The work presented in this manuscript is about the evaluation of changes in SOC, and enzyme activities after the construction of a tunnel in East Tibetain plateau. The manuscript describes the situation in the soils of two vegetation types, a few months after the onset of the construction project. The presentation is clear, sound although some improvement in the style might be needed (comments were left on the manuscript). The project is coherent by itself but my concern is about its conception. I mean you sampled eight/nine months after the start and just at the end of the rainy season. This could not show any differences between treatments (locations) as this is too soon to conclude. Not surprising that you quote many publications that found the contrary.
1. The main question was : Does tunnel construction cause any changes in the soil organic carbon and enzyme activities?
2. The topic is relevant and addresses a gap in the field, as the authors wrote, tunnels are widely constructed in more or less fragile ecosystems.
3. The authors idea was to compare between sites above the tunnel and 'undisturbed sites' from the vicinity used as controls. So far, so good. But the work was biased in my opinion. Samples were taken too shortly after the start of the construction, at a time when soils were still moist. For this, the work demonstrated no negative effects of tunnel construction. These results are expectable and that is my source of concern. It seems that the initial idea was to demonstrate the innocuity of tunnel construction rather than observe and measure in a fully objective way. The comments to improve the manuscript are already included. Minor changes will be sufficient but the fundamental question (raised in 3) remains to be answered. Can a work conducted 8 months after the start of the work and at the end of the rain season reflect the changes caused by a major construction project?? One of the issues could be to insist on the short-term effect of this study In brief, the work as written, analyzed is relatively sound but the underlying approach is biased in my opinion.
Comments for author File: 
Comments.pdf
Author Response
Comments from the editors and reviewers:
-Reviewer 1
The work presented in this manuscript is about the evaluation of changes in SOC, and enzyme activities after the construction of a tunnel in East Tibetan plateau. The manuscript describes the situation in the soils of two vegetation types, a few months after the onset of the construction project. The presentation is clear, sound although some improvement in the style might be needed (comments were left on the manuscript). The project is coherent by itself but my concern is about its conception. I mean you sampled eight/nine months after the start and just at the end of the rainy season. This could not show any differences between treatments (locations) as this is too soon to conclude. Not surprising that you quote many publications that found the contrary.
- The main question was: Does tunnel construction cause any changes in the soil organic carbon and enzyme activities?
Response: thank you very much for insightful comments. We fully agree with you that few months after the tunnel construction may not affect SOC and its components, which could be a limitation of our study.
On the other hand, we also aimed to detect the short-term effects of tunnel construction on SOC components and microbial activities, which might be sensitive to environmental changes even in a short-term because there was a large amount of belowground water loss up to 50000 m3 per day after tunnel construction. However, our result could not support our hypothesis that the short-term effects of tunnel construction did not affect SOC and soil enzymes. As suggested, we addressed this limitation in the revised manuscript and proposed our hypothesis.
- The topic is relevant and addresses a gap in the field, as the authors wrote, tunnels are widely constructed in more or less fragile ecosystems.
Response: thank you very much for your encourage. According to your useful comments and suggestion, we revised our manuscript carefully with a point-to-point response below.
The author idea was to compare between sites above the tunnel and 'undisturbed sites' from the vicinity used as controls. So far, so good. But the work was biased in my opinion. Samples were taken too shortly after the start of the construction, at a time when soils were still moist. For this, the work demonstrated no negative effects of tunnel construction. These results are expectable and that is my source of concern. It seems that the initial idea was to demonstrate the innocuity of tunnel construction rather than observe and measure in a fully objective way. The comments to improve the manuscript are already included. Minor changes will be sufficient but the fundamental question (raised in 3) remains to be answered. Can a work conducted 8 months after the start of the work and at the end of the rain season reflect the changes caused by a major construction project?? One of the issues could be to insist on the short-term effect of this study in brief, the work as written, analyzed is relatively sound but the underlying approach is biased in my opinion.
Response: thank you again. Since previous studies have never proved the influence of tunnel construction on SOC and enzyme activities and we hypothesized that tunnel construction may affect SOC and soil enzymes because more than 50000 m3 belowground water loss per day and we aimed to detect the short-term effects of tunnel construction on SOC and soil enzymes. However, as mentioned above, our result could not support our hypothesis that short-term effects of tunnel construction did not affect SOC and soil enzymes. We addressed this limitation and hypothesis in revised manuscript. Furthermore, we revised our research objectives and proposed a hypothesis:
“Therefore, the short-term effects of tunnel construction on SOC and its fractions and soil enzyme activities were examined in this study. Since SOC fractions and soil enzymes are very sensitive to environmental change (Ghani et al., 2003; Haynes, 2005; Trasar-Cepeda et al., 2008), it is hypothesized that tunnel construction had a significant impact on SOC and soil enzyme because up to more than 50000 m3 belowground water loss per day during the tunnel construction.”
We further proposed that a long-term monitoring process is required and we are doing so in the field.
Please see more details on the point-to-point changes below.
- Title
Response: changed to title to: “Short-term effects of tunnel construction on soil organic carbon and enzyme activities in shrublands in Eastern Tibet Plateau”.
- Abstract: L21: we, L36: our; L37: our
Response: done as suggested through the text.
- Introduction
L70: removed “a”
L72: removed “changing”
L88-89: removed “soil organic matter and decomposed
L117: removed “we”
Response: done as suggested.
- Materials and methods
L136: Please provide more information: was the work still going on?
Response: thank you for your suggestion and comments. The construction period will last about 10 years, and the project is continuing. We have added relevant information in the manuscript.
What is the depth of excavation?
Response: the depth of the tunnel is about 80m and we added this information in the manuscript.
Any visual disturbance to the selected sites?
Response: no visual disturbance was observed before tunnel construction from personal interview of local residence and remote sensing images.
Experimental design and soil sampling: L148: we, L157: we, L158: we, L163: We
Response: we corrected this unscientific expression.
L165: Please explain how the sampling was conducted: using the 100 cm x 100 cm quadrat was the vegetation entirely removed for biomass evaluation???
Response: sorry for the unclear statement. A 100 cm x 100 cm subplot was set at directs of 0°, 120° and 240° for vegetation and soil sampling. We added this information in the text.
L190: SOC determined could this be the same as Walkley-Black method consisting of an attack by a mixture of dichromate/concentrated sulfuric acid at room temperature?
Response: The method used in this study is different from Walkley-Black method consisting of an attack by a mixture of dichromate/concentrated sulfuric acid at room temperature because air-dried soil consisting of an attack of a mixture of potassium dichromate/concentrated sulfuric acid at 170-180 ℃ for 5 min.
L242: Please explain this: the control was the plots occupied by native vegetation without disturbance. Right?
Response: Yes, the control site has similar soil and vegetation characteristics with tunnel affect plot. This information was added in the text
- Statistical analysis: L226: we; L163: removed “we”
Response: done as suggested.
- Results
L243: removed “we”
Response: done as suggested.
L247-253: Rewrite this please
Response: thank you for your suggestion and comments.
“The soil cellulase content of TA1 was 0.31 ± 0.18 mg g-1 24h-1, which was significantly lower than that of CK1 (0.70 ± 0.40 mg g-1 24h-1, p < 0.001, Fig 4B). However, sucrase, polyphenol and catalase contents of Q. aquifolioides shrubland were 14.82 mg g-1 24h-1, 0.06 mg g-1 24h-1, 0.62 mg g-1 24h-1, which significantly lower than those of mixed shrublands (48.82 mg g-1 24h-1, 0.18 mg g-1 24h-1,1.09 mg g-1 24h-1, Fig 4).”
L281: Better to split this into two figures: separate the enzymes from the SOC and its fractions.
Response: done as suggested.
L259: Figure 3
L264: Figure 4
L275: table 3 instead of 5
Response: done.
- Discussion
L287: Our; L297, L316, L319, L330, L338, L353, L355: our; L299, L307, L343: We,
Response: done.
L300-303: This result may be associated short-term effect of tunnel construction because the tunnel construction in December 2020, which might lead to a minor impact on soil moisture and vegetation growth.
Sure, Good conclusion
Response: we are very sorry for the short period of our study and long-term monitoring of the area has been ongoing. We further proposed that a long-term monitoring process is required and we are doing so in the field.
L359-361: Thus, the soil enzyme of adhere to SOC and its fractions can form humus-protein complexes that can protect enzymes from decomposition (Ma et al., 2020). Rewrite, please
Response: done as below:
“Ma et al., (2020) showed that soil enzymes adhere to organic carbon and its fractions to form humus-protein complexes, which protects soil enzymes from decomposition.”
L366: There was a significant difference in cellulase between TA1 and CK1, and compared with CK1, TA1 decreased by 55.32% in our study (Fig. 3B). Rewrite this sentence please.
Response: thanks again for your advice. “The cellulase content of TA1 was 55.32% lower than that of CK1”
L377-379: At present, we have not yet discovered the reason for the change of cellulase in the affected area of the tunnel.
Response: we have revised this sentence as below:
“At present, the cause of cellulase change in the affected area of the tunnel remains unclear due to the short time of tunnel construction.”
- Conclusions
Response: Our => The ; “we conducted our study” => “the study was conducted”
Reviewer 2 Report
Please see the attachment
Comments for author File: Comments.pdf
Author Response
Comments from the editors and reviewers:
-Reviewer 2
- Title
Looks like a sentence not title, Need correct title as “Effect of ………… on SOM and enzyme activities of shrub lands in Eastern Tibet Plateau”.
Made the title self-explanatory and reflect the research work.
Response: we changed the title to: “Short-term effects of tunnel construction on soil organic carbon and enzyme activities in shrublands in Eastern Tibet Plateau”.
- Abstract
Many non-scientific word should be removed such as “our, we” and improve the sentences in scientific writing method.
Response: we are deeply sorry for the non - scientific word, We have deeply reviewed such problems in this manuscript and made some modifications.
Abstract: L21: we, L36: our; L37: our
Response: done as suggested through the text.
Line 18 “affected” should be removed and add “on”.
Response: done as suggested
Correct grammatical mistakes
Response: we apologize for the poor language of our manuscript. In the revised manuscript, we revised the language carefully again throughout the text. We hope the language issues would not affect your review.
- Introduction
Check for commas and full stops where needed as line 58.
Response: it is full stop.
Some sentences are incomplete as line 68 “thus regulation SOC”????
Response: we mean SOC contents, and corrected.
Rove bracket (Kivlin and Treseder, 2013) with the name in line 89.
Response: done.
Correct spelling mistakes on line 93.
Response: done.
Need grammatical correction to line 106 – 107.
Response: done.
- Materials and methods
The site is not explained for variables in legend as TA1 CK1 and 2 stand for???
Response: sorry for the confusion. TA1: tunnel-affected areas 1, CK1: non-tunnel-affected areas 1, TA2: tunnel-affected areas 2, CK2: non-tunnel-affected areas 2.
AGA (is it microbial biomass) if so label it rightly on the legend.
Response: AGB stands for aboveground plant biomass and is annotated in the legend of Table 1.
Rive bracket from reference line 68 and only add to the year as Vance et al. (1987).
Response: done.
Line 178 the method for labile method is not clear.
Response: sorry for the unclear statement. We have added more details about the method to determine SOC fractions
- Results
Correct the spelling and other variable in the legend of tables and figures.
Response: thank you for your suggestion and comments. We have divided Figure 3 into two figures: the separation of enzymes from SOC and its components, and correct the spelling and other variable in the legend of tables and figures.
TA1: tunnel-affected areas 1, CK1: non-tunnel-affected areas 1, TA2: tunnel-affected areas 2, CK2: non-tunnel-affected areas 2.
SC: sucrase, CL: cellulase, PPO: polyphenol, and CAT: catalase, SWC: soil water content, AGB: aboveground biomass.
Figure three is confusing and as mention the value of SOC < DOC are higher in mixed shrub land than other (Table 3) but not shown in the figure where is shrub land and other vegetation.
Response: sorry for the confusion. The mixed shrubland was represented TA2 and CK2, which were mixed with Quercus aquifolioides, Rhododendron phaeochrysum and Betula platyphylla. The results of two-way analysis were shown in Table 2 with p = 0.009.
- Discussion
Reduce repetition of similar words, use alternative words.
Response: done.
Need correction of grammar and language.
Response: we revised the language carefully with my colleagues. We acknowledge their help in the acknowledgement.
No single literature supports the finding, looks even author is not confident on the results.
Response: thank you again. Since previous studies have never proved the influence of tunnel construction on SOC and enzyme activities and we hypothesized that tunnel construction may affect SOC and soil enzymes because about 50000 m3 belowground water loss per day and we aimed to detect the short-term effects of tunnel construction on SOC and soil enzymes, however, our result could not support our hypothesis that short-term effects of tunnel construction did not affect SOC and soil enzymes. We addressed this limitation and hypothesis in revised manuscript. We further proposed that a long-term monitoring process is required and we are doing so in the field.
Line 261 the “data” from weather station not mentioned in the results
Response: according to the meteorological information in the environmental risk identification report of this project, we know that the average annual sunshine duration in this research area is 1689.9 h. Therefore, we have corrected our data information.
MBC is significantly affected in present study which will affect the enzymes but you don’t support it in your results and discussion both.
Response: thank you for insightful comments. Because we did not measure root biomass and other functional traits, we could not provide results about root. However, according to previous studies, root biomass would be an important factor affecting MBC, therefore, we cite several related references to demonstrate the changes of MBC.
Remove bracket from ref in 309 line and add only to the year.
Response: done.
Line 315 mentioned table 5 (absent in the results).
Response: done.
L397: Table 3
Correct references, 363- 365 and 389 -391
Response: done.
References
Blair, G.J., Lefroy, R.D.B. and Lisle, L., 1995. Soil Carbon Fractions Based on their Degree of Oxidation, and the Development of a Carbon Management Index for Agricultural Systems. Aust. J. Agric. Res., 46: 1459-66.
Reviewer 3 Report
Sustainability 2022, 14, x. https://doi.org/10.3390/xxxxx www.mdpi.com/journal/sustainability Essay 1 The paper on Tunnel construction had minor effects on soil organic carbon and enzyme activities in shrublands in Eastern Tibet Plateau. Written result and discussion. But some suggestions from my side , in Abstract data should be given in quantification form.
Material methods please give brief about DOC and EOC methodology
Discussion some more relevant support reference can be added. .. Conclusion can be only significant findings should be given. Also cross check all reference and journal format
Author Response
Comments from the editors and reviewers:
-Reviewer 3
Written result and discussion. But some suggestions from my side, in Abstract data should be given in quantification form.
Response: thank you for your suggestion and comments. According to the reviewers, we have revised the abstract of the manuscript:
L24-28: “regardless of vegetation type, SOC, dissolved organic carbon, easily oxidizable carbon were 27.14 ± 2.87, 6.70 ± 0.74 and 0.29 ± 0.10 g kg-1 for tunnel affected area with Q. aquifolioides and 47.96 ± 17.89, 11.19 ± 2.92 and 0.24 ± 0.04 g kg-1 for the mixture of Q. aquifolioides, R. phaeochrysum and B. platyphylla, respectively” was added.
L30, L33: “(p > 0.05)” was added.
Material methods please give brief about DOC and EOC methodology.
Response: thank you. We added related methods to DOC and EOC. .
Discussion some more relevant support reference can be added. Conclusion can be only significant findings should be given. Also cross check all reference and journal format
Response: thank you. We added more references in discussion section to support our study. The conclusion was shortened and the reference format was reformatted.
Reviewer 4 Report
Dear Editor in Chief of Sustainability
As the reviewer of the manuscript entitled as ‘Tunnel construction had minor effects on soil organic carbon and enzyme activities in shrublands in Eastern Tibet Plateau ” I went through the manuscript and found that it has merits to publish in an international Journal and it is line with Scope of your Journal. But It suffers from minor shortcomings, that I highlighted on the attached file. In overall, I am suggesting minor revisions before publications
Sincerely Yours .
Comments for author File: Comments.pdf
Author Response
Comments from the editors and reviewers:
-Reviewer 4
- Title
change to more attractive title.
Response: thank you. We changed the title to “Short-term effects of tunnel construction on soil organic carbon and enzyme activities in shrublands in Eastern Tibet Plateau”.
L32-33: provide some quantitative information of your results here.
Response: thank you for your suggestion and comments. According to the reviewers, we have revised the abstract of the manuscript:
L24-28: “Results showed that regardless of vegetation type, SOC, dissolved organic carbon, easily oxidizable carbon were 20.57 - 67.89 g kg-1, 0.21 – 0.40 g kg-1, 5.30 – 13.98 g kg-1… for tunnel affected area with Q. aquifolioides and the mixture of Q. aquifolioides, R. phaeochrysum and B. platyphylla, respectively, which were not significantly different from those of tunnel unaffected areas (p > 0.05).” was added.
L30, L33: “(p > 0.05)” was added.
L57-60: see and cite to:
Garosi, Y., et al., 2022. Effects of different sources and spatial resolutions of environmental covariates on predicting soil organic carbon using machine learning in a semi-arid region of lran. Geoderma Regional. e00513.
Zeraatpisheh, M., et al., 2021. Spatial prediction of soil aggregate stability and soil organic carbon in aggregate fractions using machine learning algorithms and environmental variables. Geoderma Regional.
Response: thank you. The two references were cited.
L129: geographical location? Latitude elevation
Response: we are very sorry that we cannot provide the specific location coordinates of the study area in the manuscript. According to the requirements of relevant departments and privacy policies, some sensitive information involved in this project needs to be avoided. Please understand.
L144-146: not necessity, pleased remove it.
Response: we agreed with the reviewer’s comment and remove Figure 2.
L181: Table 1. Soil physical-chemical properties and aboveground biomass of four study sites. How many samples? N=????
Response: we are deeply sorry for the unclear legend. First of all, we set up two sample sites in the tunnel influence zone (TA1 and TA2) and two groups of parallel sites in the non-impact zone (CK1 and CK2), a total of 4 sample sites, and repeated sampling has been carried out for three times in each sample site.
L167: “(n = 3)” was added.
L168: “values represent mean and standard error, n=3.” was added.
L250: which design?
Response: we are deeply sorry for the unclear design method. Since we selected two different vegetation types in the tunnel affected area and the non-tunnel affected area, we use two-way analysis of variance analyses to explore the influences of tunnel construction and vegetation types on soil organic carbon and enzyme activities and whether their interaction is significant.
L281: Fig 3 use letters on the bars for comparison.
Response: we conducted two-way analysis of variance, therefore, we list p value in Table 2and did not used the letter on the bars.
L302-303: Table 3. Correlation coefficient between soil organic carbon and soil enzyme activity and environ mental factors. Numbers or sample are essential.
Response: we are deeply sorry for the unclear legend. We have corrected the legend.
L261: “(n = 12)” was added.
L310-311: Our study found that tunnel construction had no significant effect SOC content (Table 2). What level of significance?
Response: thank you for your careful revision.
L269: “p = 0.796”
We found that EOC and DOC were significantly positively correlated with SWC and AGB (Table 3), while SWC and AGB in the tunnel affected area were not significantly different from those in the non-tunnel affected area (Table 1). How much correlation? it was significant? What level?
Response: we are very sorry for the lack of clarity. The correlation of EOC, DOC and SWC, AGB all showed ** (Table 3), indicating that the correlation level reached 0.01.
L288: “r = 0.71 – 0.85” was added.
L366-368: We found that there were no significant differences in sucrase, polyphenol and catalase at tunnel-influenced and non-tunnel-influenced, indicating that tunnel excavation had no effect on soil enzyme activities. Identify the level of significance.
Response: L367: “(p > 0.05, Table 2)”
Round 2
Reviewer 1 Report
Good effort.
Author Response
Dear reviewers and editors,
Greetings!
First of all, thank you very much for taking time out of your busy schedule to read and revise my article. Thank you for your valuable advice. You have made a comprehensive correction to the structure, content, research methods and results of my paper. It has played a very important role in improving the quality of my thesis.
Reviewer Comments: The revised version of the manuscript is fine. It
emphasizes the short-term effect. Some minor modifications need to be introduced to the text, e.g. in the materials and methods the authors wrote that 'within each direct' what they meant 'within each direction'
Response: sorry for the unclear statement. In the materials and methods, "within each direct" means " within each direction".
I have carefully studied the reviewer's comments and made careful modifications to the paper according to the suggestions, as follows:
1. Abstracts are refined to make the language more refined
2. Further checked the references, and further refined and concentrated the paper
Please see attached for more details
Author Response File: 
Author Response.docx
