Study on the Root Characteristics and Effects on Soil Reinforcement of Slope-Protection Vegetation in the Chinese Loess Plateau

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Re: Reviewer’s comments on “Study on the Root Characteristics and Soil Stabilizing Capacity of Slope Protection Vegetation in the Chinese Loess Plateau.”

 

I.          Abstract: Excellent.

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II.         Introduction:

            Lines 34-42. I would recommend that whenever a semi-colon is used, replace it with a period and start a new sentence with the next word.

            Line 34. I would recommend this wording change: “…climate-heavy rain that…” Climate isn’t a proper word, so it should be all lower case.

            Line 35. Consider changing “rock types” to “soil geology.”

            Line 40. The new sentence would start as “Surface vegetation can effectively…[5,6].

            Line 55. “…generate a large amount of debris…”

            Line 67. Suggest “…such as the plant and soil sciences.” Then, omit the rest of the sentence since the following sentences make it redundant.

            Line 69. Suggest “For instance…plant root systems…”

            Line 71. Suggest “…massive root systems…”

            Line 96. I would recommend that this sentence become the first sentence of a new paragraph.      

            Line 111. “…soil conservation by tree species…”

            Line 113. Stop the sentence after “...efficiency.” This avoids redundancy.

           

            The Introduction is complete and ends with a good research statement.

 

III.       Materials and Methods.

            Very good background to begin this section.

            Line 182. Use a period to end the sentence after “…calculated.”

            Lines 197-202. Grammar-wise, this long and complicated sentence would benefit by creating two separate sentences, to wit:

                        “The average diameter (d) of a root’s length was calculated by taking the average of three points along the upper, middle, and lower sections of an excavated root. The root systems of the sampled trees were subsequently classified into four class sizes: fine roots…(d10mm).

            Line 218. “…were counted..”

            Lines 233-235. Recommend removing parentheses at the beginning and end of the noted tree species.

 

            Very complete materials and methods section. Statistical analysis was appropriate. Selection and evaluation of the subject trees and shrubs was very complete, appropriate, and defensible.

           

IV.        Results.

            Line 259. “…species varied from…” You should use past tense verb forms since the study has concluded and you are only referencing the sampled trees.

            Line 260. “…was the largest,…”

            Line 261. “…varied…”

            Line 263. “…which was…”

            Line 265. “…had relatively…”

            Line 268. “…species ranged…”

            Line 269. “…had…”

            Line 271. “…had…”

            Line 272. “…had…”

            Line 274. “…relied…”

            Line 275. “…had significantly…”

            Line 276. “...relied…”

            Line 280. “…first order…” not firstorder.

 

The results section was very good. All tables and figures were completely explained and logical to read.

 

V. Discussion.

            Line 412. Would “stabilize” be a better descriptive word than “compact?”

            Line 466. I would suggest this be the beginning of a new paragraph since the topic has now shifted to a discussion of root angle. Plus, the existing paragraph is very long and by breaking it into two logical paragraphs, it makes it much more readable.

            Line 488. “…focused…” since the study has concluded.

 

Very good discussion section. Comments and suppositions were supported by evidence, either from this study or previous studies by other authors.

 

VI. Conclusion.

            Succinct and a very good summary of the study and implications for stabilizing loess soils.

Comments on the Quality of English Language

See previously comments to the authors.

Author Response

1. Abstract: Excellent.

A: thank you very much.

2. Lines 34-42. I would recommend that whenever a semi-colon is used, replace it with a period and start a new sentence with the next word.

A: we had revised them according to the comments.

3. Line 34. I would recommend this wording change: “…climate-heavy rain that…” Climate isn’t a proper word, so it should be all lower case.

A: we had revised the word.

4. Line 35. Consider changing “rock types” to “soil geology.”

A: we had replaced “rock types” to “soil geology.”

5. Line 40. The new sentence would start as “Surface vegetation can effectively…[5,6].

A: we had revised the sentence.

6. Line 55. “…generate a large amount of debris…”

A: we had revised the word.

7. Line 67. Suggest “…such as the plant and soil sciences.” Then, omit the rest of the sentence since the following sentences make it redundant.

A: we had revised the sentences according to the comments.

8. Line 69. Suggest “For instance…plant root systems…”

A: we had revised the sentence.

9. Line 71. Suggest “…massive root systems…”

A: we had revised the sentence.

10. Line 96. I would recommend that this sentence become the first sentence of a new paragraph.      

A: we had revised them.

11. Line 111. “…soil conservation by tree species…”

A: we had revised the sentence.

12. Line 113. Stop the sentence after “...efficiency.” This avoids redundancy.

A: we had revised the sentence.

13. The Introduction is complete and ends with a good research statement.

A: Thank you.

14. Line 182. Use a period to end the sentence after “…calculated.”

A: we had revised it.

15. Lines 197-202. Grammar-wise, this long and complicated sentence would benefit by creating two separate sentences, to wit:

A: we had revised the sentences.

16. Line 218. “…were counted..”

A: we had revised the word.

17. Lines 233-235. Recommend removing parentheses at the beginning and end of the noted tree species.

A: we had removed the parentheses.

18. Very complete materials and methods section. Statistical analysis was appropriate. Selection and evaluation of the subject trees and shrubs was very complete, appropriate, and defensible.

A: Thank you.

19. Line 259. “…species varied from…” You should use past tense verb forms since the study has concluded and you are only referencing the sampled trees.

A: we had revised the word.

20. Line 260. “…was the largest,…”Line 261. “…varied…”Line 263. “…which was…” Line 265. “…had relatively…”Line 268. “…species ranged…”Line 269. “…had…”Line 271. “…had…” Line 272. “…had…”Line 274. “…relied…”Line 275. “…had significantly…”Line 276. “...relied…”Line 280. “…first order…” not firstorder.

A: we had revised above issues.

21. Line 412. Would “stabilize” be a better descriptive word than “compact?”

A: we had replaced the word.

22. Line 466. I would suggest this be the beginning of a new paragraph since the topic has now shifted to a discussion of root angle. Plus, the existing paragraph is very long and by breaking it into two logical paragraphs, it makes it much more readable.

A: we had break it into two paragraphs.

23. Line 488. “…focused…” since the study has concluded.

A: we had revised the word.

24. Succinct and a very good summary of the study and implications for stabilizing loess soils.

A: Thanks for your comments.

Reviewer 2 Report

Comments and Suggestions for Authors

Several questions and remarks regarding the paper by Zhang et al. “Study on the root characteristics and soil stabilizing capacity of slope protection vegetation in the Chinese Loess Plateau”.

 

Please define explicitly the aim and tasks of your study.

Specify when you conducted your study. Month (or months) and year (or years).

Despite the title of the manuscript indicating that the "soil stabilising capacity" (“Study ... and soil stabilizing capacity...”) will be studied, the text lacks any soil-stability analysis. Please provide these data.

“The curve of pull-out force versus displacement was plotted…” (Lines 229-230). This is one of the key results of your study. Please provide these results.

To comprehend the conditions under which roots grow and how they affect the "soil stabilising capacity", there is not enough data available to characterise the soil of the test locations. Data on soil cohesion and texture should be provided. Furthermore, you must consider the fact that soil properties change with depth. Please provide a thorough examination of how root systems affect the "soil stabilising capacity" while accounting for depth-related changes in soil properties.

“Slope protection vegetation in the basin includes the shrubs … and the trees …” (Lines 142-143). Does this description imply that the research was conducted on the slopes? However, no characteristics of the slopes are presented! Slope aspect? Slope gradient? Please provide these data.

How did you measure (calculate) DBH of shrub species (Lines 181-182)? Diameter at breast height (DBH) is measured at approximately 1.3 m above ground. The shrub (Caragana korshinski) within your test plots has a height of only 1.8 m.

Table 1. Ground diameter? Do you mean the "stem (trunk) diameter" parameter?

The authors must correctly specify the Latin names of the plants. First, you must provide an accepted biological name, not synonyms: Armeniaca sibirica (L.) Lam. - this name is a homotypic synonym of Prunus sibirica L. (accepted Latin name). Second, the first mention of the species' Latin name in the text should be given in full.

Four tree species and two shrub species were the subjects of this study. However, all the table and figure titles state that only different woody plant species were examined (…sample trees…, …different tree species…, …various tree species…). All of the figure and table captions need to be corrected, and it should be stated that "species of shrubs and trees" were examined.

Figures 2-4. The legends for each figure need to be updated. As mentioned in the Method section (Lines 201-202), the names of the root fractions must be given. Fine, small, medium, etc.

Figure 1 has a very low quality. It presents extremely difficult-to-read information. Kindly supply a figure of greater quality.

Paragraphs between lines 148 and 176. First, the electronic links take readers to the Chinese Wikipedia header page. Second, citing Wikipedia in scholarly publications is strongly discouraged. I am sure that many scientists have researched the plant species chosen as the subject of this research. Finding references to these studies will not be a problem.

Add research limitations to the Discussion section.

Author Response

1. Please define explicitly the aim and tasks of your study.

A: we had revised the last paragraph of the introduction as follow:

Although ecological construction work such as soil conservation by tree species has been carried out to protect soil resources and ensure food production, the basic theoretical research on root function of water and soil conservation tree species is still relatively weak, which seriously affects the full play of the vegetation function efficiency. Therefore, this study focuses on six main woody plant species commonly used for water and soil conservation on the Loess Plateau, including Caragana korshinskii, Hippophae rhamnoides, Pinus tabuliformis, Robinia Pseudoacacia, Populus tomentosa, and Armeniaca sibirica. The aims of this study are (1) quantifying the differences of root configuration characteristics of different soil and water conservation plants. (2) evaluating soil retaining ability of the whole root system of different plants, and determining the relationship between the soil retaining ability of the whole root system and root configuration. The research results can provide a scientific basis for the selection of tree species in water and soil conservation vegetation construction on the Loess Plateau.

2. Specify when you conducted your study. Month (or months) and year (or years).

A: we had revise the first sentence of study area as follow:

Fieldwork was performed from 3^rd August to 26^th September, 2022 in Chengguohe River Basin, a secondary tributary of the Zuli River in the Yellow River Basin, with a total area of 161.37 km².

3. Despite the title of the manuscript indicating that the "soil stabilising capacity" (“Study ... and soil stabilizing capacity...”) will be studied, the text lacks any soil-stability analysis. Please provide these data.

A: I'm sorry to confuse you. It is true that there is no relevant content about soil stability in this paper. This study only studied the soil reinforcement ability of roots of different vegetation types. The title was revised to “Study on the Root Characteristics and the effects on soil reinforcement of Slope Protection Vegetation in the Chinese Loess Plateau”.

4. “The curve of pull-out force versus displacement was plotted…” (Lines 229-230). This is one of the key results of your study. Please provide these results.

A: we had added the curve of pull-out force versus displacement as follow:

From the process of pulling force and root displacement, The root displacement of the maximum pulling force of C. korshinskii, H. rhamnoides, P. tabuliformis, R. pseudoacacia, P. tomentosa and P. armeniaca appeared at 11 cm, 6 cm, 15 cm, 8 cm, 15 cm and 5 cm, respectively (Figure 7).

      

Figure 7. The curves of pull-out force versus displacement of different species of shrubs and trees.

5. To comprehend the conditions under which roots grow and how they affect the "soil stabilising capacity", there is not enough data available to characterise the soil of the test locations. Data on soil cohesion and texture should be provided. Furthermore, you must consider the fact that soil properties change with depth. Please provide a thorough examination of how root systems affect the "soil stabilising capacity" while accounting for depth-related changes in soil properties.

A: This study focused on the soil reinforcement ability of vegetation roots, and did not involve the content of soil stability. At the same time, the properties of the soil were determined during the experiment. The relevant information has been added to Table 1.

6. “Slope protection vegetation in the basin includes the shrubs … and the trees …” (Lines 142-143). Does this description imply that the research was conducted on the slopes? However, no characteristics of the slopes are presented! Slope aspect?Slope gradient? Please provide these data.

A: The test was carried out on a slope. The detailed information is supplemented in Table 1.

7. How did you measure (calculate) DBH of shrub species (Lines 181-182)? Diameter at breast height (DBH) is measured at approximately 1.3 m above ground. The shrub (Caragana korshinski) within your test plots has a height of only 1.8 m.

A: We have explained this problem in Table 1. For shrubs we use the concept of base diameters (BD). For trees we use the concept of DBH. DBH is the diameter at breast height for trees, DB is the basic diameter for shrubs.

8. Table 1. Ground diameter? Do you mean the "stem (trunk) diameter" parameter?

A: We had revised the problem. For shrubs we use the concept of base diameters (BD). For trees we use the concept of DBH. DBH is the diameter at breast height for trees, DB is the basic diameter for shrubs.

9. The authors must correctly specify the Latin names of the plants. First, you must provide an accepted biological name, not synonyms: Armeniaca sibirica (L.) Lam. - this name is a homotypic synonym of Prunus sibirica L. (accepted Latin name). Second, the first mention of the species' Latin name in the text should be given in full.

A: we had revised the Latin name in the manuscript.

10. Four tree species and two shrub species were the subjects of this study. However, all the table and figure titles state that only different woody plant species were examined (…sample trees…, …different tree species…, …various tree species…). All of the figure and table captions need to be corrected, and it should be stated that "species of shrubs and trees" were examined.

A: we had revised all table and figure titles.

11. Figures 2-4. The legends for each figure need to be updated. As mentioned in the Method section (Lines 201-202), the names of the root fractions must be given. Fine, small, medium, etc.

A: we had revised the figures in manuscript.

12. Figure 1 has a very low quality. It presents extremely difficult-to-read information. Kindly supply a figure of greater quality.

A: we had revised Figure 1 as follow:

 

13. Paragraphs between lines 148 and 176. First, the electronic links take readers to the Chinese Wikipedia header page. Second, citing Wikipedia in scholarly publications is strongly discouraged. I am sure that many scientists have researched the plant species chosen as the subject of this research. Finding references to these studies will not be a problem.

A: we had revised the references.

14. Add research limitations to the Discussion section.

A: we had added the research limitations in the discussion as follow:

In this study, the soil reinforcement capacity of different vegetation was analyzed only from the aspect of the influence of root structure characteristics on the pull-out force of vegetation. As the intersection of different disciplines such as ecology, soil science, botany, hydrology, soil mechanics, and material mechanics, the mechanism of soil fixation of vegetation roots needs to be further studied. The distribution morphology of the root system is very related to the range of soil consolidation, and the shear and tensile strength of the taproot and lateral roots are different, and the rigidity and flexibility are also different. In the process of research, the soil fixing capacity of vegetation should be comprehensively analyzed in combination with the shear strength of different vegetation roots. At the same time, the understanding of the mechanism of root-soil interface is insufficient, and the numerical simulation of root soil consolidation is still relatively weak in model selection, and the model is relatively simple, so strengthening the research on root soil consolidation foundation is the premise of numerical simulation development. In addition, slope greening and mountain ecological restoration mostly adopt a composite plant system combining grass, shrub and tree, and different plant root systems may have complementary effects on soil fixation. On the basis of the research on soil consolidation of single plant roots, it is a future development trend to carry out research on the soil consolidation mechanism of grass-shrub-tree composite roots.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have revised the manuscript in response to all comments and suggestions. Thanks to the authors for their work.