Effect of Soil Moisture Content on the Shear Strength of Dicranopteris Linearis-Rooted Soil in Different Soil Layers of Collapsing Wall

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The item of the MS is interesting for the readers of Forests since it combines sound soil mechanical observations and modelling approaches with their practical implications for soil preservation techniques in regions prone to landslide formation and gully erosion. Presentation of data in figures and tables is predominantly convincing. But I feel, that in some cases more details or broader explanation in the text could further enhance the value of this study.

The authors presume that terms which are common in China would be as well understood in the international community. E.g. I would appreciate if the term Benggang would be introduced and explained with an internationally common term like “gully ersosion” (see Yujie Wei et all, Catena 2011).

The term “certain soil object” (line 81) is too diffuse. Intended the authors to say “disturbed soil samples”?

The reference on “restoration of soil microbial function in degraded land” (lines 90-91) is unexpected and strange because the target variables of the study are soil physical and soil mechanical ones rather than micro biological.

The methods described at lines 142.152 should be explained in more details

The sentences at line 164-169 are hardly to follow.

The Photos of soil aggregates in Figure 2 (b, c, d) are informative, but it would be important to know how the aggregates were taken (defined strain ?).

It remained unclear to me if the term “bulk density” is wet or dry bulk density and how it was determined. Formula 1 seems to me not to be clear in this context.

It would be helpful to get a detailed overview on the data on dry bulk density, root content and SMC of the material used for the study (individual values, averages and variation) e.g. as table in the supplement. Thus the readers could follow the settings given  in lines 175-177.

I don´t understand the term “RAR” since the root content is given as 0,75 g/100cm^-3 and not per area.

Provoked by the difference between measured and with WWM simulated cohesion (in Fig. 7 should the y-axis be labeled “cohesion” and not “cohesion increment) and the somehow arbitrary correction term k´ I ask myself if this difference can be really interpreted as an “over estimation” (line 280) of WWM caused by SMC and soil properties (the latter is an insufficient, too general and fuzzy term) or if WWM must be seen as a more realistic approach since the measurements are performed with disturbed soil samples. To my experience, disturbed soil sampled loose part of their mechanical properties which applies especially to rooted soil samples, where the conjunction between roots and soil matrix as well as the coherence of soil matrix itself is hampered, since root hairs and mycorrhiza gets at least partially interrupted by disturbed soil sampling. I would appreciate if the authors would discuss the option of sampling naturally layered soil cores with steel rings. I admit that this would cause a much higher methodical effort since no constant root content could be guaranteed and root content must be determined retrospectively at each sample. But a comparison between naturally structured and disturbed, rooted soil cores would give a more specific idea what processes lie behind the correction term k´.

Comments on the Quality of English Language

especially terms should be checked if they fit to internationally common terminology

Author Response

Response to Reviewer #1’s Comments

 

The item of the MS is interesting for the readers of Forests since it combines sound soil mechanical observations and modelling approaches with their practical implications for soil preservation techniques in regions prone to landslide formation and gully erosion. Presentation of data in figures and tables is predominantly convincing. But I feel, that in some cases more details or broader explanation in the text could further enhance the value of this study.

 

The authors would like to thank you for your valuable suggestions. The manuscript has been revised based on your comments. Your kind consideration of the manuscript for publication in Forests is very much appreciated.

 

1. The authors presume that terms which are common in China would be as well understood in the international community. E.g. I would appreciate if the term Benggang would be introduced and explained with an internationally common term like “gully ersosion” (see Yujie Wei et all, Catena 2011).

 

Revised. Please see the tracked changes version of the manuscript

 

2. The term “certain soil object” (line 81) is too diffuse. Intended the authors to say “disturbed soil samples”?

 

Revised. Please see the tracked changes version of the manuscript

 

3. The reference on “restoration of soil microbial function in degraded land” (lines 90-91) is unexpected and strange because the target variables of the study are soil physical and soil mechanical ones rather than micro biological.

 

More attention has been paid to the effect of D. linearis on the restoration of soil microbial function, while less attention has been given to the mechanical properties of D. linearis rooted soil, which highlights the necessity of this topic

 

4. The methods described at lines 142.152 should be explained in more details

 

Revised. Please see the tracked changes version of the manuscript

 

5. The sentences at line 164-169 are hardly to follow.

 

Revised. Please see the tracked changes version of the manuscript

 

6. The Photos of soil aggregates in Figure 2 (b, c, d) are informative, but it would be important to know how the aggregates were taken (defined strain ?).

 

In fact, the purpose of the image is to show the difference in soil color among three layers, not to define aggregates.

 

7. It remained unclear to me if the term “bulk density” is wet or dry bulk density and how it was determined. Formula 1 seems to me not to be clear in this context.

 

Dry bulk density.

Formula 1 is the amount of water added to the soil with the target water content

Formula 2 is the mass of wet soil with bulk density of 1.35

 

8. It would be helpful to get a detailed overview on the data on dry bulk density, root content and SMC of the material used for the study (individual values, averages and variation) e.g. as table in the supplement. Thus the readers could follow the settings given in lines 175-177.

 

Revised, and the table is provided

 

9. I don´t understand the term “RAR” since the root content is given as 0.75 g/100 cm^-3 and not per area.

In this study, the cross-sectional area of the shear strength of the root-soil complex was the bottom area of the ring cutter supported by the direct shear apparatus, which was 30 cm². After the direct shear test was performed, the roots were scanned and classified according to a diameter grade of 0.5 mm. The cross-sectional area of the roots was calculated by the following formula (De Baets et al., 2008):

                                                  (3)

where  represents the root cross-sectional area (cm²); I represents the diameter stage; N represents the number of samples at different diameter classes; and n_i represents the root content of diameter I in the root-soil complex. d_i represents the median diameter (cm) of the root diameter classes.

 

 

10. Provoked by the difference between measured and with WWM simulated cohesion (in Fig. 7 should the y-axis be labeled “cohesion” and not “cohesion increment) and the somehow arbitrary correction term k´ I ask myself if this difference can be really interpreted as an “over estimation” (line 280) of WWM caused by SMC and soil properties (the latter is an insufficient, too general and fuzzy term) or if WWM must be seen as a more realistic approach since the measurements are performed with disturbed soil samples. To my experience, disturbed soil sampled loose part of their mechanical properties which applies especially to rooted soil samples, where the conjunction between roots and soil matrix as well as the coherence of soil matrix itself is hampered, since root hairs and mycorrhiza gets at least partially interrupted by disturbed soil sampling. I would appreciate if the authors would discuss the option of sampling naturally layered soil cores with steel rings. I admit that this would cause a much higher methodical effort since no constant root content could be guaranteed and root content must be determined retrospectively at each sample. But a comparison between naturally structured and disturbed, rooted soil cores would give a more specific idea what processes lie behind the correction term k´.

 

Thanks for your kind advice. Wu and Waldron (Wu, 1976; Waldron and Dakessian, 1981) believed that the root reinforcement effect is mainly expressed by the additional cohesion and proposed the Wu-Waldron model ( the WWM) to calculate it.

Cr = k · Tr · RAR

where Cr represents the cohesion increment (kPa); k is the constant (1.2); Tr is the root tensile strength (MPa); and RAR is the root area ratio (%).

So, the difference between measured and the WWM simulated is cohesion increment.

To be honest, it is a good idea that discussing the option of sampling naturally layered soil cores with steel rings. As you said, there are many uncontrollable factors in the undisturbed soil, which is the key that I am considering and intend to solve in the future. Thank you again for all your effort on this study.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors present the results of a laboratory study on samples prepared in the laboratory and not obtained directly from the field. The results are described, but there is no explanation involving the characteristics of the geological materials and, above all, related to the field capacity and wilting point of the field conditions.

I believe that in the analysis section it is essential to present an evaluation of the results obtained in the laboratory with the field conditions and, above all, with the mechanism of the erosion process.

It is not clear from the manuscript why samples obtained in the field, which would more adequately represent the geological materials and roots, were not studied.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer #2’s Comments

 

The authors would like to thank you for your valuable suggestions. The manuscript has been revised based on your comments. Your kind consideration of the manuscript for publication in Forests is very much appreciated.

 

The authors present the results of a laboratory study on samples prepared in the laboratory and not obtained directly from the field. The results are described, but there is no explanation involving the characteristics of the geological materials and, above all, related to the field capacity and wilting point of the field conditions.

I believe that in the analysis section it is essential to present an evaluation of the results obtained in the laboratory with the field conditions and, above all, with the mechanism of the erosion process.

It is not clear from the manuscript why samples obtained in the field, which would more adequately represent the geological materials and roots, were not studied.

 

Thank you for your kind advice and all efforts. In fact, the collapsing wall is very steep. It is difficult to collect rooted soil in situ, and the root content and SMC of rooted soil are also hard to control. Therefore, this study attempts to investigate the effect of SMC on the shear characteristics of three soils by laboratory test. In addition, the SMC designed in the manuscript was based on the soil water content before and after rain in the field. Therefore, the water capacity and wilting point of soils were not measured, and the data of capillary porosity is supplemented.

 

 

1. Change the title to be more direct and objective!

Thank you for your kind advice. Sorry to tell you that I think the title fits well with the content of the study, and it is reasonable. Can you recommend a better title to me? Thank you again for your help.

 

2. Parameters

In fact, k’ is a parameter applied to correct the Wu and Waldron’s model.

 

3. Line 32, Collapsing due to??? Erosion, gravitational mass movement or both?

It is an erosion phenomenon in which the soil on hillsides is damaged and collapses under the combined action of hydraulics and gravity.

 

4. Line 38, 50 Gg km^-2 a^-1

Revised. Please see the tracked changes version of the manuscript

 

5. Line 45, Collapsing????????????

Yes, collapsing wall and collapsing wall soils are professional terms related to the study of Benggang. Reference:

Wei, Y.J., Liu, Z., Wu, X.L., Zhang, Y., Cui, T.T., Cai, C.F., Guo, Z.L., Wang, J.G., Cheng, D.B., 2021. Can Benggang be regarded as gully erosion? Catena. 207(2), 105648. https://doi.org/10.1016/j.catena.2021.105648.

 

6. Line 47, material falls?Figure 1c

Yes

 

7. Line 47, Figure 1a

The position of the arrow is a colluvial deposit, which is formed by the mixture of soil and rock comes from the collapsing wall. The soil is loose and vulnerable to hydraulic erosion.

 

8. Line 119, belongs to a low mountain valley basin landform.

Revised. Please see the tracked changes version of the manuscript

 

9. Line 122, the annual average temperature and the annual rainfall are approximately 19°C and 1700~1900 mm, respectively.

Yes

 

10. Line 133, The object of study is erosion...?

The purpose of this point is that Benggang erosion is serious in the study area, and its occurrence and development is closely related to the stability of the collapsing wall. Therefore, exploring the shear strength of collapsing wall soils is very important for the treatment of Benggang in this area.

 

11. Line 154，Only 2 cm???

Yes. Field investigation found that after removing 2 cm of the surface layer of the collapsing wall, the soil was fresh and without impurities.

 

12. Line 160

Revised. Please see the tracked changes version of the manuscript

 

13. Line 165，?????

Yes. There was a transition zone of approximately 20–30 cm between each layer, which was avoided during the process of sampling to ensure the difference in soil properties could be observed.

 

14. Line 169，in this way the figure doesn't give a real view of the materials. it could be modified to show them in a more objective and detailed way.

Revised. Please see the tracked changes version of the manuscript

 

15. Line 171，What is the mineralogy of silt???? What is the mineralogy of the silt???? field dry apparent specific weight, void ratio, etc....field capacity, wilting point...............

The types of clay minerals are composed of quartz, kaolinite and illite.

In this study, the experimental design was based on soil water content under natural conditions. field capacity, wilting point and other indexes were not determined, but capillary porosity data were supplemented.

 

16. Line 173，Values for 3 layers?

Yes

 

17. Line 175，very low value!!!!!!!!!!!

It was designed based on the average root weight density of D. linearis (75 g/0.01 m³) in the field investigation.

 

18. Line 186，????

Yes, rooted soil (the root content is 0.75 g 100 cm^-3), and plain soil (the root content is 0.00 g 100 cm^-3)

 

19. Line192，Samples obtained in situ with the roots or those prepared in the laboratory?

prepared in the laboratory

 

20. Line217，The methods and materials section is very straightforward. But the description of the materials is too simple!!!

 

Thank you for your kind advice. The contents related to root material and root tension have been added.

 

 

21. Line228/308，What are the reasons?

This may be affected by the difference of soil properties. The clay content of Lateritic layer is high, and the proper addition of water promotes the agglomeration between particles, and the shear strength of soil increases. As the confining pressure increases, the arrangement of soil particles in the shear box becomes increasingly closely packed, the consolidation coefficient of the soil decreases, the rate of increase in the tightness of the root–soil interface declines, and the growth rate of the shear strength decreases. The results are consistent with those of Huang (2021).

(Huang, M.Y., Sun, S.J., Feng, K.J., Lin, M.Q., Shuai, F., Zhang, Y., Lin, J.S., Ge, H.L., Jiang, F.S., Huang, Y.H., 2021. Effects of Neyraudia reynaudiana roots on the soil shear strength of collapsing wall in Benggang, southeast China. Catena. 210, 105883. https://doi.org/10.1016/j.catena.2021.105883.).

 

22.Line 234，What are the reasons?

At the initial stage of the increase of SMC, most of the water molecules existed in the form of bound water, and its main function was to increase particle cohesion and friction (Fu et al., 2020). When more moisture was added, water molecules existed in the form of free water, which mainly played a role in lubricating the reinforced materials, resulting in a decrease of electromagnetic attraction and cementation between particles (Liu et al., 2021; Harsh Vardhan Singh, 2016).

 

23. Line301，??????

Yes. while soils were under near-saturated conditions, the connection between the soil particles was hardly formed, and the lubrication of moisture accelerated particle sliding, thus reducing the frictional forces, which resulted in a decrease in shear strength at high moisture.

 

24. Line329，?????

Where the threshold is the optimal water content obtained by fitting regression.

 

25. Line335，?????

No, It is moisture content of rooted soil.

 

26. Line376，What is the field capacity???

The field capacity was not measured, but capillary porosity data were supplemented.

 

 

27. Line381，the images do not justify the above explanations!

Revised. Please see the tracked changes version of the manuscript

 

28. Line456, The conclusions should include a comparison with the field characteristics and with the defraction of the erosion process.

Revised. Please see the tracked changes version of the manuscript

 

 

 

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

See the file attached.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

There are some grammatical and typing errors. Authors are asked to have them proofread by a native English speaker.

Author Response

Response to Reviewer #3’s Comments

The authors would like to thank you for your valuable suggestions. The manuscript has been revised based on your comments. Your kind consideration of the manuscript for publication in Forests is very much appreciated.

 

1. Line23，Define!!

Revised. Please see the tracked changes version of the manuscript

 

2. Line38，Write in a complete way without using (-)

Revised. Please see the tracked changes version of the manuscript

 

3. Line60，Explay more about this plant!

Revised. Please see the tracked changes version of the manuscript

 

4. Line62

Revised. Please see the tracked changes version of the manuscript

 

5. Line73，Are you sure? I don't understand! How can a soil rise above saturation? Wouldn't it be an increase in the degree of saturation?

Lian et al. (2019) explored the rooted soil shear strength of Robinia pseudoacacia L. and found that the cohesion of reinforced soil under saturated condition decreased by 50%~61% compared with 16% SMC.

Two experimental designs: soil water content is 16% and saturated, respectively.

 

6. Line83，non lateritic, ok? Could be better explain

Thanks for your kind advice. It is a professional terms related to the study of Benggang. Reference:

Wei, Y.J., Liu, Z., Wu, X.L., Zhang, Y., Cui, T.T., Cai, C.F., Guo, Z.L., Wang, J.G., Cheng, D.B., 2021. Can Benggang be regarded as gully erosion? Catena. 207(2), 105648. https://doi.org/10.1016/j.catena.2021.105648.

 

7. Gravel?

The DL is greyish white and contains considerable quartz sand. The mica minerals that are not completely weathered combine with quartz to maintain the primary granite structure.

 

8. Line143，Post a picture of the separated roots

Revised. Please see the tracked changes version of the manuscript

 

 

1. Line146，What criteria were used to define this length? Was it a % of the shear ring?

Based on the size of ring (the height is 2 cm)

 

10. Line150，Post a photo of the machine performing the pull test!

Revised. Please see the tracked changes version of the manuscript

 

 

2. Line162，I believe that's not the right word.

Revised. Please see the tracked changes version of the manuscript

 

3. Line171，particle size

Revised. Please see the tracked changes version of the manuscript

 

4. Line175，Confusing! Use a different presentation

Revised. Please see the tracked changes version of the manuscript

 

5. Line177，Why did they choose this range of values and not a higher or lower one? And the sample with SMC = 0%?

Field investigation indicated that the water content of collapsing-wall soils was between 15% and 30%. Therefore, SMC was set based on this.

 

15. Line190，What compaction energy was used and how was the ring filled? What are the dimensions of the ring?

The ring volume is 60 cm³. The sample was compacted in three times, the hammer mass was 0.71 kg, the fall height was 0.3 m, and hit 2 to 6 times. The compaction energy was 208.74~626.22 KJ/m³.

 

16. Line192，The samples were consolidated besides the normal stress? If yes, why was the objective?

No, it is the parameter of the direct shear instrument

 

17. Line195，Show all the graphs obtained in the tests.

The shear data of normal stress of 25 kPa, 50 kPa, 75 kPa and 100 kPa were shown

 

18. Line223，It is not necessary! Quit this precision in all datas!

Thanks for your kind advice. Revised. Please see the tracked changes version of the manuscript

 

19. Line230 and 242，Put in the same graph, with and without roots

Sorry to tell you that the graph produced by this method have many lines, resulting in poor visual effects. Therefore, your suggestion was not adopted in the paper. Thank you again for your kind advice and efforts.

 

20. Line250，something wrong.

Revised. Please see the tracked changes version of the manuscript

 

21. Line254，

Revised. Please see the tracked changes version of the manuscript

 

22. Line259，suggest 40, In geotechnics, given the variability and uncertainties, precision is not used

Revised. Please see the tracked changes version of the manuscript

 

23. Line281，How relevant is this difference to a stability project?

Because the SMC was not take into account in WWM, the additional cohesion of root was overestimated. Especially in the SL and DL, the overestimation ratio reaches 22. This not only leads to wrong evaluation of soil reinforcement ability of roots, but also affects the selection and cultivation of plants that improve collapsing wall stability.

 

24. Line297，Did the statistics confirm it?

Yes.

 

Table. Variance analysis of shear strength with different SMC
Normall stress	Soil layer	Without root		With root
		F	P	F	P
25 kPa	Lateritic	33.442	0.000	26.664	0.000
	Sandy	32.751	0.000	17.713	0.001
	Detritus	22.899	0.000	18.712	0.001
50 kPa	Lateritic	24.776	0.000	46.984	0.000
	Sandy	32.884	0.000	18.720	0.001
	Detritus	17.222	0.001	20.654	0.000
75 kPa	Lateritic	18.925	0.001	29.057	0.000
	Sandy	16.836	0.001	10.019	0.004
	Detritus	23.388	0.000	26.135	0.000
100 kPa	Lateritic	28.297	0.000	20.052	0.000
	Sandy	49.393	0.000	39.949	0.000
	Detritus	36.586	0.000	28.754	0.000

 

25. Line396，What effect did the laterization of the soil have when the roots were added?

 

Lateritization is a special process that forms laterite soil under humid and hot climatic conditions. It mainly occurs through the gradual removal of silicon from silicate soils, leading to the accumulation of metals like iron, manganese, and aluminum in the soil, thereby increasing the content of ferric oxide. Factors influencing lateritization mainly include rainfall, temperature, and the parent rock. Regarding plant root, on one hand, It can promote the decomposition and release of soil minerals by organic acids and other root substances; on the other hand, through biomechanical effects, roots improve soil structure, pH, moisture, and temperature conditions, affecting the process of soil desilication and iron-aluminum enrichment.

 

 

26. Line444，Creating equations for soil types based on textures can be very complicated. I believe that the equations should also be associated with particle diameter (e.g. effective diameter), plasticity index, etc. What can the authors say about this?

In fact, the equation is developed from the WWM. In this model, the shear strength of rooted soil is predicted by the plain soil shear strength and root additional cohesion, and it is simplicity and clarity. The limitation of WWM is that only the root system feature, such as tensile strength, is considered, but the soil properties (such as water content, texture) are not taken into account. Therefore, the purpose of this study is to modify the inapplicable part of the WWM by taking SMC as a variable, and establish shear strength equation on 3 soils.

 

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The Authors investigated the effect of SMC on the shear properties of rooted soil in three soils. The works are beneficial for other researchers. It is interesting to see the new study on Dicranopteris linearis roots. However, some major revisions are necessary

1. The roots' zone are normally observed within partially saturated soil zone. Please review the following paper on the influence of partially saturated soil properties on moisture contents variations within root zone. 

https://doi.org/10.1680/jgeen.18.00215

10.1007/s11104-018-3766-7

10.1680/jgeot.19.sip.018

10.1680/envgeo.14.00010

2. Provide explanation why partially saturated soil properties is not considered in the study.

3. The study only focused on one type of plant in China. Please provide explanation how to relate the results of study from the Authors for application in the other parts of the world. Roughly in which country or contintent, the same plant can be found? 

4. Provide some legend and dimension in Figure 2a, 2b, 2c, 2d

5. Provide map showing location of study

6. Provide table summarizing the index properties, hydraulic properties and shear strength properties of soil that is investigated by the Authors

7. Figure 9 is not really clear. Please improve the resolution especially the text in each figure

8. Provide the explanation on the effect of variability of soil moisture due to variations of rainfall in the future on the results of study

Comments on the Quality of English Language

Some typo and grammatical errors should be rectified

Author Response

Response to Reviewer #4’s Comments

 

The authors would like to thank you for your valuable suggestions. The manuscript has been revised based on your comments. Your kind consideration of the manuscript for publication in Forests is very much appreciated.

The Authors investigated the effect of SMC on the shear properties of rooted soil in three soils. The works are beneficial for other researchers. It is interesting to see the new study on Dicranopteris linearis roots. However, some major revisions are necessary

1. The roots' zone are normally observed within partially saturated soil zone. Please review the following paper on the influence of partially saturated soil properties on moisture contents variations within root zone.

https://doi.org/10.1680/jgeen.18.00215

10.1007/s11104-018-3766-7

10.1680/jgeot.19.sip.018

10.1680/envgeo.14.00010

 

Thanks for your kind advice.

 

2. Provide explanation why partially saturated soil properties is not considered in the study.

When the soil is saturated, it is not only difficult to prepare the shear sample, but also the phenomenon of water seepage will occur in the shear test. In addition, the study set a maximum water content based on soil water content in field surveys after rainfall

 

3. The study only focused on one type of plant in China. Please provide explanation how to relate the results of study from the Authors for application in the other parts of the world. Roughly in which country or contintent, the same plant can be found?

Dicranopteris linearis is also widely distributed in Japan, India, Vietnam and other countries. This study not only measured the tensile strength of its roots, but also quantified its soil fixation effect and the relationship between soil consolidation capacity and soil water content, which provided data support for the selection and cultivation of soil and water conservation plants in other areas.

 

4. Provide some legend and dimension in Figure 2a, 2b, 2c, 2d

Revised. Please see the tracked changes version of the manuscript

 

5. Provide map showing location of study

Revised. Please see the tracked changes version of the manuscript

 

6. Provide table summarizing the index properties, hydraulic properties and shear strength properties of soil that is investigated by the Authors

Thanks for your kind advice. I have provided the basic characteristics of the soil in the form of images.

7. Figure 9 is not really clear. Please improve the resolution especially the text in each figure

Revised. Please see the tracked changes version of the manuscript

 

8. Provide the explanation on the effect of variability of soil moisture due to variations of rainfall in the future on the results of study

China's Fourth National Assessment Report on Climate Change shows that in the future, the East Asian monsoon circulation will strengthen, rainfall will increase, and the intensity and frequency of extreme precipitation will increase more significantly, which means that more attention should be given to the layout of drainage facilities when selecting vegetation measures to stabilize collapsing walls.

Provided. Please see the tracked changes version of the manuscript

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors considered the remarks from report 1 thoroughly and enhanced the readability of the MS substantially. I have sill some few minor suggestions before the MS is ready to publication. I would appreciate if in Figure 1 the approximate location where soil samples were taken in the LL, SL and DL layer, would be marked and described in the figure caption. Thus a more clear relation between Figure 1 and Figure 3 could be recognized. I found a little mistake in the labeling of the subgraphs in Figure 10: The right subgraph in the downward row is wrongly labeled as e), but should be obviously f).

I am very content with the constructive answers of the authors to my remarks from the first report with exception with the 10^th concerning the interpretation of WWM and the correction term k´. The authors admit that “it is a good idea that discussing the option of sampling naturally layered soil cores with steel rings” but they state in their answer that they would consider that item and “intend to solve it in the future” because there are to expect “many uncontrollable factors in the undisturbed soil”. I would appreciate if a short paragraph would be added at the end of the discussion where the potential uncertainty of the interpretation of WWM and k´ caused by disturbing soil structure through the sampling method and the preparation of soil samples would be discussed. In the following some few examples of literature on the potential influence of root hairs and/or hyphae on aggregate stability and soil cohesion

Plant Soil (2022) 476:491–509, https://doi.org/10.1007/s11104-022-05530-1

Wu, QS., Cao, MQ., Zou, YN. et al. Direct and indirect effects of glomalin, mycorrhizal hyphae and roots on aggregate stability in rhizosphere of trifoliate orange. Sci Rep 4, 5823 (2014). https://doi.org/10.1038/srep05823

Role of root-hairs and hyphae in adhesion of sand particles, October 2007, Soil Biology and Biochemistry 39(10):2520-2526 DOI: 10.1016/j.soilbio.2007.04.021

Nicolai Koebernick, Keith R. Daly, Samuel D. Keyes, Timothy S. George, Lawrie K. Brown, Annette Raffan, Laura J. Cooper, Muhammad Naveed, Anthony G. Bengough, Ian Sinclair, Paul D. Hallett, Tiina Roose: New Pytologist (2017) High-resolution synchrotron imaging shows that root hairs influence rhizosphere soil structure formation. https://doi.org/10.1111/nph.14705

Sarah De Baets et al. COMMUNICATIONS BIOLOGY | (2020) 3:164 | https://doi.org/10.1038/s42003-020-0886-4 | www.nature.com/commsbio

 

Concluding I rate the MS in its present state as ready for publication after minor revision

Comments on the Quality of English Language

fine, some minor roughness could be eliminated, but this is not essential

Author Response

Response to Reviewer #1’s Comments

 

1. The authors considered the remarks from report 1 thoroughly and enhanced the readability of the MS substantially. I have sill some few minor suggestions before the MS is ready to publication. I would appreciate if in Figure 1 the approximate location where soil samples were taken in the LL, SL and DL layer, would be marked and described in the figure caption. Thus a more clear relation between Figure 1 and Figure 3 could be recognized. I found a little mistake in the labeling of the subgraphs in Figure 10: The right subgraph in the downward row is wrongly labeled as e), but should be obviously f).

 

First of all, thank you very much for your suggestion on the modification of the picture.

With regard to figure 1, the author intends to better show and introduce the shape and composition of the Benggang to the reader through this diagram. The sampled Benggang is another, which has dense vegetation and poor picture shooting effect, so it is only partially presented in the form of figure 3. Based on this, the author is unable to mark the sampling points in figure 1. Sincerely hope to get your understanding and support.

Figure 9, revised. please see the tracked changes version of the manuscript

 

 

2. I am very content with the constructive answers of the authors to my remarks from the first report with exception with the 10^thconcerning the interpretation of WWM and the correction term k´. The authors admit that “it is a good idea that discussing the option of sampling naturally layered soil cores with steel rings” but they state in their answer that they would consider that item and “intend to solve it in the future” because there are to expect “many uncontrollable factors in the undisturbed soil”. I would appreciate if a short paragraph would be added at the end of the discussion where the potential uncertainty of the interpretation of WWM and k´ caused by disturbing soil structure through the sampling method and the preparation of soil samples would be discussed. In the following some few examples of literature on the potential influence of root hairs and/or hyphae on aggregate stability and soil cohesion

 

Revised. please see the tracked changes version of the manuscript in line 428.

Thank you for your suggestions and references here, and I am honored to receive your guidance and thank you for all your efforts to this manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has undergone some changes that have led to improvements. The manuscript is now ready to be accepted for publication. 

Author Response

Response to Reviewer #2’s Comments

 

The manuscript has undergone some changes that have led to improvements. The manuscript is now ready to be accepted for publication.

 

The authors would like to thank you for your valuable suggestions. The manuscript has been revised based on your comments. Your kind consideration of the manuscript for publication in Forests is very much appreciated.

Reviewer 4 Report

Comments and Suggestions for Authors

The Authors have addressed some comments, but certain comments were not addressed properly. Currently, the paper can not be accepted. Please address comments number 1 and number 2 from previous comments correctly. 

 

Comments on the Quality of English Language

A lot of typo and grammatical errors need to be corrected

Author Response

Response to Reviewer #4’s Comments

 

The Authors investigated the effect of SMC on the shear properties of rooted soil in three soils. The works are beneficial for other researchers. It is interesting to see the new study on Dicranopteris linearis roots. However, some major revisions are necessary

1. The roots' zone are normally observed within partially saturated soil zone. Please review the following paper on the influence of partially saturated soil properties on moisture contents variations within root zone.

 

https://doi.org/10.1680/jgeen.18.00215

10.1007/s11104-018-3766-7

10.1680/jgeot.19.sip.018 

10.1680/envgeo.14.00010 

 

Thank you for your literature, which has been referenced and added to the discussion section of the manuscript. please see the tracked changes version of the manuscript in line 306

 

2. Provide explanation why partially saturated soil properties is not considered in the study.

 

In the field investigation, the root-soil complex mainly exists in the form of unsaturated soil, which will be considered in the future study.

Thank you again for your patience and careful guidance.

Author Response File: Author Response.pdf