Topography and Soil Properties Determine Biomass and Productivity Indirectly via Community Structural and Species Diversity in Karst Forest, Southwest China

Round 1

Reviewer 1 Report

The paper aimed to analyze the biomass and productivity of forest ecosystems, and their driving factors. The topic is interesting, while some probelms should be concerned.

(1) Title, should be revised to "Topography and soil properties determine biomass and productivity indirectly via community structural and species diversity in karst forest, southwest China "

(2) Line 55-59, The sentence is too long, please rewrite.

(3) Line 55-66, Sustainable forest management has nothing to do with the previous and subsequent texts, and it is meaningless to put it in the introduction.

(4) Line 94, "with the characteristics of ecosystem stability and strong heterogeneity of habitat",  ecosystem stability what? weak?

(5) Line209-210, "Principal components analysis (PCA) was used to analyze topographic factors, soil factors, species diversity and structural diversity", analyze what? relationship?

(6) Line211, "tree diversity" or "species diversity"?

(7) Table A1 is missing.

(8) In discussion, How soil factors affect biomass and productivity are missing, this need deep discussion.

(9) The research conclusion is too long. Please summarize your real conclusion.

（10）According to your research results, you can put forward the Enlightenment of forest sustainable management. 

Author Response

Point 1: Title, should be revised to "Topography and soil properties determine biomass and productivity indirectly via community structural and species diversity in karst forest, southwest China "

Response 1: Thanks very much for your suggestion, we have revised.

Point 2: Line 55-59, The sentence is too long, please rewrite.

Response 2: Yes, we have revised.

Point 3: Line 55-66, Sustainable forest management has nothing to do with the previous and subsequent texts, and it is meaningless to put it in the introduction.

Response 3: Thanks very much for your suggestion, we have deleted.

Point 4: Line 94, "with the characteristics of ecosystem stability and strong heterogeneity of habitat", ecosystem stability what? weak?

Response4: Thanks very much for the careful review. We have added.

Point 5: Line209-210, "Principal components analysis (PCA) was used to analyze topographic factors, soil factors, species diversity and structural diversity", analyze what? relationship?

Response 5: "The principal components analysis"(PCA) of species diversity, structural diversity, soil nutrients, and topographic factors is mainly to reduce the dimensionality of these variables

Point 6: Line211, "tree diversity" or "species diversity"?

Response 6: It refers to species diversity.

Point 7: Table A1 is missing.

Response 7: We have added.

Point 8: In discussion, How soil factors affect biomass and productivity are missing, this need deep discussion.

Response 8: Yes, Thanks very much. We have discussed this section in more depth. Please see in line 406-431

Point 9: The research conclusion is too long. Please summarize your real conclusion.

Response 9: Yes, we have deleted and summarize some words.

Point 10: According to your research results, you can put forward the Enlightenment of forest sustainable management.

Response 10: We have added the implication in the revision. Please see in line 476-486

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript is well written, but it requires some improvements. Please double-check the writing.

1.     Line 41: Please use alphabetical order to arrange these keywords.

2.     Line 49: It is better to replace reference 3 with Pan, et al. (2011).

3.     Line 55-65: It is better to include a brief statement related to the harvesting (Zhao, et al. 2020) and disturbances (insect, fire, please look for one or two papers.).

4.     Line 78-90: In my understanding, the forest structure is a broad concept. It refers to age structure, size structure, or species structure. Please make it clearer. In addition, I think the age of a forest ecosystem greatly affects its biomass/carbon storage and production. The biomass of different forest ecosystems may reach their peaks at different ages (Diao, et al. 2022). In another word, similar size structures may have different production rates. Please include it.

5.     Line 120: Please add a map of your study area and show plot locations.

6.     Line 192: In this study, the biomass is the total biomass or the above-ground biomass? Equation 1 is generally used to estimate the AGB. Please make sure that. See line 303, it is AGB.

7.     Line 248: The P-value is easily controlled by the sample size. Please use a bootstrapping method to recalculate the P-value.

8.     Line 292: Nice figure.

9.     Line 303: AGB or total biomass?

10.  Line 310: Citation for the 152.88 Mg / ha.

11.  Line 388: was – is, please use the present tense.

12.  Discussion: Please discuss the limitations of your study. The current analysis is insufficient to analyze the interactions among these environmental factors. It is required to discuss the limitations of your study.

1.        Pan, Y., Birdsey, R.A., Fang, J., Houghton, R., Kauppi, P.E., Kurz, W.A. et al. 2011 A large and persistent carbon sink in the world’s forests. Science, 333 (6045), 988-993.

2.         Zhao, J., Daigneault, A. and Weiskittel, A. 2020 Forest landowner harvest decisions in a new era of conservation stewardship and changing markets in Maine, USA. Forest Policy and Economics, 118, 102251.

3.         Diao, J., Liu, J., Zhu, Z., Wei, X. and Li, M. 2022 Active forest management accelerates carbon storage in plantation forests in Lishui, southern China. Forest Ecosystems, 9, 100004.

Author Response

Point 1: Line 41: Please use alphabetical order to arrange these keywords.

Response 1: Thanks very much. We have revised.

Point 2: Line 49: It is better to replace reference 3 with Pan, et al. (2011).

Response 2: Thanks for your suggestion. We have revised.

Point 3: Line 55-65: It is better to include a brief statement related to the harvesting (Zhao, et al. 2020) and disturbances (insect, fire, please look for one or two papers.)

Response 3: Yes, we have added a brief statement related to disturbances about forest fire. Please see in line 54-57.

Point 4：Line 78-90: In my understanding, the forest structure is a broad concept. It refers to age structure, size structure, or species structure. Please make it clearer. In addition, I think the age of a forest ecosystem greatly affects its biomass/carbon storage and production. The biomass of different forest ecosystems may reach their peaks at different ages (Diao, et al. 2022). In another word, similar size structures may have different production rates. Please include it.

Response 4: We have provided more detail about community structure diversity, and added the effect forest ecosystem age on biomass/carbon storage and production. Please see in line 78-80 and 84-87.  

Point 5：Line 120: Please add a map of your study area and show plot locations.

Response 5: Yes, we have added a location map of the study area, please see Figure 1.

Point 6：Line 192: In this study, the biomass is the total biomass or the above-ground biomass? Equation 1 is generally used to estimate the AGB. Please make sure that. See line 303, it is AGB.

Response 6: The biomass is the above-ground biomass. Yes, equation 1 is generally used to biomass, and the change in biomass accumulation from 2007 to 2017 was used to measure productivity.

Point 7：Line 248: The P-value is easily controlled by the sample size. Please use a bootstrapping method to recalculate the P-value.

Response 7：After the data were normalized by log, P-value were all significant by ANOVA.

Point 8：Line 292: Nice figure.

Response 8: Thanks very much.

Point 9：Line 303: AGB or total biomass?

Response 9: Forest above-ground biomass (AGB)

Point 10：Line 310: Citation for the 152.88 Mg / ha.

Response 10: Thanks very much. We have added.

Point 11：Line 388: was – is, please use the present tense.

Response 11: Thanks very much for the careful review. We have revised.

Point 12: Discussion: Please discuss the limitations of your study. The current analysis is insufficient to analyze the interactions among these environmental factors. It is required to discuss the limitations of your study.

Response 12: Yes, we have added. Please see in line 466-474.

Author Response File: Author Response.docx

Reviewer 3 Report

The present research paper focused on karst forests in southwest China, exploring the structure and species diversity of karst forests to determine biomass and productivity through  the analysis and assessment of topography and soil, with the following objectives What are the dynamic changes of forest biomass and productivity in the primary forest; Species diversity or structural diversity impact on biomass and productivity?; How do topographic and soil factors affect changes in biomass and productivity?. I have the following comments and suggestions for including information and improvements:

Abstract

I suggest that the authors add more information about the methods and results values (regression adjust). The current abstract does not contain information on this aspect, making it a fragile abstract.

Keywords: I suggest that authors include keywords not already contained in the title. This may help readers locate this article more efficiently as it has a broader range of search terms.

Introduction

The authors should illustrate more about the state of the art in relationship between biodiversity and productivity. Citations should be included between lines 55 – 77.

A more explicit justification must be included regarding the importance of testing the model in another context (i.e., vegetation types, other ecosystems, biomes) and countries. This information is essential to give a more general aspect to the study, helping it not to appear that the results have only of local importance.

Another critical point that will bring more information to the reader is to describe directly and with greater clarity the objectives of the work. Of course, when reading the complete introduction, we know what the objective is. However, making it more explicit will help readers understand the work's importance and the hypotheses tested.

Methods /

More details must be included in the Materials and Methods in all the subsections. Specifically, I would like to see more details about the criteria for choosing Topographic Variables, Soil Variables, Species, and Community Structure Diversity index.

A location map of the study area must be included, and a flowchart with details on the Field survey, Topographic Variables, Soil Variables, and Statistical Analysis. This will significantly help readers of the article understand the scope of the study in spatial terms and concern the data collection design.

The Biomass and Productivity Model test section must include which tests were performed to assume the linear regression model. I refer specifically to assumptions tests of the linear model as Normal distribution of residuals and homoscedasticity (homogeneity of variances). This information must be available in all adjustments.

When looking at the regressions, adjustments in figure 1 show overdispersion in the points, indicating that the linear model may not be the most appropriate for this estimated relationship between PCA  loading and structural diversity and plant biomass and productivity.  What exactly do the authors think about it?  A suggestion is to make a selection of models by the Akaike criterion (AIC) and test which model is more plausible, inserting nonlinear models (GAM), null models (absence of relationship), and models with different errors distributions such as GLM between others.

Did you correct the Alpha value for the significance of p in the regressions? You did several tests with the same dataset, so there is a need to correct the alpha value. One suggestion is the Bonferroni correction.

Disscution

Citations that give conceptual support to the results found in this section must be included. It is also imperative that the authors include a topic that compares the results found from the methods and analyses proposed in the article with the literature results.

Conclusions

In this section, I suggest that information be added about future advances  and their possible applications  in this field of research, based on the results found in this article.

Author Response

Abstract

Point 1: I suggest that the authors add more information about the methods and results values (regression adjust). The current abstract does not contain information on this aspect, making it a fragile abstract.

Response 1: Thanks for your suggestion, we have added more information about the methods. Please see in line 22-26. In addition, please see the results information in line 26-37.

Keywords

Point 2: I suggest that authors include keywords not already contained in the title. This may help readers locate this article more efficiently as it has a broader range of search terms.

Response 2: Yes, we agree with the reviewer. We have revised.

Introduction

Point 3: The authors should illustrate more about the state of the art in relationship between biodiversity and productivity. Citations should be included between lines 55 – 77.

Response 3: Thanks for your valuable suggestions, and we have supplemented. Please see in line 64-69 and 74-77.  

Point 4: A more explicit justification must be included regarding the importance of testing the model in another context (i.e., vegetation types, other ecosystems, biomes) and countries. This information is essential to give a more general aspect to the study, helping it not to appear that the results have only of local importance.

Response 4: Thanks for your suggestions, we have added the importance of studying the vegetation productivity of large plots under special karst vegetation types and geological conditions. Please see in line 107-111.

Point 5: Another critical point that will bring more information to the reader is to describe directly and with greater clarity the objectives of the work. Of course, when reading the complete introduction, we know what the objective is. However, making it more explicit will help readers understand the work's importance and the hypotheses tested.

Response 5: Thanks for your valuable suggestions. We have added the need to study the effects of species diversity, structural diversity and environmental factors on productivity and biomass at the end of each paragraph. In addition, the middle of the transition of the current status of productivity research, and the last paragraph clearly introduces the objective of this study.

Methods

Point 6: More details must be included in the Materials and Methods in all the subsections. Specifically, I would like to see more details about the criteria for choosing Topographic Variables, Soil Variables, Species, and Community Structure Diversity index.

Response 6: Thanks for your valuable suggestions, we have added more details in the statistical Analysis. Please see in line 225-228.

Point 7: A location map of the study area must be included, and a flowchart with details on the Field survey, Topographic Variables, Soil Variables, and Statistical Analysis. This will significantly help readers of the article understand the scope of the study in spatial terms and concern the data collection design.

Response 7: Yes, we have added a location map of the study area, please see Figure 1. For details on the Field survey, Topographic Variables, Soil Variables, and Statistical Analysis, please see section 2.2 and 2.3

Point 8: The Biomass and Productivity Model test section must include which tests were performed to assume the linear regression model. I refer specifically to assumptions tests of the linear model as Normal distribution of residuals and homoscedasticity (homogeneity of variances). This information must be available in all adjustments.

Response 8: Thanks very much, the data were normalized by log and satisfied homogeneity of variance and normal distribution. Please see in line 225-228

Point 9: When looking at the regressions, adjustments in figure 1 show overdispersion in the points, indicating that the linear model may not be the most appropriate for this estimated relationship between PCA  loading and structural diversity and plant biomass and productivity.  What exactly do the authors think about it? A suggestion is to make a selection of models by the Akaike criterion (AIC) and test which model is more plausible, inserting nonlinear models (GAM), null models (absence of relationship), and models with different errors distributions such as GLM between others.

Response 9: Thanks very much, we think the R² presented by the data is large enough and the P value is significant. At the same time, quadratic fitting and nonlinear fitting are done, and the overall fitting effect of linear regression is better by comprehensive comparison.

Point 10: Did you correct the Alpha value for the significance of p in the regressions? You did several tests with the same dataset, so there is a need to correct the alpha value. One suggestion is the Bonferroni correction.

Response 10: Thanks very much. In the linear regression, there was only one independent variable and dependent variable, and the data had been standardized. Bonferroni analyzed more than two variables, and there was a statistical difference between them. However, the difference disappeared after correction.

Disscution

Point 11: Citations that give conceptual support to the results found in this section must be included. It is also imperative that the authors include a topic that compares the results found from the methods and analyses proposed in the article with the literature results.

Response 11: Yes, Thanks for your suggestion. We have revised the discussion section.

Conclusions

Point 12: In this section, I suggest that information be added about future advances and their possible applications in this field of research, based on the results found in this article.

Response 12: Thanks for the sugggestion. We have added the implication based on the results found in this article. Please see in line 476-486.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The author has made substantial reversion according to the comments, therefore, I recommend accept in present form.

Author Response

Thank you very much

Reviewer 2 Report

The manuscript is well revised. But some corrections are still required.

Line 32: Delete (PCA1) and (PCA2).

Line 35: Please give the full name of TN.

Line 169: Please add the plot location on the figure.

Line 235: In equation 1, please use AGB. The BIO is too confused. In your study, the biomass is AGB, right? In the results section, the biomass is AGB. Please make it clear.

Line 287: When your sample size is more than 30. It is unreasonable to calculate the P-value with all samples. The P-value can be controlled by the sample size. See White et al. (2014). Please randomly select 30 samples to calculate the P-value and repeat this process 500/1000 times (bootstrapping). Report the average P-values in your manuscript.

White, J.W., Rassweiler, A., Samhouri, J.F., Stier, A.C., White, C., 2014. Ecologists should not use statistical significance tests to interpret simulation model results. Oikos 123, 385-388.

Author Response

Point 1: Line 32: Delete (PCA1) and (PCA2).

Response 1: Yes, We have deleted.

Point 2: Line 35: Please give the full name of TN.

Response 2: Yes, We have added.

Point 3: Line 169: Please add the plot location on the figure.

Response 3: Yes, We have added.

Point 4: Line 235: In equation 1, please use AGB. The BIO is too confused. In your study, the biomass is AGB, right? In the results section, the biomass is AGB. Please make it clear.

Response 4: Thanks for your suggestion, we have used AGB

Point 5: Line 287: When your sample size is more than 30. It is unreasonable to calculate the P-value with all samples. The P-value can be controlled by the sample size. See White et al. (2014). Please randomly select 30 samples to calculate the P-value and repeat this process 500/1000 times (bootstrapping). Report the average P-values in your manuscript.

Response 5: Thanks for your suggestion, we have recalculated the P values.

Reviewer 3 Report

Thanks for the authors made efforts to revise the manuscript. The manuscript can be published in the current form in the Journal.

Author Response

Thank you very much

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.