A Compatible Estimation Method for Biomass Factors Based on Allometric Relationship: A Case Study on Pinus densata Natural Forest in Yunnan Province of Southwest China

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In order to validate the study, information about e.g. biomass sampling and determination of tree components mass, volume etc are of great importance. You state that you use the biomass determination method provided in Xu and Zhang [33]. I tried to fint this paper to check methods, but I cant find it in common databases, and I suspect the paper to be non-reacaible for an international community.  I suggest you to revise the paper using references that can be found and read internationally in order to make it possible to review the quality and relevance of your work.

Some other comments:

DBH means diameter at breast height. Breast height is relative. Specify breast height!

You must define and specify units of different properties, e.g. volume. For example, stem volume can be given on bark or under bark, bulk or solid volume etc etc. There are also many parameters in M&M not defined at all!

Comments on the Quality of English Language

The paper need text editing work done by professionals.

Author Response

Response to Reviewers 1

Dear Reviewers and Editor,

we would like to extend my heartfelt appreciation to reviewers and editor for the dedicated efforts and valuable time spent on our manuscript entitled "A compatible estimation method for biomass factors based on allometric relationship: a case study on Pinus densata natural forest in Yunnan province of Southwest China" (forests-2716898). Please find my revisions in the "Revision, changes marked" and "Manuscript" files.

1. In order to validate the study, information about e.g. biomass sampling and determination of tree components mass, volume etc are of great importance. You state that you use the biomass determination method provided in Xu and Zhang [33]. I tried to fint this paper to check methods, but I cant find it in common databases, and I suspect the paper to be non-reacaible for an international community. I suggest you to revise the paper using references that can be found and read internationally in order to make it possible to review the quality and relevance of your work.

Response: Thank you for your comment. More details about the forest sample plots investigation methods has been added. The contents were as below:

The data was derived from sample plots of the natural forest of Pinus densata in Shangri-La City. A total of 98 sample plots were investigated using the individual tree measurement method. Because the factors such as age, elevation, slope, and slope direction had great influence on the growth of trees, the forest compartments with uniform age, species composition, crown structure, elevation, slope, and aspect were generated by visual interpretation method using the spatial distribution map of Pinus densata forest. Within each plot, coordinates, elevation, slope, and aspect were obtained. The fundamental tree factors such as tree species, diameter at breast height (1.3 m) (DBH) and tree height (H) were measured for calculating the tree biomass. Totally 100 sample trees were selected from plots with different forest characteristics to be felled, and wood, bark, branches, needle biomass, DBH and H were measured. Taken a 3 cm thick disc every 2 m along the trunk and calculated the volume. The disc was dried to a constant weight at 105 ℃ and weighed. The sample density was measured using the drainage method. The biomass of trunk and bark per 2 m section was converted from density values. The branches were graded by every 20 cm, and the fresh weight of the branches and foliage was weighted, and then dried in the same way as trunk. The roots were all dig out, and the root system was determined by the full weighing method, recording the root length and basal diameter of the primary root, the biomass of the primary root was weighed in sections and then sampled, and the lateral roots were fully weighed and then sampled. The root was dried in the same way as trunk. The biomass was calculated based on the fresh weight and dry matter ratio. Finally, adding up he biomass of wood, bark, branches and foliage to the total biomass of a single sample tree.

2. DBH means diameter at breast height. Breast height is relative. Specify breast height! You must define and specify units of different properties, e.g. volume. For example, stem volume can be given on bark or under bark, bulk or solid volume etc etc. There are also many parameters in M&M not defined at all!

Response: Thank you for your rigorous remanding. We forgot to add the volume data in the table. The revised version is as below.

Table 1. Min, max, mean, and standard deviation (SD) of diameter at breast height (D_g), tree height (H_m), and wood volume (Vw) of sample plots.

3. Comments on the Quality of English Language

The paper need text editing work done by professionals.

Response: We sincerely appreciate your advice. We’ve improved and rewrote the whole text under the supervision of an English native speaker.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

General comments:

Overview and general recommendation:

It is true that calibration and application above and below ground biomass (AGB) models increases the accuracy and the level of details (tier 3 in IPCC LULUCF sector) when the countries have to write and submit the annual reports for GHG emissions and sings in the UN. Above ground biomass models are useful for predicting with much accuracy the dry biomass of individual trees and forested areas contributing to a better understanding of the carbon sequestration locally and globally. The aim of this article was to estimate the biomass at a large-scale using biomass expansion factors (BEF) and biomass conversion and expansion factor (BCEF) as well as various ratios of different tree biomass components and having as independent variables the mean height and quadratic mean diameter of the stand for Pinus densata plots in Shangri-La, Yunnan province, China.

The Authors tried to present their work comprehensively which, I think it is a good idea. On one hand I found the idea and the methods in this manuscript overall interesting. However, there are problems and serious flaws in the text especially in English language which is poor and needs improvement. There are a lot of sentences where the meaning is not clear. Generally, it is difficult for the reader to follow the meaning of many paragraphs. Some parts of the manuscript that are in the M & M sections must be improved and be more detailed. The discussion section is poor and not well documented. The manuscript cannot be published in the present form unless the authors revise it substantially.

I strongly suggest the authors to revise the manuscript according to my comments and go through grammatical and linguistic editing by a native English speaker.

Therefore, I recommend that a major revision is warranted. I explain my concerns in more detail below and I ask the authors address my comments in their response.

Specific comments:

Line 16

“…crow” -> Do you mean crown?

Lines 28-29

Meaning not clear, please clarify

Line 45

Meaning not clear, please clarify.

Line 54

“…total dry weight of the ground …” Do you mean above ground?

Line 105

I would prefer the more proper term “light demanding species”

Line 107

The authors here must be more specific regarding the estimation of biomass. The citation of Xu and Zhang is not enough to the reader to figure out how the dependent variables are calculated. A more detailed description of the methodology is needed along with the biomass equations. It should be clear how the various forms of dependent variables were estimated.

Lines 155-156

The meaning is not clear, this sentence needs to be re-written

Lines 161-162

More explanation for Rs needs to be added here

Formulae (38) and (39) are well known and it is not necessary to write them explicitly.

Line 189

Table 3 title must be change.

Line 208

Table 4 title is it fitting results? Or parameters?

Line 242

Dm -> Dg

Line 266

“… same dimensional…” Do you mean dimension?

Lines 299-304

This sentence is too long, the meaning is difficult to be followed by the reader, needs to be re-written.

 The discussion section is confusing and makes the reading difficult. Discission needs to be re-written using simpler and smaller sentences and the whole manuscript must be checked linguistically by a native English speaker.

Comments on the Quality of English Language

See my comment for lines 299-304 as an example of long and complicated sentence that is difficult for the reader to follow:

As shown in Figure3, the estimation results had no significant difference between the independent model and compatible model for total biomass, while, the predicted result of the independent model for branch and crown was slightly higher than the compatible model, the results of the other components were nearly the same for both models, indicating those two models not only can be used for the total biomass estimation but also the different components. The result was consistent with Atticus’s research[38].

The discussion section has many sentences with bad use of English language. This is why I urge the authors to re-write the discussion using smaller and simpler sentences and give the manuscript to a native English speaker to check it linguistically.

Author Response

We rectified as requested by the reviewers and answered  the questions raised by the reviewer one by one. The whole text was rewrited and we’ve improved and rewrote the whole text under the supervision of an English native speaker.

Reviewer 3 Report

Comments and Suggestions for Authors

Several questions and remarks regarding the article by Li et al. “A compatible estimation method for biomass factors based on allometric relationship: a case study on Pinus densata natural forest in Yunnan province of Southwest China”.

The research was conducted in a mountainous region. On the sample plots, what were the slope gradients and slope exposure? These factors affect how woody plants develop and grow, which in turn affects the amount of biomass accumulated. Did you include these parameters in the calculations?

Please provide additional details about the forests investigated. What was the species composition of the forests? Were they pure pine forests? Were these primary or secondary forests?

What was the age of the examined trees? Biomass accumulation is directly correlated with the age of the trees. Why was the age of the trees undetermined and not considered in the analysis? To what extent do the biomass coefficient models that are computed fluctuate with the age of the tree stand?

When describing the biomass determination method, the authors refer to the book by Xu and Zhang (2002). Could you help explain the biomass determination process, as it is more difficult to obtain books than published articles? Did the direct destructive method (chopping down trees and measuring the biomass of their separate parts) determine the biomass of the trees? How was the biomass of the root systems of trees measured?

Author Response

We rectified as requested by the reviewers and answered  the questions raised by the reviewer one by one. The whole text was rewrited and we’ve improved and rewrote the whole text under the supervision of an English native speaker.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Please open the attachment file.

General comments
The authors presented a method for calculating BEF and BECF analytically based on the biomass ratios of various tree components. According to the authors, the method is intended to ensure biomass additivity, i.e. the correspondence between the sum of the estimated biomasses of the components and the total biomass of the forest. I am not sure that such a phenomenon will occur if models with different explanatory variables are used to model biomass and biomass ratios.
The solution presented is undoubtedly interesting and should be tested on other data by a wider range of researchers. For this reason, the submitted article seems to be valuable and should be published. Unfortunately, there are many understatements and mental shortcuts in the content of the article. Many of the cited literature items are inaccessible (e.g., the key one for the entire paper describing the methodology for estimating biomass components of individual trees) or are in Chinese. Instead of citing such items, knowing that most readers will find them out of reach, the authors should rather describe them briefly.
I am not a native English speaker, so I do not want to judge the quality of the text, but in my opinion the authors use specific expressions, often too sophisticated language that can be understood in many ways. In my opinion, the entire text requires thorough rewriting, with particular attention paid to the appropriate vocabulary regarding forest biomass modeling issues.
To sum up the above, I recommend that the article be published but after introducing thorough language changes and supplementing the descriptions of the methodology with short summaries instead of quoting the literature in Chinese. In my opinion, the article requires major corrections.
Specific comments
Line 39: What does it mean „…to convert component biomass into forest biomass…”? Please explain this question.
Line 45: Correct article citation.
Lines 58-60: Please describe the methods mentioned in a little more detail because the literature referred to by the authors is in Chinese and will be a barrier for most readers. I wonder about the listed method names, where and when were they named this way? Please also refer to English-language literature e.g.: Affleck, D. L. R., & Diéguez-Aranda, U. (2016). Additive Nonlinear Biomass Equations: A Likelihood-Based Approach. Forest Science, 62(2), 129–140., Reed, D. D., & Green, E. J. (1985). A method of forcing additivity of biomass tables when using nonlinear models. Canadian Journal of Forest Research, 15(6), 1184–1187., Bronisz, K., Bijak, S., Wojtan, R., Tomusiak, R., Bronisz, A., Baran, P., & Zasada, M. (2021). Seemingly Unrelated Mixed-Effects Biomass Models for Black Locust in West Poland. Forests, 12(3), 380., Zhao, D., Westfall, J., Coulston, J. W., Lynch, T. B., Bullock, B. P., & Montes, C. R. (2019). Additive biomass equations for slash pine trees: comparing three modeling approaches. Canadian Journal of Forest Research, 49(1), 27–40.
Line 64: Please use the term "belowground".
Lines 67-73. Sentence too long, rewrite the text.
Lines 74-80: All of the literature mentioned presents allometric equations in which the explanatory variables are diameter at breast height and total tree height. I do not understand whether the
content of this paragraph is a presentation of already published research or a proposal by the authors of this manuscript.
Line 87: Please use the term "allometric equation" for functions of the form y=b0*x^b1
Line 92: I don't understand the second purpose. Please explain what the authors intend to achieve.
Lines 113-114: The indicated literature is unavailable. Without a description of the biomass measurements that are the subject of this article, it cannot be accepted for publication.
Line 114: Did the biomass equations used ensure the additivity of the biomass components?
Line 115: The collection of sample plots was randomly divided…
Line 118: „… of average breast height (Dg), mean tree height…”
Line 119: What the term „harvested sample plots”?
Line 126: Please correct ECEF to BCEF.
Line 128: What does stand volume mean? Does it mean the volume of trunks with a certain diameter limit?
Line 154: The title should emphasize that these are independent models for determining biomass and biomass factors.
Line 160: Was heteroskedasticity taken into account when fitting the models? How was this problem addressed? Since Dg and Hm are correlated was collinearity between these variables taken into account?
Line 169: „…tested models...”? Please clarify whether the authors mean independent or additive models.
Line 189: ??????
Line 206: „different dimensions” ????
Lines 225-227: I don't understand.
Line 381: Were all 98 used to build the model?

Author Response

We rectified as requested by the reviewers and answered  the questions raised by the reviewer one by one. The whole text was rewrited and we’ve improved and rewrote the whole text under the supervision of an English native speaker.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

manus is now OK

Author Response

Dear Reviewers and Editor,

we would like to extend my heartfelt appreciation to reviewers and editor for the dedicated efforts and valuable time spent on our manuscript entitled "A compatible estimation method for biomass factors based on allometric relationship: a case study on Pinus densata natural forest in Yunnan province of Southwest China" (forests-2716898). Please find my revisions in the "Revision, changes marked" and "Manuscript" files.

Response: Thank you for your swift review and positive feedback on the manuscript. We appreciate your careful evaluation. We are pleased to hear that the manuscript is now considered okay.

Your comments and suggestions have been invaluable in improving the quality of our work. If there are any additional steps or revisions you recommend, please feel free to let us know.

Once again, thank you for your time and constructive input.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

General comments:

Overview and general recommendation:

The authors have changed many parts of the text and tried to improve the manuscript linguistically, but the manuscript still needs more linguistic improvement. I found that the manuscript has improved a lot and therefore, I recommend that a minor revision is warranted. I explain my concerns in more detail below and I ask the authors address my comments in their response.

Specific comments:

The line numbers are referred to the revised manuscript with the revisions accepted.

Lines 68,71,73

I prefer to use the term segregate instead of disaggregate.

Line 76

…due to the fact that the root biomass estimation survey

Line 96

To validate the ….

Line 129

The roots were all dug out

Line 134

adding up the biomass

Do you mean that the wood, bark, branches and foliage biomass summed up to give the total biomass of a single sample tree? Please rephrase it

Line 136

The equation is shown in…

Line 137

There are no BEF BCEF factors in eq. 1 Are there other equations that have to be included here and are missing? Please clarify.

Line 206

It was observed that…

Line 230

the values were 0.0008 and 0.2439 respectively.

Line 245

From the table, it showed the… Erase the words “From the table”

“…shown in Table 8, the R2 values…”

Line 254

The results have shown that it was feasible…

Line 260

…for the independent and the compatible models….

Line 261

 … it is shown that the independent

Line 262

Most of the models exhibited similar MRE values

Line 311

Our study showed the independent and compatible models not only can…

Line 314

the results are consistent with…

Line 315

the estimation accuracy overall for two models was all greater than 0.7. This result ->

The overall accuracy estimation for the two models was greater than 0.7. This result coincides with Xin’s….

Line 316

Citation for Tang’s result [?]

Line 320

Indicated that the …

Line 322

could not comply with the compatibility condition (the sum up of the biomass of each component equal to the total biomass).

Lines 325-334

This text in yellow background must be deleted because it is actually repeated in the lines 314-324

Line 337

…except for the foliage which had the lowest p values (BEFf = 0.61, BCEFf = 0.59). Our results were in accordance with the study of Schepaschenko et al [39],

Line 341

which is similar to the range

Line 347

The studies [45-47] indicated the values of BEF and BCEF…

Line 351

by using the BEF and BCEF that is provided by IPCC, illustrating

Line 357

could be obtained from remote sensing can quickly and easily calculate the BEF and BCEF of different

Line 359

the biomass in stands at large scales.

Line 368

basic model was calibrated considering the factors

Line 389

for the other components were all greater than

Line 390

…than other studies….

Comments on the Quality of English Language

The authors have changed many parts of the text and tried to improve the manuscript linguistically, but the manuscript still needs more linguistic improvement.

Author Response

Dear Reviewers and Editor,

we would like to extend my heartfelt appreciation to reviewers and editor for the dedicated efforts and valuable time spent on our manuscript entitled "A compatible estimation method for biomass factors based on allometric relationship: a case study on Pinus densata natural forest in Yunnan province of Southwest China" (forests-2716898). Please find my revisions in the "Revision, changes marked" and "Manuscript" files.

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I have received sufficient responses to each question posed during the earlier review rounds. The authors have made an impressive effort in taking into account all the suggestions I made in my revission. In its current state, I consider that the manuscript has reached the publishing level and can be accepted.

Author Response

Dear Reviewers and Editor,

we would like to extend my heartfelt appreciation to reviewers and editor for the dedicated efforts and valuable time spent on our manuscript entitled "A compatible estimation method for biomass factors based on allometric relationship: a case study on Pinus densata natural forest in Yunnan province of Southwest China" (forests-2716898). Please find my revisions in the "Revision, changes marked" and "Manuscript" files.

Response: Thank you very much for your thoughtful and thorough review of our manuscript. We appreciate the time and effort you have invested in providing constructive feedback throughout the review process.

We are delighted to hear that you have received sufficient responses to your questions and that our efforts to address your suggestions have been recognized. Your guidance has been instrumental in enhancing the quality of our manuscript.

We are honored that you consider the manuscript to have reached the publishing level and are willing to accept it in its current state. We are grateful for your support and look forward to the next steps in the publication process.

Once again, thank you for your valuable insights and guidance.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

My detailed comments have been answered, and appropriate corrections have been made in the text. Unfortunately, however, I must point out that this was done mechanically, without assessing the impact of these changes on the context of the entire article. In addition, my main comment referred to imprecise language that made it very difficult to understand the authors' intentions. I regret to say that this part was not done, and the changes made even reduced the clarity of the manuscript.
The text still needs to be cleaned up, to simplify the terms used and to use them according to their accepted meaning, for example, instead of "allometric growth relationships" it is better to use the term "allometric biomass functions". The titular term "compatible" in the literature is rather referred to as "additivity of biomass equations".
In addition, I did not find in the literature (even those that are cited) the names of the methods that were presented in the introduction.
In the case of methodology, a description of the measurement of tree biomass in the field was included instead of the unavailable literature. However, more important for the overall work is how these data were used in the calculations. What parameter estimation method was used to build the biomass formulas, was the additivity condition taken into account, how was the heteroskedasticity problem solved? I still can't find answers to these questions.

I still stand by my previous opinion that a thorough revision of the manuscript in terms of content and language is necessary.

Author Response

Dear Reviewers and Editor,

we would like to extend my heartfelt appreciation to reviewers and editor for the dedicated efforts and valuable time spent on our manuscript entitled "A compatible estimation method for biomass factors based on allometric relationship: a case study on Pinus densata natural forest in Yunnan province of Southwest China" (forests-2716898). Please find my revisions in the "Revision, changes marked" and "Manuscript" files.

Please see the attachment.

Author Response File: Author Response.pdf