Estimating Small-Scale Forest Carbon Sequestration and Storage: i-Tree Eco Model Improved Application

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

Relevant work but the draft is like a "draft0" and should meet the journal standards and author guidelines before submission. Looks like a technical report turned research paper and there's a lot of contents that need polishing formatting-wise, results and interpretation, and discussions. 

37.19tC/ha vs  5.97 tC·ha-1·yr-1 format
350m should be 350 m
what do you mean by "traditional InVEST"? And Traditional IPCC?
Introduction too shallow. 
Can you review the literature who already implemented i-Tree or similar to such and tackeld same problem of small-area measurements and what's the added value of your research vs them?
Do you mean by application-prone in line 75?
See you have bunch of models adn references in Table 1 and 2, contextualize them further in the Introduction
2.2 Can you instead craete a timeline of i-Tree and its development/progress so readers can grasp the model better
Lines 184-187 format the equation numbers!
Table 3 makes me dizzy 
Table 5 column 2 first 3 rows what /who are they? add reference!
Table 6 reformat!
Lines 285-286 makes me want to reject your paper
Figure 2 spatial resolution? LULC map reference you did not mention in the methods
FIgure 4 what kidn of lazy binning is this?? at least use equal intervals
Figure 5 can you use gigagrams instead?
Append Figure 8 and Figures 9-100 which are haphazardly produced
Figure A1 could go in the main text
Check journal format.. Discussion always separate wiht COnclusion
Line 684 how about with remote sensing derived products like CCI Biomass? worth trying!
Can't find explanations of your results why your estimates e.g. FIgure 5 always lower than IPCC except for 1 region??  I was expecting more of these comparisons also vs. InVEST but instead I see many maps that don't tell a lot 
Better FIg3 and Fig4 side by side!
Fig 6 and 7 too and same color-coding/legend!

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

 

This paper employs a tree allometric growth model—the i-Tree Eco model, which is relatively new in the application of the citywide carbon sinks estimation and can effectively differentiate between high and low gradients of forest carbon sinks, aiming to complement traditional carbon sink models in terms of improving accuracy, spatial resolution and applicability.

The subject addressed in this article is worthy of investigation. The organization of the manuscript is very satisfactory The Literature Review is good.

I have some suggestions to the authors only in order to improve the quality of the manuscript.

In Methodology Chapter it is better to add a flowchart figure explaining about the overall method of the study.

In some figures (for example Figure 11) there is text overlapping on the XX axis. Review this situation throughout the article.

In the list of References the authors must include all authors and not just et al. (for example: Vanhala, P., et al.)

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

INclude accessibility of the i-Tree model how to access it even in the abstract (link).. Double check / proofread several times more

Update Figure 1 what about >2020. This means it's outdated

Can you sikmplify Figure 2

Be consistent with your decimal places

I don't understand Figures 11-13 and why graph looks noisy and without trends

Can you include FigureA1 as a main figure? or in a graphical abstract?

Table 1 not formatted well

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

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.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comments:

The presented article is the result of an extensive study that employs modern evaluation methods for carbon sequestration and storage. It is particularly important as it analyzes this aspect in the context of a specific city—an area that, as the authors highlight, has been less explored by other researchers so far. However, the paper requires significant revisions to enhance its clarity, coherence, methodological rigor, and overall presentation.

Sugestions for revision:

1. Presentation mode:

• Figures and tables should be better integrated into the text. The captions should clearly describe the content and significance of each figure and table.

• Use different keywords than those in the article title.

2. Methodology improvements:

• The indicator conversion process needs more justification, particularly regarding the assumptions made when aligning the Tai’an Forest Resources Inventory database with i-Tree Eco’s requirements.
• The paper should provide more details about the validation process, ensuring that the assumptions and transformations made do not introduce biases.

• In the methods section, you did not mention the statistics used, e.g., regressions, etc.

3. Results and interpretation:

• The carbon sequestration and storage estimates need a more in-depth discussion of potential uncertainties and limitations in the methodology.
• More emphasis should be placed on discussing the implications of the findings for policymakers and urban planners.

• Add information about the population of Tai'an City.
• In the figures, when the cursor is placed over them, some text appears in Chinese.

4. References and citations:

• Some references lack proper formatting. Ensure consistency in citation styles. Examples:

4.1. Missing details in citations:

"Piao et al. 's study on carbon sinks in Shandong [66]."
The apostrophe usage is incorrect.

The reference is vague and does not provide complete details such as the year or title.

4.2. Inconsistent use of journal titles and formatting:

"Cimburova, Barton. 2020. “Geospatial Analytics for Urban Forestry.” In Environmental Studies, 34(3): 145-157."
Author names should follow a consistent format (e.g., first initials followed by last name).

5. Language and grammar:

The manuscript contains grammatical errors and awkward phrasing. A thorough language check is necessary. Examples:

5.1. Phrasing:

Original:
"Methods based on which high–low gradients of forest carbon sinks within small-scale areas can be accurately distinguished have not been established."
Suggested revision:
"Methods that can accurately distinguish high–low gradients of forest carbon sinks within small-scale areas have not yet been established."

5.2. Redundancy and wordiness:

Original:
"Between the two major types of carbon sinks, ecosystem carbon sinks are safer, stabler, and more efficient compared to artificial carbon sinks."
Suggested revision:
"Among the two major types of carbon sinks, ecosystem carbon sinks are safer, more stable, and more efficient than artificial ones."

5.3. Improper use of prepositions:

Original:
"Compared with the traditional IPCC method, the i-Tree Eco provided a better accuracy and timeliness for small-scale carbon sequestration measurements."
Suggested revision:
"Compared to the traditional IPCC method, the i-Tree Eco model provided greater accuracy and timeliness in small-scale carbon sequestration measurements."

5.4. Subject-verb agreement issues:

Original:
"The estimation results of the i-Tree eco covered all forested land."
Suggested revision:
"The estimation results of the i-Tree Eco model covered all forested land."

5.5. Unclear sentence structure:

Original:
"However, only few carbon sink measurement methods are suitable for small-scale research (e.g., city region scale)."
Suggested revision:
"However, only a few carbon sink measurement methods are suitable for small-scale research, such as at the city-region scale."

Conclusion:

The article is of interest to the scientific field and may be published in this prestigious journal; however, I believe it requires some improvements, as mentioned above. In conclusion, I consider it suitable for publication after a major revision.

 

Comments on the Quality of English Language

could be improved

Reviewer 2 Report

Comments and Suggestions for Authors

Comments can be found in the attachment. 

Comments for author File: Comments.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors of this manuscript appear to be attempting to use i-Tree Eco and forest inventory data as a biomass variable for an IPCC carbon accounting/sequestration model. The idea is interesting although it is not new to combine forest inventory data with i-Tree Eco for biomass estimation. I have some concerns about the presentation of the paper and the results found. I will list those below:

Abstract

Lines 14-19: Using iTree Eco and inventory data is not a new concept/idea. Also think some quantification is needed related to results of carbon sinks/sequestration.

Introduction

Line 32: What is an artificial carbon sink? Do the authors simply mean non-vegetative?

Line 54: "new tree allometric growth model..." iTree is approximately 20 years old. What is meant by "new"?

Lines 63-63: This methodology is less labor intensive compared to what? If accounting is needed for accreditation/contracting purposes, generality may not be worthwhile.

Literature Review

Table 1: Center text in Advantage column. Can the entire table be on one page?

Methodology

Lines 164-166: The 0.5 conversion is an average dry-weight biomass conversion for carbon content. If species-level data are collected, is it possible or feasible to use species-specific conversions?

Line 170: "...into a complete inventory." Does this mean 100% inventory was completed? All the trees were measured? Or is this a setting for plot-level vs tree-level inventory? Not clear in this sentence.

Line 183: remove "the" as the third word..."In addition, i-Tree..."

Table 3: Is this "disaster level" for the attributes listed - pests/disease, fire, climate damage?

Lines 223-225: Not clear what this is saying (the appendix did not help). Think it is beneficial to explain here as this is used, for some reason, as a comparison later. Is this the acreage in Tai'an for each land cover or is this an estimate (Table 6)? If the area is "built up" what carbon storage is going on? What is the resolution of the LC data used? Lastly, I think this can be removed as it does not really add anything to the focus of the results later.

Section 3.1.3: How is the IPCC forest carbon data being mapped? Interpolation?

Figure 1: This is a large area. The citations in Table 3 are urban centers. Is that part of the justification? The authors are trying to apply the methods to a larger area?

Line 286: "...41,031 items of valid data..." Are these items individual trees or inventory plots? This needs to be explained a little more.

Lines 292-293: Move this sentence to end of previous paragraph.

Results

Generally: Why not use square meters or hectares (what a hm2 is)?

Line 301: "...covered the entire city." Does this exclude areas that have no vegetation?

Figure 2: Are that many significant figures needed?

Line 309: the number 6897473.91 t needs commas. There are other places where commas are missing. Please address all those for consistency.

Figure 3-7: Repeat - too many significant figures. One/two decimal places is plenty.

Line 320: 195mX195m - how was this resolution obtained?

Lines 337-343: Are these two different methods or the same InVEST looking two time periods? One shows the are as a source of carbon then very large increase in sequestration in two years. How could this be the case unless there was some very great effort to afforest/reforest? And even then, that is tough to explain in two years.

Section 4.2: How do the authors justify comparing the 350 meter resolution data with 195 meter resolution data?

Lines 365-367: This is related to the comment above but further here, one method is inventory-based (allometric calculation) and the other is based on land-cover and LULC.

Section 4.3: These are new methods? The sampling bands would be better there I think.

Figures 8-12: Are there units for the axes?

Line 410: I'm not sure "innovatively" is the right word. Again, others have used inventory data with i-Tree Eco.

Table 7: There's a regression model now. Is this in the methodology?

Lines 464-465: What is meant by "should consistently over- or under-estimate..."? If it is underestimated, it is consistently done and if it overestimates, it is consistently done? Or will this vary with forest type/biomass (the x in the regression model) that is calculated based on changes in tree species, size, etc.?

Discussion and Conclusion

Lines 474-480: How does forested area compare between these locations? If the present study area is larger, with a larger percentage of the area forested, it may explain these differences? This is also only comparable if the methods are. Might be better to use the inventory data to calculate the carbon content and compare that to the model output - in terms of bias?

Line 493: "dieback..." Crown dieback is an ocular estimate so the values determined using the inventory data may be valid if all possible crown losses are covered.