Increasing Carbon Sequestration, Land-Use Efficiency, and Building Decarbonization with Short Rotation Eucalyptus

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article highlights the fast-growing Brazilian eucalyptus's much higher capacity to sequester carbon and quicker growth cycle as a sustainable substitute for conventional North American softwoods in buildings. According to a comparative analysis, eucalyptus can reduce atmospheric carbon by 2.7 to 4.6 times more effectively when used as a structural building material. To combat climate change, the study promotes using eucalyptus to improve land-use efficiency and decarbonize the built environment. There are a few comments related to this paper that the authors should consider:

1. line 4 to 8. Authors should follow the Journals template to write the author's name with their affiliations. 

2. Is it possible to cite the Abstract line number 14? 

3. The quality of the figures is low and should be improved.

4. The references should be written according to the journal's instructions.

There is an additional comment file attached 

 

Comments for author File: Comments.pdf

Author Response

Comment 1. Line 4 to 8. Authors should follow the Journals template to write the author's name with their affiliations.

Authors’ Response: The format used follows the journal’s template – no updates are needed.

 

Comment 2. Is it possible to cite the Abstract line number 14?

Authors’ Response: The Abstract has been reworded to remove the citation.

 

Comment 3. The quality of the figures is low and should be improved.

Authors’ Response: We increased the size of figures to make them clearer.

 

Comment 4. The references should be written according to the journal's instructions.

Authors’ Response: The references are written according to the submission template (i.e., numbered in order of appearance in the text and listed individually at the end of the manuscript; reference numbers are placed in square brackets and placed before the punctuation; the DOI for all references is included where available).

 

Reviewer 2 Report

Comments and Suggestions for Authors

I have annotated some suggestions/ corrections (comments) in the attached file. The MS needs a major revision. Also, use the headings and text in MS as per the sample chapter we provided earlier
Please revise the MS as per suggestions and respond to individual comments in a separate file.
Also, highlight the changes with different color or in track change mode in the revised MS

Comments for author File: Comments.pdf

Author Response

General Comments. I have annotated some suggestions/ corrections (comments) in the attached file. The MS needs a major revision. Also, use the headings and text in MS as per the sample chapter we provided earlier. Please revise the MS as per suggestions and respond to individual comments in a separate file. Also, highlight the changes with different color or in track change mode in the revised MS.

Authors’ Response: When the reviewer refers to the ‘sample chapter’ are they referring to the submission template? If so, the same section headers (i.e. Abstract, Introduction, Materials and Methods, Results, Discussion, and Conclusion) were used in the manuscript. Sub headers, which were permissible per the submission template’s instructions, were used to increase the structure and readability of the paper. The manuscript has been updated and responses to individual comments are included below. The word doc has track changes turned on such that the reviewer can easily identify the edits.

 

 

Comment 1. Kindly reword the sentence and delete the citation.

Authors’ Response: This change has been made.

 

Comment 2. Kindly add 1 line for aim/objective of the study.

Authors’ Response: Lines 15-16 were added.

 

Comment 3. How you compared, any parameter? please elaborate method in abstract section.

Authors’ Response: Lines 17-19 were updated to elaborate on the method.

 

Comment 4. Practical/economic/social implications would be interesting for the readers of MS.

Authors’ Response: In the Discussion section (sections 4.1 and 4.2), we discuss the global carbon impact and land-use efficiency impacts of increasing the use of Eucalyptus as a building material. While interesting, we view the other implications listed by the reviewer as out of scope for this paper.

 

 Comment 5. Avoid keywords which are in the title of MS.

Authors’ Response: Eucalyptus has been removed as a keyword.

 

Comment 6. Key words can be arranged in alphabetical order.

Authors’ Response: Keywords have been rearranged.

 

Comment 7. Kindly check for typo errors in whole MS.

Authors’ Response: This has been done. The journal’s reviewers/final editors will also double check for typos.

 

Comment 8. Kindly update the citation with recent literature in whole MS.

Authors’ Response: We have added additional literature references throughout the paper.

 

Comment 9. Kindly add 1 line for the rational of your hypothesis.

Authors’ Response: Lines 175-177 were updated to including the reasoning behind our hypothesis.

 

Comment 10. Try to start the sentence without citing table and figure. Please try to cite figure and table at the end of sentence.

Authors’ Response: This change has been made every time it appeared in the manuscript.

 

Comment 11. Discuss your significant results. No need to cite figure/table here in discussion section. Kindly discuss your findings and provide rational/citation in support of your findings.

Authors’ Response: Discussion sections have been reordered to pull up the most significant points to the first two sections. In addition, a short paragraph (lines 461-470) was added before Section 4.1 to further discuss the findings.

 

Comment 12. Add references in whole discussion section.

Authors’ Response: References have been added.

 

Comment 13. Significance of the study can be added here in 1 line.

Authors’ Response: Lines 705-708 were added.

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

The article, entitled ‘Enhancing Carbon Sequestration, Land Use Efficiency, and Building Decarbonisation with Short Rotation Eucalyptus’, aims to compare the use of fast-growing Brazilian eucalyptus with a group of commonly used North American softwoods (spruce, pine and fir) in a three-stage climate risk model.

The topic of the study is relevant to the need to reduce greenhouse gas emissions in building materials.

The authors point out that eucalyptus is underused as a climate-friendly building material.  Despite the fact that eucalyptus is the second most planted wood species, it is used first.

1. Introduction

The authors introduce the reader to the research problem by referring to the literature. However, the answer is missing: has similar research already been carried out on this topic? The authors refer to their article already published earlier.

What is missing at the end of this chapter is a presentation of the purpose of the research and a lack of research questions.

Literature review or theoretical background

Such a chapter is missing. A solid literature review is missing (there are only 31 in the bibliography).

2. Materials and Methods

 

In order to better understand the research process, I suggest creating a figure of the different stages of the work. The description in this section is too complicated. Information on data sources is missing. Similarly, the Figures have no stated sources.

 3. Results 

In this section, the authors present and describe individual figures without linking them to the research problem. What is missing is a more comprehensive description of this research and what is the result? 

Conclusion

Recommendations are lacking.

 

Author Response

Comment 1. Introduction – The authors introduce the reader to the research problem by referring to the literature. However, the answer is missing: has similar research already been carried out on this topic? The authors refer to their article already published earlier.

Authors’ Response: There has been research that investigates Eucalyptus as a building material from a physical/structural/performance standpoint (referenced in the paper), but there has not been a similar analysis (that we could find) that tries to quantify the carbon storage benefits of using Eucalyptus in buildings, making our study unique. As mentioned in lines 199-201, there is very little research available on long-rotation Eucalyptus plantations (10+ years instead of 4-7 years) used for the purpose of generating building material. We refer to our other paper as it makes the qualitative case for why Eucalyptus is an underutilized fiber in the built world, but we do not go deep into that research as it is not the main focus of this paper, which is to provide the quantitative carbon assessment for why Eucalyptus should be used as a building material (the other paper is meant to supplement this paper).

 

Comment 2. Introduction - What is missing at the end of this chapter is a presentation of the purpose of the research and a lack of research questions.

Authors’ Response: Lines 175-185 were added to summarize the purpose of the research.

 

Comment 3. Introduction - Literature review or theoretical background; Such a chapter is missing. A solid literature review is missing (there are only 31 in the bibliography).

Authors’ Response: As mentioned in our response to comment 1, a comprehensive literature review on the carbon benefits of Eucalyptus specifically for building products was not possible given the lack of literature in this space. Furthermore, the purpose of the study/paper was not to make the case of the suitability of Eucalyptus as a building material from a performance characteristics standpoint, but to assess the carbon storage potential. Because Eucalyptus plantations are mostly managed in short rotations (4-7 years) for pulp/paper/energy, there is very little available literature that would have been relevant for assessing plantations managed for construction products (harvest cycles of 10-15 years).

 

Comment 4. Materials and Methods - In order to better understand the research process, I suggest creating a figure of the different stages of the work. The description in this section is too complicated. Information on data sources is missing. Similarly, the Figures have no stated sources.

Authors’ Response: Figure 2 has been added to show the different stages of the work. Because the original model was developed prior to this work, we reference the original paper several times for the reader to access more detailed information about the underlying model development. Regarding data sources, additional wording was added to line 210 to clarify where the softwood data came from. Data for the Eucalyptus is described in lines 201-205 and 223-228. The figures have no stated sources because a description of the data sources was already provided in the Materials and Methods section (see line references).

 

 Comment 5. Results - In this section, the authors present and describe individual figures without linking them to the research problem. What is missing is a more comprehensive description of this research and what is the result?

Authors’ Response: Wording has been added throughout this section to more clearly describe the results and tie them back to the research objective.

 

Comment 6. Conclusions - Recommendations are lacking.

Authors’ Response: The submission template does not call for recommendations in the Conclusion. Recommendations for future research are included throughout the Discussion section.

Reviewer 4 Report

Comments and Suggestions for Authors

The article presents a study of decarbonization in the cultivation and use of eucalyptus in construction.

The Latin name is missing from the titl.

Abstract

The general scope of the research and the target of fast-growing Brazilian eucalyptus are indicated. The description is unnecessarily elaborate. The authors may reword and shorten it.

The results were not specified as their own.  The description of the rate of carbon removal by fast-growing eucalyptus is not supported.

The conclusion should include information from empirical studies.

Keywords

It is unnecessary to specify materials of organic origin, since the name eucalyptus is given

 Introduction

The first lines do not indicate what area is affected by temperature changes and whether the literature specifies these data.

The indicated indicators do not provide methods for calculating the carbon footprint for the indicated building materials including wood. What are these methods that confirm OC2 emissions?

The need for sustainable carbon sequestration including in new forests is rightly condemned. What are the possible environmental costs of such work?

Justification is given for the use of eucalyptus as a valuable species for construction. As recorded in line 97 we know of many other species in the world used in construction, why the lack of more information on properties? Other literature items for species in the Americas, Australia, Asia and Europe?

The company's own literature on bamboo as a plant of industrial importance is indicated - how does other literature compare the growth time of bamboo compared to eucalyptus?

 Material and methods

The methodology includes a model developed by the authors and presented in an earlier publication. Data were taken from the literature? How was the distribution of eucalyptus species in Brazil separated? What in Australia?

A description of production efficiency and the extent of processing, recycling , was obtained from a literature review? Only single literature sources were cited. What are the statistical data?

The description of the method for assessing decarbonization concerns for eucalyptus and other species is clear. However, the submission of a mathematical description of the assumptions presented was lacking.

 Results

The presentation of carbon accumulation rates for tree species should be described in the methodology. The results do not indicate the source of the data presented in the graphs.

The graphs are not very clear although they contain relevant information.

Can symbols be used to describe the species? This would make it easier to describe and read the results.

Presentation of results should be better described with mathematical evaluation of CO2 sequestration changes.

Ckl of carbon flow and other processes in the cultivation of eucalyptus are not related to the application for construction? What proportion of wood appears in construction?

Why only to coniferous wood US?

 

Discussion

The analysis of the carbon footprint of wood transportation is not referenced in the more numerous world literature (only literature entry 2 and 3). And the environmental costs of transport, type of transport, etc.? What does it look like on other continents? Europe and Asia?

Table 2 has no reference to data sources?

 

Linking the area of tree crops and CO@ sequestration is very important. The level of benefit from phasing out fossil resources is good. However, poorly supported by the literature.

The description of fast-growing species or limitations and future wood-based solutions has the same shortcoming (no reference to world literature).

Conclusions

Conclusions have been developed but do not include values of indicators to justify the direction of sustainable development.

Interesting publication, however, requires minor corrections and significant improvement in the review of available literature. An inadequate review of the world literature is indicated for such an important research topic.

Author Response

Comment 1. The Latin name is missing from the title.

Authors’ Response: The scientific genus name is used. ‘Eucalyptus’ is also the Latin name for the genus.

 

Comment 2. Abstract - The general scope of the research and the target of fast-growing Brazilian eucalyptus are indicated. The description is unnecessarily elaborate. The authors may reword and shorten it.

Authors’ Response: The Abstract was shortened slightly to try and be more concise.

 

Comment 3. Abstract - The results were not specified as their own. The description of the rate of carbon removal by fast-growing eucalyptus is not supported.

Authors’ Response: If the reviewer is referring to the ‘2.7x to 4.6x’ datapoints in the Abstract, these are not rates of carbon removal. They are Carbon Benefit Multiples (a novel comparative metric introduced in the analysis). Wording has been updated make this clearer.

 

Comment 4. Abstract - The conclusion should include information from empirical studies.

Authors’ Response: The results of this study (the CBMs and the conclusions that are drawn from them) are based on empirical studies. They rely on data that researchers have gathered through surveys, observations, and other forms of systematic data collection. Data-driven approaches were used to conduct this study/analysis, and conclusions are not drawn on theory or logic alone.

 

 Comment 5. Keywords - It is unnecessary to specify materials of organic origin, since the name eucalyptus is given.

Authors’ Response: Eucalyptus has been removed as a keyword.

 

Comment 6. Introduction - The first lines do not indicate what area is affected by temperature changes and whether the literature specifies these data.

Authors’ Response: What does the reviewer mean specifically when they write ‘what area’? All geographic areas of the Earth are affected by temperature change, and this has been well-documented across countless studies. Slight updates to wording of the first sentence have been made.

 

Comment 7. Introduction - The indicated indicators do not provide methods for calculating the carbon footprint for the indicated building materials including wood. What are these methods that confirm OC2 emissions?

Authors’ Response: The purpose of the study is to focus on carbon sequestration and storage, not net emissions. If we were to evaluate net emissions, we would certainly need to assess the carbon footprint associated with the manufacturing of building materials. Given this is not the focus, we only assess how much carbon is being stored in the various carbon pools, accounting to losses in carbon storage due to harvesting, manufacturing and EOL disposition. Note that all reported carbon metrics and graphs are in C not CO₂.

 

Comment 8. Introduction - The need for sustainable carbon sequestration including in new forests is rightly condemned. What are the possible environmental costs of such work?

Authors’ Response: Evaluating the environmental costs of establishing new forests is outside the scope of this work.

 

Comment 9. Introduction - Justification is given for the use of eucalyptus as a valuable species for construction. As recorded in line 97 we know of many other species in the world used in construction, why the lack of more information on properties? Other literature items for species in the Americas, Australia, Asia and Europe?

Authors’ Response: We wanted to keep the focus of this paper on the carbon benefits of Eucalyptus versus softwoods, which is why we chose not to go in depth on other properties. In lines 143-146, we mention another paper we have written that goes deeper into structural/performance characteristics of Eucalyptus that make it suitable for buildings, and the subsequent sentence (lines 146-148) briefly touches on this point and includes a reference that conducts a comprehensive assessment on the building-suitable properties of Eucalyptus. We conducted extensive research for biomass and carbon accumulation for Eucalyptus across the globe, but as mentioned in the paper, it was extremely difficult to find longitudinal plantation data for Eucalyptus with rotations longer than 10 years (because it is mostly harvested in 4-7-year rotations for pulp/paper/energy). Because of the limited available data, we were forced to only use examples from Australia and Brazil.

 

Comment 10. Introduction - The company's own literature on bamboo as a plant of industrial importance is indicated - how does other literature compare the growth time of bamboo compared to eucalyptus?

Authors’ Response: Comparing timber bamboo to Eucalyptus is not the focus of this study (nor do we reference any such prior research – the literature we reference in the paper is comparing timber bamboo to softwoods). We are conducting a similar study here comparing Eucalyptus to softwoods, not to timber bamboo. As such, we did not look for any other literature that compares the growth of timber bamboo to Eucalyptus.

 

Comment 11. Materials and Methods - The methodology includes a model developed by the authors and presented in an earlier publication. Data were taken from the literature? How was the distribution of eucalyptus species in Brazil separated? What in Australia?

Authors’ Response: Regarding data sources, additional wording was added to line 210 to clarify where the softwood data came from (this is the same data that was used in the earlier publication). Data for the Eucalyptus is described in lines 201-205 and 223-228. I’m not sure what the reviewer is asking when they write ‘was the distribution separated?’. The way the model was built, each individual species-location mix was entered as its own line item (i.e. there were five lines for BR-grandis, BR-urophylla, BR-saligna, BR-grandis x camaldulensis, and AU-grandis). Each of these separate datasets were used to create the graphs in Figures 4 and 5. When we get to Figure 6, we are now combining all Eucalyptus and taking an average of the five datasets.

 

Comment 12. Materials and Methods - A description of production efficiency and the extent of processing, recycling, was obtained from a literature review? Only single literature sources were cited. What are the statistical data?

Authors’ Response: The model used for this analysis was developed based off the USFS’s technical report which contains extremely comprehensive data tables. This is where we got the production efficiency data for the US softwoods. As stated in lines 199-201, equivalent data for Eucalyptus is simply not available because it is so uncommonly used to make building products. We therefore had to estimate/calculate the production efficiency data for Eucalyptus (we recognize this is a limitation in lines 583-585). For the HWP and EOL dispositions, we use a mix of the USFS data and another piece of literature (described in lines 252-259). Statistical data was not used in this analysis; a comment about this being a limitation of the study has been added in lines 587-589.

 

Comment 13. Materials and Methods - The description of the method for assessing decarbonization concerns for eucalyptus and other species is clear. However, the submission of a mathematical description of the assumptions presented was lacking.

Authors’ Response: An equation for how we calculate the NPV of carbon flows (which is used to calculate the CBMs) was added to line 282.

 

Comment 14. Results - The presentation of carbon accumulation rates for tree species should be described in the methodology. The results do not indicate the source of the data presented in the graphs.

Authors’ Response: The sources of the carbon accumulation data are in the author’s response to comment 11.

 

Comment 15. Results - The graphs are not very clear although they contain relevant information.

Authors’ Response: We increased the size of figures to make them clearer.

 

Comment 16. Results - Can symbols be used to describe the species? This would make it easier to describe and read the results.

Authors’ Response: We tested using symbols and did not think it was effective in communicating the information.

 

Comment 17. Results - Presentation of results should be better described with mathematical evaluation of CO2 sequestration changes.

Authors’ Response: We added additional text throughout the Results section to further describe the results and tie them back to the objective of the study.

 

Comment 18. Results - Ckl of carbon flow and other processes in the cultivation of eucalyptus are not related to the application for construction? What proportion of wood appears in construction?

Authors’ Response: I do not understand the first question in this comment (is the first word a typo or abbreviation?). Regarding the second question, is varies from geography to geography. In the US, approximately 89% of buildings are constructed with wood. However, in developing countries, the vast majority of construction involves cementitious materials.

 

Comment 19. Results - Why only to coniferous wood US?

Authors’ Response: Because the underlying model was built off the USFS report, and that report contained comprehensive data for the commonly used construction timbers, we did not see a reason to extend the analysis beyond the US. We have added lines 568-570 in the Limitations section to note the potential to include data sources from other regions.

 

Comment 20. Discussion - The analysis of the carbon footprint of wood transportation is not referenced in the more numerous world literature (only literature entry 2 and 3). And the environmental costs of transport, type of transport, etc.? What does it look like on other continents? Europe and Asia?

Authors’ Response: Because the analysis contained only US-based softwoods and mostly Brazilian-based Eucalyptus, we kept the transport comparison to only the US and Brazil. There are endless combinations of starting and ending destinations that can be used for this transport analysis, but we wanted to keep it simple and merely exemplary of the bigger discussion point rather than an in-depth analysis (which was not the main point of the paper).

 

Comment 21. Discussion - Table 2 has no reference to data sources?

Authors’ Response: Lines 521-522 tell the reader that the analysis used data from Simapro and ecoinvent (these were used to estimate the carbon impacts of transport). Rounded estimates using maps were used to come up with the transport distances, which can be done using any number of tools and therefore did not require a specific citation.

 

Comment 22. Discussion - Linking the area of tree crops and CO@ sequestration is very important. The level of benefit from phasing out fossil resources is good. However, poorly supported by the literature.

Authors’ Response: The main new data point that is introduced in this section (the total plantation area of Eucalyptus) is cited. The other data in this analysis builds off and leverages the same model/data used in the analysis above. If we the reviewer has suggestions for citations or literature to include, we welcome them.

 

Comment 23. Discussion - The description of fast-growing species or limitations and future wood-based solutions has the same shortcoming (no reference to world literature).

Authors’ Response: Another citation was added to section 4.4. Regarding limitations, these are specific to this study and therefore don’t require citations. If the reviewer could be more specific as to which lines within the Discussion need more literature support, that would be helpful.

 

Comment 24. Conclusions - Conclusions have been developed but do not include values of indicators to justify the direction of sustainable development.

Authors’ Response: The focus of this analysis was to compare the carbon storage benefit of Eucalyptus versus softwoods for building materials, and to a lesser extent, the land-use efficiency comparison of the two fibers. Other indicators for sustainable development (e.g. water usage, job creation, etc.) were outside the scope of this study.

 

Comment 25. Conclusions - Interesting publication, however, requires minor corrections and significant improvement in the review of available literature. An inadequate review of the world literature is indicated for such an important research topic.

Authors’ Response: Based on the revised manuscript and authors’ responses above, we appreciate further feedback/guidance from the reviewer on the topic of literature review.

Reviewer 5 Report

Comments and Suggestions for Authors

The authors conducted a large study evaluating the use of fast-growing tree species in construction to reduce carbon emissions. The article is of scientific interest and has practical significance for the field of construction. The only thing to note is that I would like to see more references to the literature used. This will allow the reader to better navigate the extensive information presented in the article. Below are some examples where the text requires explanatory links:

Lines 139-140: «Data for the three softwood species was drawn from six North American locations, for a total of seven distinct species-location combinations of wood» - link to the data source.

Lines 147-149: «Brazil has a recognized history of advanced breeding and silvicultural practices relative to Eucalyptus. Given the resulting speed and growth efficiency of Brazilian-grown Eucalyptus, rotation cycles of 10-12 years are common for sawlog feedstock» - link to the data source.

Lines 186-190: «The presence of climate system tipping points justifies incorporation of the time value discounting. In conventional finance, a discount rate is applied to each period of cashflows (or more generally, any forward benefit or cost). The higher the discount rate, the more near-term benefits are valued» - I think we need a reference to the general provisions of the theory for a more complete understanding of its application.

Author Response

Comment 1. The authors conducted a large study evaluating the use of fast-growing tree species in construction to reduce carbon emissions. The article is of scientific interest and has practical significance for the field of construction. The only thing to note is that I would like to see more references to the literature used. This will allow the reader to better navigate the extensive information presented in the article. Below are some examples where the text requires explanatory links:

Authors’ Response: We appreciate the reviewer’s feedback and guidance on where literature would strengthen our manuscript.

 

Comment 2. Lines 139-140: «Data for the three softwood species was drawn from six North American locations, for a total of seven distinct species-location combinations of wood» - link to the data source.

Authors’ Response: Text with a reference has been added to clarify where the data is coming from.

 

Comment 3. Lines 147-149: «Brazil has a recognized history of advanced breeding and silvicultural practices relative to Eucalyptus. Given the resulting speed and growth efficiency of Brazilian-grown Eucalyptus, rotation cycles of 10-12 years are common for sawlog feedstock» - link to the data source.

Authors’ Response: References have been added.

 

Comment 4. Lines 186-190: «The presence of climate system tipping points justifies incorporation of the time value discounting. In conventional finance, a discount rate is applied to each period of cashflows (or more generally, any forward benefit or cost). The higher the discount rate, the more near-term benefits are valued» - I think we need a reference to the general provisions of the theory for a more complete understanding of its application.

Authors’ Response: A reference to a generic overview of discount rates and NPV was added in addition to a reference to a study that uses economic discounting to assess climate effects.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All the comments have been incorporated.

Reviewer 3 Report

Comments and Suggestions for Authors

The article has been revised in accordance with the reviewer's suggestions. I make no comments.