Properties and Depth-Related Changes in Moderately Fire-Affected Pedunculate Oak Wood

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overall, the manuscript addresses an interesting and relevant topic and presents a broad set of analytical methods; however, several methodological and interpretational aspects should be clarified and discussed in greater detail to improve the scientific quality and reproducibility of the study.

Abstract

• Terms such as “slightly higher,” “expected range,” and “potential utilization” should be more precisely defined or supported by statistical or practical context.
• The practical relevance and applicability of the findings should be emphasized more clearly.

Section 2.1 – Materials The section provides a general description of the sampling procedure and site conditions; however, additional information is required:

• Please clarify the meaning of “stem scorching” (line 80) and describe how this parameter was evaluated.
• Please provide information regarding the origin and characteristics of the control (unaffected) wood samples. If the data is taken from the literature, this is a significant limitation of the study.
• Additional information on tree characteristics should be included (e.g., trunk diameter, tree age, sampling height/from which part the samples were prepared)
• The manuscript states that samples were collected at 1 cm and 2 cm beneath the cambium (line 85); however, the dimensions of the mechanical and physical test specimens (e.g., 20 × 20 × 300 mm for bending tests) indicate that each specimen likely represented a broader radial zone rather than a discrete depth. The authors should clarify how the sampling positions were defined in relation to specimen dimensions and whether the reported depths correspond to the center, edge, or dominant portion of the sampled material. However stem scorching was 3-4 mm.
• The manuscript would benefit from the inclusion of a schematic figure or photographs illustrating the tested specimens.

Section 2.2  Please provide detailed information regarding specimen dimensions and the number of replicates used for individual analyses.

Section 2.3 Please specify the number of replicates used for individual analyses and clarify whether bending strength was evaluated in the radial or tangential direction.

The study would benefit from statistical comparison of the physical and mechanical properties.

Section 3.2 Please provide the moisture content of the specimens after conditioning.

 

Section 4 – Discussion

• Although several analytical methods were applied (FTIR, DSC, elemental analysis, mechanical testing), the manuscript does not fully exploit the potential for cross-interpretation among these datasets. A more integrated discussion would significantly strengthen the scientific contribution of the study.
• The manuscript repeatedly refers to “slight,” “minor,” or “relatively stable” changes. The authors should clarify whether the observed variations were statistically significant.
• The explanation for the stable or slightly increased compressive strength parallel to the grain appears somewhat speculative. Additional discussion is needed to distinguish between the effects of thermal drying, densification, and possible variability related to sample heterogeneity.
• The conclusions regarding limited heat penetration are plausible; however, they are presented rather categorically. Since no direct temperature measurements or microstructural analyses were performed, the authors should moderate these statements and acknowledge the indirect nature of the evidence.
• The manuscript would benefit from a broader comparison between hardwood and softwood responses to fire exposure.
• The statement that fire-affected oak wood “can still be utilized” should be supported by a clearer discussion of potential applications, limitations, and required quality assessment procedures.
• Since the trees were harvested approximately four months after the fire, the authors should discuss whether post-fire weathering may have influenced the measured properties.

Conclusions are formulated too categorically considering the limitations of the study, including the investigation of only one species, moderate fire severity, limited sampling depth and use a control data from literature.

 

Final remark
The manuscript would benefit from the inclusion of unaffected control samples collected from the same or nearby stand. Reliance solely on literature reference values may limit the robustness of the comparison due to the natural variability of wood properties and also restricts the possibility of direct statistical comparison between fire-affected and unaffected material. In its current form, the study appears closer to a case study or exploratory characterization of fire-affected oak wood rather than a fully controlled comparative investigation. The authors may therefore consider either acknowledging this limitation more explicitly or reframing the study accordingly.

Author Response

We would like to express our sincere gratitude for the careful review of our manuscript, the constructive comments, and the valuable suggestions. We greatly appreciate the time and effort you devoted to the review process, which has significantly helped us improve the quality, clarity, and scientific accuracy of the manuscript.

We have carefully considered all comments and incorporated them into the revised version of the manuscript. Detailed responses to the reviewers’ individual comments are provided in the attached response document.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the summary, I believe it's necessary to expand on the methods used in the study. For example, the sampling procedure for the fire resistance tests is unclear. It states that between 1 and 2 cm of the wood bark was used, which raises the question of whether roundwood or sawn timber with or without bark was used for the tests. This would clarify the issue of the effect of fire on juvenile versus mature wood. This should be clear from the summary onward because the effects and decomposition of the macromolecular elements of wood (cellulose, hemicellulose, lignin, and extractives) differ for each type of wood, and also for evaluating other properties such as physical and mechanical properties.

When referring to depth, are you referring to the depth of charring of the wood by the action of fire? If so, this should be specified in the text. I believe it is important for the authors to thoroughly justify this study, considering that the fire conditions affecting the wood were very superficial, with charring to a depth of less than 3 mm. Therefore, it is possible that the wood used for the tests—approximately 1 to 2 cm—did not undergo any thermal alteration. In that case, we would be evaluating the technological properties of the wood under natural conditions, not after a superficial forest fire.
It is unclear how the samples were taken. Perhaps it would be helpful to create a diagram or illustration representing the method and the portions of the log used for the tests.
It is important for the authors to consider that a graphical representation of the sample dimensions for all tests provides a visual starting point for the reader, offering more detailed information for wood preparation. In this case, I believe it is necessary to include diagrams and photographs of the equipment, sample, and tests, and not simply cite standards, as not all readers have access to them. One of the two main factors in wood that can influence its fire resistance are its chemical components. Therefore, it is important that the authors offer a more detailed explanation of the methodology used for the chemical analyses of the wood.
I consider it important to detail the objective of performing Fourier Transform Infrared Spectroscopy (FTIR), explaining which part of the wood was used and transformed into pellets, and for what purpose this test was carried out.
What was the reference material for the DSC analysis?
Why evaluate the effect of fire in the calorific value test of the bark? It is assumed that the fire primarily damaged the bark of the trees. I believe that the impact that should be evaluated is how the fire affected the properties of the wood and how deeply it penetrated it.
How can the authors ensure that the density of the wood in the internal part retained its original structure? Were density tests of the core performed? I believe it is necessary for the authors to discuss their results separately, based on the findings and by comparing them with similar studies. As they are currently presented, they appear to be conclusions of the work, which is not the case.

The conclusions align with the objectives of the work; however, it is necessary to include numerical values ​​that characterize the properties of the wood that were evaluated.

Comments on the Quality of English Language

The quality of language use is good.

Author Response

We would like to express our sincere gratitude for the careful review of our manuscript, the constructive comments, and the valuable suggestions. We greatly appreciate the time and effort you devoted to the review process, which has significantly helped us improve the quality, clarity, and scientific accuracy of the manuscript.

We have carefully considered all comments and incorporated them into the revised version of the manuscript. Detailed responses to the reviewers’ individual comments are provided in the attached response document.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript addresses an interesting topic concerning the influence of fire exposure on the properties of oak wood. The combination of physical, mechanical, chemical, FTIR, and DSC analyses provides a meaningful characterization of fire-affected wood. The overall experimental framework is meaningful, and the results generally follow known thermal degradation behavior of wood.

However, the current manuscript still contains several important issues to improve. In particular, some experimental details are insufficiently described, several interpretations appear to extend beyond the direct support of the presented data, and the Discussion section requires substantial restructuring and refinement.

Therefore, I recommend Major Revision before the manuscript can be considered for publication.

1. The key word“depth profiling” appears somewhat inappropriate in the current study because the sampling resolution is relatively coarse. It is recommended to remove or reconsider this keyword.
2. The final part of the Introduction should more clearly explain the scientific significance and novelty of the present study.
3. In Section 3.1 (Wood Density), samples were taken from three different positions. Please clarify which specific samples were used for density determination.
4. The same issue applies to Section 3.2 (Mechanical Properties). Please clearly explain which samples from the three positions were used for the mechanical tests.
5. Line 206–207: “The relatively high variability (coefficient of variation 36%) further indicates heterogeneous thermal exposure across samples.”Please clarify how the coefficient of variation was calculated.
6. Line 210–211: “This behavior is commonly associated with thermal drying and local densification of the cell wall structure, which can increase resistance to axial loading.” Please clarify whether this statement is supported by literature or experimental evidence. If so, corresponding references or supporting discussion should be provided.
7. In Table 2, the meaning of the decimal values presented in parentheses should be clearly explained in the manuscript.
8. Line 233–234: The authors compare the ash content with typical wood composition values. Please provide the corresponding reference values explicitly.
9. Line 236–237: “This increase suggests partial migration or concentration of low-molecular compounds in the thermally affected zone closer to the surface.” Please clarify whether this migration/concentration is directly caused by fire exposure and provide supporting evidence for this interpretation.
10. Line 250–252: Please clearly explain how the holocellulose content was calculated.
11. Line 287–288: In the FTIR analysis, please clarify which samples from the three regions were used for the measurements.
12. In Figure 1, the characteristic FTIR peaks discussed in the manuscript are not labeled clearly. The figure quality should be improved. In addition, please clarify whether spectral normalization was performed before comparing peak intensities.
13. In Figure 2, the origin and definition of the reference sample are unclear. Please clearly specify whether the reference wood corresponds to unaffected control material.
14. Discussion section:

(1)The Discussion section contains excessive repetition of the Results section and should be streamlined.

(2)Some interpretations currently go beyond what can be directly supported by the experimental data.

(3)The authors are encouraged to discuss the limitations of the study, such as the absence of an unaffected control group and the relatively low depth resolution of sampling.

(4)The relationship among chemical composition, FTIR, and DSC results should be discussed more systematically to improve the logical consistency between different analytical methods.

(5)Some literature-based descriptions could be reduced so that the Discussion focuses more directly on the findings of the present study.

(6)The Discussion section is currently too long and should be substantially condensed.

 

Comments for author File: Comments.pdf

Author Response

We would like to express our sincere gratitude for the careful review of our manuscript, the constructive comments, and the valuable suggestions. We greatly appreciate the time and effort you devoted to the review process, which has significantly helped us improve the quality, clarity, and scientific accuracy of the manuscript.

We have carefully considered all comments and incorporated them into the revised version of the manuscript. Detailed responses to the reviewers’ individual comments are provided in the attached response document.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors   Dear authors, comments have been incorporated into the manuscript and it can be published in this form.

Reviewer 3 Report

Comments and Suggestions for Authors

Agree to publication.