Assessment of Wooden Foundation Piles after 125 Years of Service

Round 1

Reviewer 1 Report

The article “Assessment of wooden foundation piles after 125 years of service - case study” by Humar et al. presents a solid investigation of waterlogged historic wood.

My main criticism about this article is related to the balance between the different sections: the article presents a very comprehensive Methodological section, but I found the Introduction and Results sections much more superficial. I explain more in my detailed comments below.

Additionally, the whole discussion would benefit greatly from data about the parameters of the soilin which the piles are buried. pH, conductivity, temperature cycles over the years, and other parameters have an impact in wood degradation and would help to interpret the results in a more holistic way. There are interesting examples of the importance of these parameters in the literature, for examples the publications about the wood analysis from the Biskupin site in Poland or the piles from La Marmotta, Italy.

More detailed comments follow:

Title: remove case study from the title, as it somehow underrates the value of the work.

Make the abbreviations explicit in the abstract

The introduction lacks a section regarding the scientific analysis of waterlogged wood. What are the methods and what are they useful for, so that the methodological approach chosen by the authors is justified in the light of literature data. Additionally, the literature review provided by the authors is quite limited, considering the number of research groups working on this topic.

Line 46: “In recent decades, a considerable number of wooden foundations across Europe have been severely damaged by a biological attack”: the biological attack has certainly not occurred in recent decades…why would that be? It is a phenomenon that occurs over centuries and not a recent development.

Line 62: bacteria also have specific classification and their decay patterns are not similar to soft rot. Please, expand on this based on the abundant literature on this topic. Also, I did not understand the comparison between the speed of bacterial decay and that of Basidiomycetes, as soft rot fungi are not Basidiomycetes.

Line 74: an error appears

Line 78: the water table??

Line 79: it would be relevant to expand on the location of the samples taken, the logic used to take the samples, the dimension of the samples and the number of samples taken.

Line 141: the term “cook” is probably not appropriate here. Maybe “heated”?

Line 177: “and the ring width and density are representative for respective region” I could not fully understand this sentence. Please, expand or clarify.

Line 185: I think the authors mean pile 2 and 3 here. Please, expand on this. What is the difference between pile 1, 2 and 3? Pile 3 appears in slightly better condition. Is there a reason for this?

Line 199: “The decay of the piles was also confirmed visually.” Please expand on this. What characteristics were observed?

Line 204: figure 2A and 2B are wrong and should refer to Figure 4. “Chemical analysis confirms other studies.” is confusing. Maybe “chemical analysis confirmed the results obtained by the other methods of investigation.

Line 206: saying that the lignin content increases is wrong, as additional lignin is not created in the wood. A relative increase in the percentage values referred to lignin content is a better way to express this concept. Also, degradation of cellulose and hemicellulose by soft rot has not been introduced yet in the results. So, at this stage in the manuscript, this result should be expressed as a relative increase in lignin due to general depletion of cellulose and hemicelluloses. I am sure the soft rot is not the only reason for such depletion. Additionally, Bronze Age piles are introduced here…it is not clear if these are from literature data related to the same site or something different. Please, expand on this point too. Finally, were the samples used for chemical analysis taken from which part of the pile? This should be used to discuss the results.

Line 212: hemicelluloses should be plural.

FTIR: in order to obtain a more correct representation of the differences between the two spectra, a normalization should be performed. One of the most accepted ways to do this is to normalize based on the lignin peak at 1505 cm-1. Such peak is notoriously less affected by any type of degradation in waterlogged wood. Change the figure accordingly and expand the discussion underlining this point.

Line 220: I think the moisture content should be discussed after the density and before the chemical analysis. Move this part before the discussion on lignin content by chemical analysis.

Line 228: There is no figure 5A

Line 253: the discussion on biomineralisation is interesting and it would be nice to expand on this a little bit more. How are S, Fe and Ca related to the biomineralisation? Which kind of bacteria do this?

The final paragraph on artificial mineralization is a little confusing. What is the point of bringing this up? How can it be expected that a few mineralized particles improve the mechanical properties of the wood? Please, clarify your point here.

Line 274: please use “relative increase in lignin content”

Conclusions: could the authors give an actual idea of the consolidation possibly needed for the piles and is it possible to estimate the lifetime of the piles if no consolidation is carried out?

Author Response

Dear editor and reviewers!

Thank you very much for your mail regarding the manuscript. Based on the respective suggestions, we have prepared revised the paper. We appreciate the efforts of the reviewers to improve the document. We have tried to consider the comments fully. Response to the respective comments is resolved below and highlighted in the text. In case of any issues or misunderstandings, do not hesitate to contact us.

 

Comment: The article “Assessment of wooden foundation piles after 125 years of service - case study” by Humar et al. presents a solid investigation of waterlogged historic wood.

My main criticism about this article is related to the balance between the different sections: the article presents a very comprehensive Methodological section, but I found the Introduction and Results sections much more superficial. I explain more in my detailed comments below.

Response: Dear reviewer. Thank you for your valuable comments. We appreciate the efforts. We have tried to consider all suggestions. We hope that you will find the manuscript considerably improved.

 

Comment: Additionally, the whole discussion would benefit greatly from data about the parameters of the soilin which the piles are buried. pH, conductivity, temperature cycles over the years, and other parameters have an impact in wood degradation and would help to interpret the results in a more holistic way. There are interesting examples of the importance of these parameters in the literature, for examples the publications about the wood analysis from the Biskupin site in Poland or the piles from La Marmotta, Italy.

Response: We have provided the pH values of the wood and the information about the soil type long term temperature variation… Introduction was updated with respective data.

 

More detailed comments follow:

Comment: Title: remove case study from the title, as it somehow underrates the value of the work.

Response: Comment was fully considered.

 

Comment: Make the abbreviations explicit in the abstract

Response: Comments were fully considered. Abbreviations are spelt out.

 

Comment: The introduction lacks a section regarding the scientific analysis of waterlogged wood. What are the methods and what are they useful for, so that the methodological approach chosen by the authors is justified in the light of literature data. Additionally, the literature review provided by the authors is quite limited, considering the number of research groups working on this topic.

Response: Comment was fully considered. Additional info related to waterlogged wood was provided.

 

Comment: Line 46: “In recent decades, a considerable number of wooden foundations across Europe have been severely damaged by a biological attack”: the biological attack has certainly not occurred in recent decades…why would that be? It is a phenomenon that occurs over centuries and not a recent development.

Response: Comment was fully considered. Sentence was changed.

 

Comment: Line 62: bacteria also have specific classification and their decay patterns are not similar to soft rot. Please, expand on this based on the abundant literature on this topic. Also, I did not understand the comparison between the speed of bacterial decay and that of Basidiomycetes, as soft rot fungi are not Basidiomycetes.

Response: Comment was fully considered. We have rewritten the sentence to avoid contradictions.

 

Comment: Line 74: an error appears

Response: Comment was fully considered.

 

Comment: Line 78: the water table??

Response: Comment was fully considered. Typo was corrected.

 

Comment: Line 79: it would be relevant to expand on the location of the samples taken, the logic used to take the samples, the dimension of the samples and the number of samples taken.

Response: Comment was fully considered. Additional details regarding the isolation of the sample were provided.

 

Comment: Line 141: the term “cook” is probably not appropriate here. Maybe “heated”?

Response: Comment was fully considered.

 

Comment: Line 177: “and the ring width and density are representative for respective region” I could not fully understand this sentence. Please, expand or clarify.

Response: Comment was fully considered. The sentence was revised.

 

Comment: Line 185: I think the authors mean pile 2 and 3 here. Please, expand on this. What is the difference between pile 1, 2 and 3? Pile 3 appears in slightly better condition. Is there a reason for this?

Response: Comment was fully considered. Additional explanation was provided.

 

Comment: Line 199: “The decay of the piles was also confirmed visually.” Please expand on this. What characteristics were observed?

Response: Comment was fully considered; the additional explanation was provided.

 

Comment: Line 204: figure 2A and 2B are wrong and should refer to Figure 4. “Chemical analysis confirms other studies.” is confusing. Maybe “chemical analysis confirmed the results obtained by the other methods of investigation.

Response: Response: Comment was fully considered; the text was changed accordingly.

 

Comment: Line 206: saying that the lignin content increases is wrong, as additional lignin is not created in the wood. A relative increase in the percentage values referred to lignin content is a better way to express this concept. Also, degradation of cellulose and hemicellulose by soft rot has not been introduced yet in the results. So, at this stage in the manuscript, this result should be expressed as a relative increase in lignin due to general depletion of cellulose and hemicelluloses. I am sure the soft rot is not the only reason for such depletion. Additionally, Bronze Age piles are introduced here…it is not clear if these are from literature data related to the same site or something different. Please, expand on this point too. Finally, were the samples used for chemical analysis taken from which part of the pile? This should be used to discuss the results.

Response: Comment was fully considered. Text was updated accordingly.

 

Comment: Line 212: hemicelluloses should be plural.

Response: Comment was fully considered

 

Comment: FTIR: in order to obtain a more correct representation of the differences between the two spectra, a normalisation should be performed. One of the most accepted ways to do this is to normalise based on the lignin peak at 1505 cm-1. Such peak is notoriously less affected by any type of degradation in waterlogged wood. Change the figure accordingly and expand the discussion underlining this point.

Response: Graph was normalised to lignin peak as suggested.

 

Comment: Line 220: I think the moisture content should be discussed after the density and before the chemical analysis. Move this part before the discussion on lignin content by chemical analysis.

Response: We have tried to move the moisture content part before the chemical analysis. We believe that we lost red line if we reorganise the manuscript in such away. Density Is related to chemical properties to a greater extent than with moisture content. Thus we kept the organisation of the manuscript as it is.  

 

Comment: Line 228: There is no figure 5A

Response: Comment was fully considered. Figure number was updated.

 

Comment: Line 253: the discussion on biomineralisation is interesting and it would be nice to expand on this a little bit more. How are S, Fe and Ca related to the biomineralisation? Which kind of bacteria do this?

Response: Additional information regarding mineralisation were provided. However, all processes associated with mineralisation are not clear.

 

Comment: The final paragraph on artificial mineralisation is a little confusing. What is the point of bringing this up? How can it be expected that a few mineralised particles improve the mechanical properties of the wood? Please, clarify your point here.

Response: Comment was fully considered; this paragraph was improved.

 

Comment: Line 274: please use “relative increase in lignin content”

Response: Comment was fully considered

 

Comment: Conclusions: could the authors give an actual idea of the consolidation possibly needed for the piles and is it possible to estimate the lifetime of the piles if no consolidation is carried out?

Response: Comment was considered. Additional explanation was provided at the end of the discussion, to keep the conclusions concise.

Reviewer 2 Report

The article reports on the assessment of historical wooden architectural components, and as such it fits in the topics of interest of Forests, potentially involving relevant sections of historical patrimony.

My first observation is: the authors should better stress the novelty of their contribution. Other studies on the degradation of wood buildings have been correctly cited, but the authors should highlight better what are the adds of their present contribution, besides applying valid assessment techniques to a relevant case study. For instance, the authors could explain better:

1) The potential application of their assessment routine to other case studies;

2) The relevance of the present case study and how much of the conclusions can be extended to similar historical heritage in the area and worldwide (also: state more precisely how many similar monuments are found in the area, etc.);

3) How their assessment can be preliminary to consolidation treatments, i.e. guiding or suggesting specific treatments whenever possible based on the characterization data.

My second observation involves pH: wood is intrinsically acidic, but upon degradation pH can go as low as 1-3, favoring the acid-catalyzed degradation of cellulose and consequently worsening the mechanical properties of wood, which is especially concerning in structural elements. The authors should monitor the pH of the samples as compared to the pine standards used in the article. Some protocols for measuring the pH of wood samples can be found in the literature (e.g. “Nanotechnology for Vasa wood de-acidification”, Macromolecular Symposia 238, 30-36, 2006; “Calcium hydroxide nanoparticles from solvothermal reaction for the deacidification of degraded waterlogged wood”, Journal of Colloid and Interface Science 473, 1-8, 2016), where strategies for conservation procedures are also discussed.

Author Response

Review 2

Dear editor and reviewers!

Thank you very much for your mail regarding the manuscript. Based on the respective suggestions, we have prepared revised the paper. We appreciate the efforts of the reviewers to improve the document. We have tried to consider the comments fully. Response to the respective comments is resolved below and highlighted in the text. In case of any issues or misunderstandings, do not hesitate to contact us.

Comment: The article reports on the assessment of historical wooden architectural components, and as such it fits in the topics of interest of Forests, potentially involving relevant sections of historical patrimony.

My first observation is: the authors should better stress the novelty of their contribution. Other studies on the degradation of wood buildings have been correctly cited, but the authors should highlight better what are the adds of their present contribution, besides applying valid assessment techniques to a relevant case study. For instance, the authors could explain better:

Response: Thank you for the comments. The novelty was highlighted, as indicated. We have highlighted that this is one of the few studies, where resistance drilling data were linked to the microscopy and chemical studies.

 

Comment: 1) The potential application of their assessment routine to other case studies;

Response: Comment was fully considered. The respective application was provided.

 

Comment: 2) The relevance of the present case study and how much of the conclusions can be extended to similar historical heritage in the area and worldwide (also: state more precisely how many similar monuments are found in the area, etc.);

Response: Number of the objects that are facing the same issues were estimated.

 

Comment: 3) How their assessment can be preliminary to consolidation treatments, i.e. guiding or suggesting specific treatments whenever possible based on the characterisation data.

Response: Comment was fully considered. Addtitional suggestions were provided.

 

Comment: My second observation involves pH: wood is intrinsically acidic, but upon degradation pH can go as low as 1-3, favoring the acid-catalysed degradation of cellulose and consequently worsening the mechanical properties of wood, which is especially concerning in structural elements. The authors should monitor the pH of the samples as compared to the pine standards used in the article. Some protocols for measuring the pH of wood samples can be found in the literature (e.g. “Nanotechnology for Vasa wood de-acidification”, Macromolecular Symposia 238, 30-36, 2006; “Calcium hydroxide nanoparticles from solvothermal reaction for the deacidification of degraded waterlogged wood”, Journal of Colloid and Interface Science 473, 1-8, 2016), where strategies for conservation procedures are also discussed.

Response: pH of wood was measured as suggested. Additional explanation was provided.

Round 2

Reviewer 1 Report

I would like to underline that when responding to reviewers’ comments, it is not sufficient to say “comment was fully considered”. I believe the journal also gives guidelines about this. Usually, a more accurate explanation is given, as well as the line number where the change is made and possibly, when sentences or paragraphs are added, they are copied in the response. In this way the reviewers can find the changes much more easily and they don’t have to necessarily read the entire article again.

Having said that, I think most comments have been addressed and the manuscript is improved. However, a few more things should be done before publishing the article:

Line 64: I don’t understand the difference between below-ground and in-ground and I don’t understand the use of the word “applications” in this context. Same for the following sentence. It sounds like the fungi or bacteria are applied. Also, in my initial comment, I specified that bacteria and fungi do not produce the same degradation features and are usually distinguishable. Please, revise this part and expand correctly.

Line 67: there are two interesting reviews that could be referenced here:

Analytical Instrumental Techniques to Study Archaeological Wood Degradation by Łucejko et al.

A review of analytical methods for assessing preservation in waterlogged archaeological wood and their application in practice by High et al.

Line 71: ling?

Line 75: GCMC?

Line 89: the error still appears

Line 196: it’s gleysol, not glaysol

Line 197: what is 5y4/1??

Line 196-202: this paragraph should be moved to section 2.1. Additionally, there is no need for the figure added (figure 2). Please, remove it. It is not part of your investigation.

Line 227: direct contact with what?

FTIR: you have performed the normalization, which makes the figure much better. But you haven’t said that the normalization was done. Please, add it in section 2.4

Paragraph starting at line 321: this paragraph belongs to the conclusions, as it summarises well the strong points of the article. I suggest it is slightly shortened and added to the conclusions, which are now a little short.

The English is quite poor in some areas, especially the ones added during the revision. In particular, the use of verbs of the past and present tenses is random and makes the reading more difficult. I suggest an English revision as well.

Author Response

See attachment, please...

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have greatly improved the manuscript

Author Response

Thank you for your positive response. We appreciate the efforts, and we are glad that you agree that paper is suitable for publication.