Round 1

Reviewer 1 Report

Comments for author File: Comments.docx

Author Response

First of all, we thank to the anonymous reviewers for the detailed and constructive comments to our manuscript. We follow all the requests, and these are explained in attached file.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors and Editors,

 

The research results are original and significant, and the results justify and support the conclusions.

This paper assesses the standing-tree wood density of Norway spruce by micro drilling.

The investigation showed a new perspective on the correlation between wood density and micro drilling resistance on Norway spruce on a large number of samples.

The English language is understandable but needs some moderate corrections.

The paper is acceptable for publishing in the journal Forests after minor corrections.

 

The list below contains some specific questions and remarks about the paper.

 

Line 61. It would be better to call it a semi-destructive method. Although micro drilling does minor damage to standing trees or wood, it leaves a hole that is not from its natural growth. The non-destructive methods include sound waves, microwave measurements, or other non-body piercing methods. Consider naming it a semi-destructive method.

Line 70., 71. Unfortunately, I can not download the article (12), but this statement is intriguing. Suppose we know the mechanical properties decrease from oven dry state to approx fibre saturation point. In that case, the raw wood is expected to have a lower drilling resistance than, for example, wood at 12 % mc. Because of that, the resistograph scale cannot be the same for different moisture contents.

Line 83. Even the new drill needles bend and deviate from the straight line in dry wood beams, often following the less dense earlywood.

Line 139. In Table 1, you are missing the notes for abbreviations in the first, second and fourth columns. For example, what does the (V) in the fourth column stand for?

Line 146. Is forte a strong variant?

Line 152. Is the word approximately necessary?

Line 162. What was measured? Please specify.

Line 165. I believe you kept them in the refrigerator to avoid moisture loss.

Line 166. How did you measure wood density from Pressler samples? Please explain the process.

Line 178. What was the max drilling depth of the RESI?

Line 179. What was the feed and drill speed of RESI at the time of measurement? Was it the same for all trees?

Line 206. The Resistograph is the official product of Rinntech Inc., and it is a business opponent to IML. Maybe it would be better to write it with a small letter or to call it Resi, micro drilling machine or something like that.

Line 249. You are missing the moderate variant statistics for P2 in Table 2. You've mentioned in Line 143. there were three variants.

Line 256. The lowest average density control variant in Table 2 is 0,357 (P3).

Line 257. If you drilled the Pressler samples from all trees, you should probably notice (did you measure annual ring width?) the decrease in annual ring width from pith to bark. You can find in Sinković et al. (doi:10.15376/biores.16.4.6921-6932) an explanation of the correlation between annual tree ring width and wood density in coniferous trees.

Line 259. Repetitive sentence.

Line 284. See comment on Line 249.

Line 290. Can you explain such a statistical difference in drilling resistance considering almost no statistical difference between wood densities in Table 2.? What did you want to prove with these statistical tests?

Line 302. It is the other way around. The wood density was there before drilling, so the drilling resistance increases with density increasing.

Line 322. What is a gravimetric wood density? Is it related to moisture content?

Line 341. "stem decay"? Is this miswritten?

Line 404. How are all these previous investigations related to this research? This is not a discussion. These are facts from previous studies and, as such, could be mentioned in the Introduction. In Line 434. you have just repeated your results.

Line 439. The same comment as for the section before.

The whole Discussion is written as an Introduction. There is no direct discussion of the author's results with previous investigations. Therefore, this entire section should go to Introduction or be written appropriately.

Line 518. Ok, you can estimate wood quality through wood density which you proved correlates with micro drilling, but what kind of resistance are you estimating from micro drilling?

Line 521. It would be best not to refer to the previous sentence when starting with a new indentation. Instead, you have to write what "both" refers to.

Author Response

First of all, we thank to the anonymous reviewers for the detailed and constructive comments to our manuscript. We follow all the requests, and these are explained in attached file.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

General comments.

The authors have done a well in revising the manuscript and the introduction and discussion are good, with the exception of a couple of comments listed below.  I still have a concern about the statistical analysis approach used.  I have made some comments directly on the PDF for consideration

In regard to the statistical approach used my questions are as follows

1.       In Table 3 you present a pairwise comparison of the variants with site.  Why couldn’t you present the data using a bar chart along the lines below.  Here I have plotted the means and standard deviations from Tables 3 and 5.  A two way anova should allow you to comapra the means by Plot, Variant and Plot x Variant.  Based on the std dev. I would expect a Plot effect but no Variant effect on density.

2.       Following on from this in section 3.1.2 why separate out the Variants for analysis.  Why not combine all the data and look at the relationship between density and MDR across all samples.  This would greatly increase N.

I appreciate the work the authors have done in presenting the study but believe it would make a much better account if the analyses were clearer.

 

Specific comments

·         If I understand Figure 3 correctly, what you are doing is calculating the area-weighted mean Resi amplitude, or the amplitude you would expect from a cross-sectional disc.  Given that you are comparing with the basic density of an (non-area weighted) increment core, why not just use the pean Resi value from pith to Cambium.  We have found this to be highly correlated and is the actual basis of comparison needed. i.e. if you compared the Resi values and basic density of the “exact” same piece of wood, how well do they correlate? I assume the Resi traces were taken from the same aspect and close to whare the cores were taken?

·         Line 464-466: I disagree with this as a statement.  Numerous studies show strong correlations (r2 > 80%) between PD series drill traces and basic density.  Todoroki et al 2021 had an unusual method of calculating density from the Resi trace which I suspect reduced the variance explained.  Poor correlations have more to do with different instrument types and poor sampling (ie. not having a close correspondence between the wood being sampled and for basic density and by Resi. "Site effects" ultimately are expressed in affecting wood density.  In what way could "site effects" impact on the physical properties of the wood that affect resistance drilling?

Comments for author File: Comments.pdf

Author Response

First of all, we thank to the anonymous reviewers for the detailed and constructive comments to our manuscript. We follow all the requests, and these are explained in the attached file.

Author Response File: Author Response.docx