Variation in the Basic Density of the Tree Components of Gray Alder and Common Alder
Round 1
Reviewer 1 Report
Reviewer's comment on the manuscripts
"Variations in the basic density of the tree components of grey alder and common alder"
Dear Editor of Forest,
I am glad to review the manuscript "Variations in the basic density of the tree components of grey alder and common alder". The manuscript is interesting and significantly contributes to forestry's fundamental science. Unfortunately, the conclusion indicates that this research still needs to be completed because the authors did not state their proposed model. Please, the authors consider developing the model for determining the total biomass using the density of aboveground tree components and tree age and dimensions (DBH, stem length) for both the studied species.
After the authors complete the proposed model, I support publishing this manuscript in the forest. The detailed comments are below.
Best Regards,
Reviewer
1. Line 11-12: The subordinate phrase "To determine the BD of the belowground components" does not appear to be modifying the subject "alder stumps". Please consider rephrasing: Alder stumps were excavated to determine the BD of the belowground components.
2. Line 21-22: Please sort the keywords ascendingly based on the first alphabet.
3. Line 25: "Wood density" seem to disagree with the "fiber products" because some fiber products are not made from wood. Please consider removing wood: Density is the most important property affecting the quality of any solid wood or fiber product.
4. Line 27: "Density is the best single predictor of the mechanical properties of wood." The sentence needs to be clarified since density is not mechanical properties but physical properties. Please consider rewriting it for clarity: Density is the best single predictor to estimate the mechanical properties of wood.
5. Line 29: "To obtain reproducible measurements" is a dangling modifier. Consider rephrasing: Wood density is widely calculated as the proportion of the oven-dry mass to the corresponding volume of fresh wood to obtain reproducible measurements because these indicators are constant; this is referred to as wood's basic density (BD).
6. Line 39-43: The word is long and hard to read. Please consider splitting it. However, this procedure excludes non-merchantable components, such as tree tops, branches, bark, stumps, and belowground components. The forest inventory usually documents growing stock, net annual increment, or wood removals in m3 of merchantable volume.
7. Line 44: Please consider replacing "wider implementation" with "broader implementation".
8. Line 45: "aboveground and belowground biomass" seems to be missing the article "the aboveground and belowground biomass"
9. Line 46-48: The sentence is hard to read. Please consider splitting it: Terrestrial laser scanning or X-ray computed tomography can be applied to directly measure the above and belowground volume of trees [9, 10]. At the same time, precise values for BD are required to convert the volumes of tree components into biomass.
10. Line 49: "The use of" seems wordy. Please consider replacing it with "applying" or "using".
11. Line 51, Line 350: "strong genetic control" is confusing because of the dual meanings, i.e., (1) The strong genetic controls the wood density" or (2) "The genetic strongly controls the wood density". Please consider rephrasing: "the genetic's strong control" or "the strong genetic's control".
12. Line 52: "sound knot-free wood" also has a dual meaning: "the wood is sound" or the "knot is sound". Please consider replacing it with "knot-free sound wood" or "clear wood". The term "clear wood" is also well-known to state the wood which does not have any defects, such as knots, the slope of grain, split, check, birds peck, and pitch pocket.
13. Line 85: "the climate change mitigation potential of forests" Please consider rewriting it for clarity: "forests' climate change mitigation potential"
14. Line 86: "To gain a better understanding of biomass…". Please consider rewriting it: To understand biomass better…
15. Line 91-92: "The wood density of common alder increases slightly with the age of the tree". Please explain the phrase "the age of the tree". Which one, the outer wood and the inner one, is older? Is the younger wood denser than the older one?
16. Line 95-96: "At present, there is no indication that radial variation in the density of stem wood and tree components for both these alder species has been studied elsewhere." This sentence is potentially an overconfident claim. Have the authors read all scholarly articles? Please consider making a milder statement: The authors have not found any indication that radial variation in the density of stem wood and tree components for both these alder species has been studied elsewhere.
17. Line 100: Please consider replacing the word "wider" with "broader".
18. Line 126: "Stump height was used to divide the trees into above and belowground components." There are 27 and 28 belowground component investigation, while 81 and 81 above ground components (Table 1). Did the author cut 109 Grey Alder and 108 Common Alder? If the above- and belowground investigations come from the same trees, please explain why some bellow ground components are missing.
19. Line 166: How confident did the author state that the 24 water-immersed wood specimens did not absorb the water while taking measurements? Did the authors measure the water volume in the apparatus before and after every test? Did the water's volume in the apparatus decrease after the test? Please explain it.
20. Line 259: "(ρ = -0.712 – -0.794)". Please consider rewriting min – max value: "(ρ = -0.794 – -0.712)".
21. Line 351-353: This statement indicates that this research still needs to be completed because the authors do not state their proposed model. Please consider developing the model for determining the total biomass using the density of aboveground tree components and tree age and dimensions (DBH, stem length) for both the studied species.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
I have reviewed the manuscript titled “Variations in the basic density of the tree components of grey alder and common alder” thoroughly.
General
1. Figures are very poor.
Abstract
1. Please revise the abstract; first write the background of the study, then your aims, methodology, results highlights, conclusion and at the end future recommendations.
Methods
Study sites and sampling
1. Please provide map of the study area along with the position/site of data collection.
2. For each tree species, 81 sample trees were harvested to investigate the density of aboveground components as well the radial and longitudinal variation of BD within the tree stems. What is the reason that for each tree species, 81 sample trees were harvested to investigate the density? Why not more?
3. Sampling was performed during the dormant period when trees were leafless. What is the reason behind this?
4. When each sample tree was felled, subjectively selected average-size living branches from the lower (B1), middle (B2), and upper (B3) sections of the living crown were sampled. Why only these parts?
5. . Stems shorter than 20 m were divided into 1 m sections while those longer than 20 m were divided into 2 m sections. Which method you have used for dividing the stem? Please explain in detail.
6. The belowground components of 28 grey alder and 27 common alder trees were used to investigate stump and root density. Why not equal to the sample of the stem? Dose it safe from conservation point of view?
Laboratory analyses
1. All wood samples were transferred to the laboratory and stored in a refrigerator until further processing. Explain this step in detail that how you sorted the samples and at which temperature?
2. How you determined the BD of each wood specimen through Precisa XB 220A. Please explain in detail.
3. Before starting this process, all the specimens were immersed in water for 24 h to avoid absorption of water while taking measurements. The oven-dry weight of specimens was obtained by drying them at 103–105°C until a constant weight was achieved, scaling them immediately after being removed from the drying oven. The BD was calculated as the ratio between the dry mass and fresh wood volume of a wood or bark specimen. Please provide citation/reference for this technique or if it is your own developed technique then explain it in more detail.
RESULTS
1. The BD of branches was higher than that of stems in both species. What is the possible reason? Please support your result with the help of available literature.
2. Moreover, for both species, branches in the lower part of the crown had a significantly higher density than those sampled in the middle or upper part. What is the possible reason? Please support your result with the help of available literature.
3. For common alder, the stump BD appeared to be significantly lower than that of the branches; no such differences were detected for grey alder. What is the possible reason? Please support your result with the help of available literature.
4. The belowground biomass of alders had lower BD than aboveground components. What is the possible reason? Please support your result with the help of available literature.
5. The coarse root density was higher than small root density and samples taken at the smaller ends (diameter over 2 cm) had significantly lower density when compared to samples taken at the middle and thickest end. What is the possible reason? Please support your result with the help of available literature.
6. Although the average bark density of both alder species was higher than that of wood, however, an axial variation was observed along the stem for both species. What is the possible reason? Please support your result with the help of available literature.
7. As shown in Figure 3, the bark BD of common alder was higher than that of wood in the upper part of the stem while the densities of both components are similar at the base and in the middle portion of the stem. The opposite tendency was observed for grey alders, the bark of which was denser than wood at the base of the stem. The average bark density was 414.23±5.31 kg m-3 for common alder and 403.25±3.80 kg m-3 for grey alder; however, the significance of the difference could not be proved statistically. What is the possible reason? Please support your result with the help of available literature.
8. Unlike aboveground components, the density of all belowground components was significantly higher for grey alder than common alder. What is the possible reason? Please support your result with the help of available literature.
9. The dominant trend for within-stem density variation for both alder species was that BD was lower at the base of the stem and increased toward the top. What is the possible reason? Please support your result with the help of available literature.
10. However, according to our data, it is evident that grey alder has more homogenous wood than common alder because BD variation across the stem was less pronounced for this tree species. What is the possible reason? Please support your result with the help of available literature.
11. The correlation between tree attributes, bark and branch BD was substantially stronger (ρ ranging from 0.365 to 0.585). What is the possible reason? Please support your result with the help of available literature.
12. Relationships between tree attributes, stem wood, and total stem BD were stronger for common alder than for grey alder (ρ = 0.506 –0.669). What is the possible reason? Please support your result with the help of available literature.
13. Nevertheless, a strong negative relationship was found between tree attributes and bark BD (ρ = -0.712 – -0.794). What is the possible reason? Please support your result with the help of available literature.
14. Age, DBH, and H showed a positive relationship with average coarse root BD for common alder; however, no correlation between BD of belowground components with tree attributes was found for grey alder. What is the possible reason? Please support your result with the help of available literature.
Discussion
1. Improve the discussion by comparing your results with the available literature and support your results by giving evidence from the available literature. Throughout the discussion, you didn’t give single piece of evidence from the literature, instead just provided your own ideas for supporting the results.
Conclusion
1. Please rewrite the conclusion which includes highlights of your results.
2. What are the recommendations for the future?
3. What are the benefits of this study?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear Editor of Forests
Thank you for the opportunity to review the manuscript Variations in the basic density of the tree components of gray alder and common alder. The authors have responded well to my comments. I have no fundamental objection anymore; thus, I support publishing this manuscript.
Best Regards,
Reviewer
Author Response
Thank you very much for your support!
Reviewer 2 Report
Dear Editor
The authors have revised the manuscript in a good way according to the suggestions.
Author Response
Thank you very much for your support!
