Individual Tree Diameter and Height Growth Models for 30 Tree Species in Mixed-Species and Uneven-Aged Forests of Mexico

Round 1

Reviewer 1 Report

I appreciate very much reading the manuscript. The authors present valuable research about the development of individual tree diameter and height growth models for a large tree species in natural forests of Mexico. I have some comments to the authors.

1. L167. The authors should explain how did they evaluate the stand dominant height in mixed stands.
2. The authors present Eq 2 and 3 as the best candidate model formulations. Did those models performed as the best for each of the species? Or did they performed the best, in general, among the ones tested? Please clarify.
   (For instance, it seems that the variable H0 does not seem to be statistically significant for most of the strawberries species - Table 3, or the variable BAL for some of the Quercus species - Table 4; see also L296-297).
   As the effect of Ho is not consistent across species, why did the authors use the same formulation (base model) for all the species?
3. Table 3 and 4: the units of the RMSE statistic should be provided.

Author Response

Dear Reviewer,

We have revised the Manuscript: forests-750803 “Individual tree diameter and height growth models for 30 tree species in natural forests of Mexico” taking full account of your comments.

Please find attached our responses to your suggestions and the corresponding changes that we have made to the manuscript. All the changes incorporated in the text have been highlighted. Some suggestions that involved the deletion of pieces of text have not been indicated.

Yours Faithfully,

Dr. José Javier Corral Rivas

(Corresponding author)

Author Response File: Author Response.pdf

Reviewer 2 Report

General opinion

This work is based upon a large data set, collected in the Sierra Madre mountains in Mexico. This is a region characterized by a rich flora of woody plants, with many tree species that are actually endemic. Forests of this region have been relatively poorly studied until recently. So the information about these forests and these tree species is very valuable in itself. This is the strong point of the manuscript.

The statistical methods used for developing growth equations are new, sophisticated and applied in a rigorous way. The text is well supported by the relevant contemporary literature. However, one important source is definitely missing: "Forest Dynamics, Growth and Yield” by H. Pretzsch (2009).

That said, I need to admit that the manuscript is only marginally focused upon the characteristics of these forests and these tree species. The main focus of the authors is constructing growth models for 30 most common tree species of that region. They did it and proved that their models explain sometimes even over 90% of variation in growth rates. Much of the "results" section is concentrated on presenting the parameters of the growth equations and the goodness of fit. It looks like an exercise in pure statistics, without paying much attention to what these numbers actually represent.

Discussion is the weakest part of this manuscript. Many of the interpretations of the results are trivial, like the one that tree growth is a function of tree size at the time of the first measurement. Such findings have been already described in numerous textbooks. Other interpretations are far reaching. For example, suggesting, that competitions plays a minor role in growth of some species, or that environmental factors are not important for growth rates of the others. The foundations for these bold statements are very fragile.

Specific remarks

• Line 30: "prevents" is not a proper term there
• Line 33: "strawberry species"; you need to mention, that it means the genus Arbutus; otherwise the readers will be confused
• line 55: "tree competition" is not an attribute of the tree; maybe "tree competitive status" or something like that
• lines 60-65: you repeat almost the same in two consecutive questions
• Lines 72-74; an awkward sentence, should be re-written
• line 84: rather "ecosystem services"
• lines 86-87: uneven-aged are forest stands, not forest ecosystems
• Table 1: it is surprising, that H_o increased by 2.1 m over five years. Do you consider it therefore a reliable characteristics of site conditions? You need to comment on that in discussion
• Line 279: "widely believed" is an understatement. There are strong scientific foundations for that relationship
• Lines 288-292: old and large trees are scarce in most forests; the size of your sample was not big enough to find them.
• Lines 337-343: this is trivial, could be written without conducting such a massive study as you did
• Lines 344-347: did you analyze the vertical stratification of trees within sample plots? If yes, where are the results? If not, these are speculations
• Lines 378-381: this is an overstatement. Please provide some examples, how the growth equations could help forest managers.
• Lines 446 and 540: the paper by Aakala et al. (2013) is listed twice, under two different numbers

Author Response

Dear Reviewer,

We have revised the Manuscript: forests-750803 “Individual tree diameter and height growth models for 30 tree species in natural forests of Mexico” taking full account of your comments.

Please find attached our responses to your suggestions and the corresponding changes that we have made to the manuscript. All the changes incorporated in the text have been highlighted. Some suggestions that involved the deletion of pieces of text have not been indicated.

Yours Faithfully,

Dr. José Javier Corral Rivas

(Corresponding author)

Author Response File: Author Response.pdf

Reviewer 3 Report

The study analyzes growth of individual trees in mixed-species, uneven-aged forests in Mexico. The strength of the paper is developing results for important knowledge gap.  The weakness of the paper was unclear hypotheses.  Overall, the paper was well written and covered an important topic in forestry and forest ecology.

Novelty, Interest, Importance

---The justification for the study was explained and cited.  This type of analysis is rare, especially for the forest type. The work is important to share widely.

Organization

---The paper was well organized and ideas explained.

Paper summary (Title, Abstract, Keywords)

---I suggest the title to be revised to include mixed-species and uneven-aged – which are too important knowledge gaps addressed with this study.  If this suggestion is used, then the keywords should be revised accordingly.

Introduction

---The introduction was thorough, except hypotheses were missing.  The authors should state the general hypotheses based on the literature presented in the introduction.  This is important to raising the scientific rigor of the paper.

Methods

---The methods were detailed sufficiently and seemed appropriate, but this was not an area of analytical expertise for me. The methods could be edited in context to hypotheses.

Results

---The results were presented sufficiently.  I appreciated the interpretative phrases (e.g., LL213-214 “indicating tha(n)t dbh….”.  (“Than” is a typo for “that”.) The results could be edited in context to hypotheses.

Discussion

---The discussion was presented sufficiently, except the hypotheses should be revisited.  Thus, after the introduction is edited, the discussion should clearly restate the hypotheses and how the results support or refute those expectations.

Conclusion

---The conclusion is sufficient.  However, it would help the reader understand the application if some of the decision making tools or other aid for sustainable forestry could be explained and cited.  This could a few sentences in the conclusion or at the end of the discussion.  This will help clarify the application of the work, because it is well justified in the introduction – it is not well connected to the discussion/conclusion.

Table/Figure

---The tables & figures were appropriate.

Other revisions

Figure 1, add plot size in parentheses.

Table 2, I suggest using dbh1, dbh2 h1, h2 for clarity with equations.

L262, duplicate periods (.).

L282, larger is misspelled.

Author Response

Manuscript Ref.: forests-750803 “Individual tree diameter and height growth models for 30 tree species in natural forests of Mexico”

 Response to reviewer’s #3 report (first round)

Comments and Suggestions for Authors

The study analyzes growth of individual trees in mixed-species, uneven-aged forests in Mexico. The strength of the paper is developing results for important knowledge gap. The weakness of the paper was unclear hypotheses.  Overall, the paper was well written and covered an important topic in forestry and forest ecology.

Response: Thank you very much for the comments. Following the reviewer’s comments, we have reformulated the paper´s objective for hypothesis clarity (L104-109). We really appreciate very much your valuable comment. For details of the changes, please refer to the new manuscript.

Novelty, Interest, Importance

The justification for the study was explained and cited.  This type of analysis is rare, especially for the forest type. The work is important to share widely.

Response: Thank you very much for your valuable the comments.

Organization

 The paper was well organized and ideas explained.

Response: Thank you very much for the compliment.

Paper summary (Title, Abstract, Keywords)

 I suggest the title to be revised to include mixed-species and uneven-aged – which are too important knowledge gaps addressed with this study.  If this suggestion is used, then the keywords should be revised accordingly.

Response: Thank you very much for the comment. Following the reviewer’s comment, we have reformulated the paper´s title and the keywords were revised accordingly (see L3-4 and L46).

Introduction

The introduction was thorough, except hypotheses were missing.  The authors should state the general hypotheses based on the literature presented in the introduction.  This is important to raising the scientific rigor of the paper.

Response: Thank you very much for the comment. Following the reviewer’s comments, we have reformulated the paper´s objective for hypothesis clarity in the instruction section (L104-109).

Methods

 The methods were detailed sufficiently and seemed appropriate, but this was not an area of analytical expertise for me. The methods could be edited in context to hypotheses.

Response: Thank you very much for the comment. We think that the methods section is written accordingly with the paper´s objectives. We hope the changes done to the paper´s objectives will suffice.

 Results

 The results were presented sufficiently.  I appreciated the interpretative phrases (e.g., LL213-214 “indicating tha(n)t dbh….”.  (“Than” is a typo for “that”.) The results could be edited in context to hypotheses.

Response: Thank you very much for the hint. In the revised version we have corrected this mistake (L216). We hope that the changes done to the paper´s objectives will meet your requirements regarding the results section.

Discussion

 The discussion was presented sufficiently, except the hypotheses should be revisited.  Thus, after the introduction is edited, the discussion should clearly restate the hypotheses and how the results support or refute those expectations.

Response: Thank you very much for the comment. We hope that the changes done to the paper´s objectives will meet your requirements regarding the discussion section.

Conclusion

 The conclusion is sufficient.  However, it would help the reader understand the application if some of the decision making tools or other aid for sustainable forestry could be explained and cited.  This could a few sentences in the conclusion or at the end of the discussion.  This will help clarify the application of the work, because it is well justified in the introduction – it is not well connected to the discussion/conclusion.

Response: Thanks for this interesting comment. In response, we added the following paragraph in the discussion section to explain the application of the models developed in this study (L385-390).

….However, the growth models developed in our study represent useful operational tools to support decision making for a comprehensive variety of tree species in Durango’s forests. They may provide good simulation of growth (diameter, height, volume) for short term projections, provide detailed information about stand structure development (diameter and height distribution), calculate biomass and carbon stocks projection, and allow considerations of a wide variety of silvicultural treatments/prescriptions, among others….

Table/Figure

 The tables & figures were appropriate.

Response: Thank you very much for this nice comment.

Other revisions

 Figure 1, add plot size in parentheses.

Response: Done (L127-128)

Table 2, I suggest using dbh1, dbh2 h1, h2 for clarity with equations.

Response: Thank you for the comment. Done (see Table 2)

L262, duplicate periods (.).

Response: Thank you for the hint. Corrected (L269).

L282, larger is misspelled.

Response: Thank you for the comment. Revised but we do not see any problem (see L288).

Round 2

Reviewer 2 Report

Compared to the earlier version of the manuscript, the authors introduced most of the suggested changes. They modified some parts of discussion, although they did not change the conclusions. I repeat my earlier opinion, that this work is very strongly focused upon the statistical methods of study, with relatively little attention paid to the ecological aspects. However, I acknowledge that this could not be changed easily, considering the limited knowledge about most of the species under study.

Author Response

Response to reviewer’s #2 report (Second round)

Comments and Suggestions for Authors

Compared to the earlier version of the manuscript, the authors introduced most of the suggested changes. They modified some parts of discussion, although they did not change the conclusions. I repeat my earlier opinion, that this work is very strongly focused upon the statistical methods of study, with relatively little attention paid to the ecological aspects. However, I acknowledge that this could not be changed easily, considering the limited knowledge about most of the species under study.

Response: We have found your comment constructive and tried our best to incorporate it in the conclusions of the new revised version of the manuscript. According to the reviewer’s comment, we have added the following sentences to the conclusions section:

L395-397: ….Some of the studied trees species did not show significant competition or site factor effects in the developed models, being the species-specific shade-tolerance and plasticity, respectively, the main reasons for the observed lack of sensitivity to those factors.

L406-407: … Future models should analyze the role of species-specific ecological aspects on individual tree growth, once this knowledge has been generated.

Author Response File: Author Response.docx