The Relative Importance of Succession, Stand Age and Stand Factors on Carbon Allocation of Korean Pine Forests in the Northern Mt. Xiaoxing’anling, China
Round 1
Reviewer 1 Report
Dear Authors,
I was pleased to read your revised paper "The relative importance of succession, stand age and stand factors on carbon allocation of Korean pine forests in the northern M t. X iao ing’anling, China". Thank you to take account all comments of reviewers. You had integrated well the previous comments and suggestions.
I would like you clarify the method that you used to test the normality and the homogeneity of variance and the results de these tests can be added in appendix.
I think your Table 3 is not correct. You presented in the legend the R² (explained variance), but in the contenu you presented, I guess, the coefficient of correlation, because there are negative values in the table whereas the explained variance is never negative. Please re-see this table.
I don't understand this argue: "This is because litterfalls of mainly because the coniferous species (i.e. Korean pine) are 350 compact and dense, and thus difficult to be decomposed by soil animals and microorganisms". Please reworded or re-write this sentence.
Please reworded the title of 4.3
Author Response
Response to Reviewer 1 Comments
Point 1: I was pleased to read your revised paper "The relative importance of succession, stand age and stand factors on carbon allocation of Korean pine forests in the northern M t. Xiao ing’anling, China". Thank you to take account all comments of reviewers. You had integrated well the previous comments and suggestions. I would like you clarify the method that you used to test the normality and the homogeneity of variance and the results de these tests can be added in appendix.
Response 1: Thank you very much for the comments. Based your concern, we have added the Q-Q plots of the multiple regression in appendix.
Point 2: I think your Table 3 is not correct. You presented in the legend the R² (explained variance), but in the contenu you presented, I guess, the coefficient of correlation, because there are negative values in the table whereas the explained variance is never negative. Please re-see this table.
Response 2: Table 3 is the R2 of each variable in explaining carbon storage and allocation pattern, rather than the correlation coefficient, and “-” for negative relationships while others were positive ones. This expression is used in other articles [1].
Point 3: I don't understand this argue: "This is because litterfalls of mainly because the coniferous species (i.e. Korean pine) are 350 compact and dense, and thus difficult to be decomposed by soil animals and microorganisms". Please reworded or re-write this sentence.
Response 3: Thank you very much for your patient review. I’m sorry for this mistake. Changes have been made. We modified as follows: “This is because litterfalls of the coniferous species (i.e. Korean pine) are compact and dense, and this difficult to be decomposed by soil animals and microorganism.”
Point 4: Please reworded the title of 4.3
Response 4: Changes have been made. We modified as follows: “Effects of succession, stand age and stand structure on carbon storage allocation”.
Reference:
- Liang, P.; Wang, X.; Sun, H.; Fan, Y.; Wu, Y.; Lin, X.; Chang, J. Forest type and height are important in shaping the altitudinal change of radial growth response to climate change. Sci Rep 2019, 9, 1336, doi:10.1038/s41598-018-37823-w.
Author Response File: 
Author Response.docx
Reviewer 2 Report
As previously, this paper presents a compelling and very interesting analysis of the principal explanatory factors supporting carbon allocation patterns in the Korean pine forests in Northeastern China. I have now read this paper twice, with great interest. Generally speaking, I find this to be a very compelling account.
I would, however, counsel the authors to consider a few points in undertaking final revisions before publication. The first and perhaps most important is simply to seek assistance for a skilled English language editor. The paper is filled with many smaller grammatical errors and misguided expressions here and there. There are so many, it would be quite time-consuming for me to correct them all… These errors get in the way of a smooth and easy reading of the paper and may discourage some readers. Thus, I would highly recommend seeking some assistance with this. The paper needs to be read through and edited very carefully and meticulously.
Second, the paper is still a bit undecided about its real goal. Are the authors focusing on this topic of carbon allocation in these forests because; a) the topic is interesting, b) they are concerned about achieving the total potential carbon sequestration potential of these forests and contributing to the maximization of the global carbon budget (and Pan’s 2011 numbers), c) are they most concerned about, “coping with climate change [mitigation] and human disturbance”? The paper seems a bit lost in the sense that it is never really very clear what it is the authors are trying to promote or achieve with this analysis? Are they proposing, for example, some kind of related change in forest management strategy? The paper would benefit from greater clarity on this point. The reader might simply ask, if this is a natural succession process, isn’t the natural progression enough in order for the forest to get to this point? Or must it be helped along for some reason?
Third, since it seems that the relationship between succession and total carbon storage in these forests represents something of a novel finding, why is it that previous studies have failed to highlight this result? The arguments supporting this finding seem credible. But it is curious that previous studies have not found this. Can this outcome possibly be better explained?
Fourth, I have also been wondering what this paper suggests for comparisons between natural and plantation forests, for example, in this region? This particular point is never really raised or addressed by the authors. But the results seem to beg the question?
And finally, since I am not personally familiar with this type of forest and the succession process, I have been wondering why it is not possible to simply start by planting pinus koraiensis and nurturing its growth through to the final stage? A couple of sentences about why this type of succession is necessary in this type of forest would be meaningful to the less well informed reader.
Minor editing suggestions: (I am sorry I cannot address all the errors).
- Replace things like: “vegetation below- to aboveground carbon ratio”, with ‘below- to aboveground vegetation carbon ratio’…
- Replace “did not discriminate”(line 67, p4), with: “have not distinguished between”…
- R/S notation: I find this notation is somewhat inadequately explained, since it is never really clearly defined. I assume that belowground carbon does not include soil carbon. But this is only an assumption and I cannot verify it easily from the text. Likewise, in Table 2, since there is ample space in the table, one could write in “aboveground/belowground (R/S)”, instead of the current notation…
- Why is it that aboveground carbon is not the same as the sum of (tree+shrub+herb)?
- P16, lines286-287: I find the general point about soil carbon could be highlighted more strongly and made to stand out more. Since this finding goes against the conventional findings, it could be stated more strongly. And again, why was this not found in previous studies?
Author Response
Response to Reviewer 2 Comments
Point 1: As previously, this paper presents a compelling and very interesting analysis of the principal explanatory factors supporting carbon allocation patterns in the Korean pine forests in Northeastern China. I have now read this paper twice, with great interest. Generally speaking, I find this to be a very compelling account. I would, however, counsel the authors to consider a few points in undertaking final revisions before publication. The first and perhaps most important is simply to seek assistance for a skilled English language editor. The paper is filled with many smaller grammatical errors and misguided expressions here and there. There are so many, it would be quite time-consuming for me to correct them all… These errors get in the way of a smooth and easy reading of the paper and may discourage some readers. Thus, I would highly recommend seeking some assistance with this. The paper needs to be read through and edited very carefully and meticulously.
Response 1: Thank you for the comments on our paper. We’ve carefully revised our grammatical errors and misguided expressions through out the MS.
Point 2: Second, the paper is still a bit undecided about its real goal. Are the authors focusing on this topic of carbon allocation in these forests because; a) the topic is interesting, b) they are concerned about achieving the total potential carbon sequestration potential of these forests and contributing to the maximization of the global carbon budget (and Pan’s 2011 numbers), c) are they most concerned about, “coping with climate change [mitigation] and human disturbance”? The paper seems a bit lost in the sense that it is never really very clear what it is the authors are trying to promote or achieve with this analysis? Are they proposing, for example, some kind of related change in forest management strategy? The paper would benefit from greater clarity on this point. The reader might simply ask, if this is a natural succession process, isn’t the natural progression enough in order for the forest to get to this point? Or must it be helped along for some reason?
Response 2: Thank you for your nice comments on our paper. I am very pleased with your affirmation of our article. Based on your suggestions and concerns, the revised MS has been modified. The successional stages we examined here are successional series due to different disturbance. Our findings useful to better understand the role of species composition on carbon biomass allocation, which are critical to improve forest management (e.g. adjustment of species composition and forest structure). We need to take forest management measures to promote the succession of broad-leaved and Korean pine mixed forests to increasing the carbon storage of forests ecosystems.
Point 3: Third, since it seems that the relationship between succession and total carbon storage in these forests represents something of a novel finding, why is it that previous studies have failed to highlight this result? The arguments supporting this finding seem credible. But it is curious that previous studies have not found this. Can this outcome possibly be better explained?
Response 3: Thank you for your comments. Till now, most studies not explore all the components of forest ecosystem carbon pool, or did not discriminate the different role of stand age and succession when estimate the drivers of carbon storage allocation. However, we found that different components vary with succession, so we suggest that it is necessary to measure the carbon stock of all the components in the future.
Point 4: Fourth, I have also been wondering what this paper suggests for comparisons between natural and plantation forests, for example, in this region? This particular point is never really raised or addressed by the authors. But the results seem to beg the question?
Response 4: Thank you very much for the constructive comments. We studied the difference between natural forests and secondary forests, but the difference between distinguish planted forests needs further study.
Point 5: And finally, since I am not personally familiar with this type of forest and the succession process, I have been wondering why it is not possible to simply start by planting pinus koraiensis and nurturing its growth through to the final stage? A couple of sentences about why this type of succession is necessary in this type of forest would be meaningful to the less well informed reader.
Response 5: The succession of forest communities is a very complex process, which depends on the species renewal characteristics, the external environment, and the phenomenon of substitution of species. Any plant community must undergo a succession process from pioneer stage to climax stage. Since pioneer species (e.g. Betula platyohylla) have relatively low requirements for living conditions, can accumulate more lights and nutrition for the community, and improve the community environment (e.g. soil fertility, canopy density, etc.). With forest succession, the pioneer tree species decreased, which provided suitable environment conditions for the increase of other species (i.e. Korean pine) and evolved into dominant species and constructive species, and finally reached community stability.
Minor editing suggestions: (I am sorry I cannot address all the errors).
Point 6: (1) Replace things like: “vegetation below- to aboveground carbon ratio”, with ‘below- to aboveground vegetation carbon ratio’…
Response 6：Changes have been made.
Point 7: (2) Replace “did not discriminate” (line 67, p4), with: “have not distinguished between”…
Response 7：Changes have been made.
Point 8: (3) R/S notation: I find this notation is somewhat inadequately explained, since it is never really clearly defined. I assume that belowground carbon does not include soil carbon. But this is only an assumption and I cannot verify it easily from the text. Likewise, in Table 2, since there is ample space in the table, one could write in “aboveground/belowground (R/S)”, instead of the current notation…
Response 8: Thank you very much for the comments. Changes have been made.
Point 9: (4) Why is it that aboveground carbon is not the same as the sum of (tree+shrub+herb)?
Response 9: In the MS, aboveground carbon is the sum of aboveground carbon tree, shrub and herb. Moreover, the sum of aboveground carbon storage and underground carbon storage is equal to the sum of carbon storage of tree, shrubs, and herbs.
Point 10: (5) P16, lines286-287: I find the general point about soil carbon could be highlighted more strongly and made to stand out more. Since this finding goes against the conventional findings, it could be stated more strongly. And again, why was this not found in previous studies?
Response 10: Thank you very much for the comment. We have given a detailed and reasonable explanation in the Discussion, see 4.1.
Author Response File: Author Response.docx
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript deals with ecosystem C pool and allocation and its influencing factors in four successional stages of forests in the northern China. They have enough data set of ecosystem Carbon storage（including Biomass, dead trees, soil carbon). Successional effects including species change for C storage especially for natural temperate forests are important for global carbon cycle and future prediction.
They have three explanatory variables, i.e., succession, stand age, stand factors, to the objective variable as carbon storage and allocation, and the author try to reveal “the relative importance of succession, stand age and stand structure on carbon storage and allocation”.
However, I have questioned to experimental design and site selecting to analyze ”the variation of the carbon storage and allocation with succession, stand age and stand factors” (L76). Main two major flaws are as follows;
(1)
Most important flaw is the setting 4 stages of forests. There are no description of community structures (e.g., full species composition and there relative dominance, dhb and hight class distributions of each species, and so on), and historical backgrounds of theses 4 forests. Thus, actually I wonder these forests are really successional stage of these areas.
For example, Quercus mongolica forest of middle stage has clearly changed from Betula forest?, and when does it change occurred? If former forest of Quercus is Betula dominated forest, there are some trace of previous stage, e.g., remnant canopy trees of Betula in Quercus forest. Or, Betula forest of early stage include seedling or sapling of Quercus trees? and so on.
Moreover, how do you distinguish mid-late and late successional stages in Table 1. Dominant species are the same in mid-late and late stage, and stand age is also nearly the same from Fig.2 (ca 80yr vs 85 yr?). Stand volume greatly increased (Table 1) and soil organic carbon decreased (table 2) from mid-late to late stages only less than 10 years progress.
In these cases, I have doubt for the site selecting for chronosequence without the comparisons of community structures and history among sites. I think that these forests are not chronosequence but different forest types caused by some historical backgrounds such as effect of human disturbances.
(2)
They have three explanatory variables, i.e., succession, stand age, stand factors, but I do not understand the “succession” for explanatory variable. The author calculate the contributions of each factors in Table 3, and Fig 4, but what is “successional factors”, numerical number? no explanation of succession in Methods section??
I think the succession is the function of stand age, community structures are also change with succession. So I think, variations of succession, stand age, and stand factors are self-correlate, anyway I wonder what is factor of “succession”
Moreover, stand age and tree age is completely different for natural temperate forests that include successional change of species composition. From fig 2, each “tree age” for each successional is ca., 55, 65, 78, 85 yrs. However, if late stage of mixed forest succeeded from Betula -> Quercus-> Pinus, stand age should be more than 200 yrs!
In this manuscript “stand age” means just “tree age after successional change”, but not stand age of each forest. In this case, I don’t know what is the age effects for C storage and allocations.
As a result, I can not judge the answer of two scientific questions, because there are serious flaws of experimental design.
Reviewer 2 Report
This paper provides a compelling and data rich analysis of variation in carbon storage across different successional stages and changes in stand structure in a mixed forest in Northeast China. Generally speaking, the authors provide a very detailed picture of changes in stand structure across 4 successional stages in a forest composed of Korean pine and broad-leaved species. Though the data is generally well-described and the authors clearly highlight successional and stand structure-related change in this forest, the authors generally do not seem to take their analysis to the next level. The authors point out at the end of the abstract that, ‘the information about carbon allocation patterns and their influencing factors is important for decision-making in sustainable forest management and climate change mitigation’. However, the authors never really succeed in explaining how or why this might be the case. Thus, I would encourage the authors to try and make this theoretical leap in a moderate revision of the current text. This discussion should appear throughout the text (abstract, intro, discussion and conclusions).
Generally speaking, it would be helpful to both highlight any particular controversies that dominate discussion on this topic, and to explain why the findings in this particular study are important…?
Minor Issues:
The text requires significant language editing and should be carefully revised. I would suggest a more careful highlighting of the explanatory variables used to describe stand structure and succession. This would, in particular, be helpful in better understanding how the analysis that appears in Section 3.3 and Figure 4 is derived. Thus, if these categories are used to organize the data in the above sections, figures and tables, this might be helpful for improving our understanding of this last step in the analysis. Though I have not been exhaustive, I have attempted to provide suggestions for improving the language quality throughout. It would however be best if the text could be edited by a native speaker. Though the past tense is frequently used in the text to describe the data and methods, I would generally recommend the present tense. Please see the attached text for additional editing suggestions.Comments for author File: 
Comments.pdf
Reviewer 3 Report
Dear Authors,
I was pleased to read your paper "The relative importance of succession, stand age and stand structure on carbon allocation of Korean pine forests in the northern M t. X iao ing’anling, China". I have some comments on the writing and the scientific content of your manuscript.
On the writing, I thing that this paper reads very well, but there are still some parts where the writing is not of good quality (Abstract, Introduction and Discussion). I suggest you to re-read this paper with more time or to give it at another person which is not a co-author.
On the scientific content, I think that all elements of the scientific content are present and the results are original and significant. I would just like to suggest that you clarify some parts of the methodology and the results so that everything is much clearer. First, your carbon estimates and other structural parameters were reported at what scale? plot? or subplot? How did you estimate the Dmax and Hmax? Please mentionned the results of stepwise regressions. Please give us the figure or table of results of the normality test and the homogeneity test of variance in the supplementary material. I don't think Table 3 of the contributions of each variable is not appropriate, otherwise you can put it in the supplementary material.
