Spatial Patterns and Interspecific Associations During Natural Regeneration in Three Types of Secondary Forest in the Central Part of the Greater Khingan Mountains, Heilongjiang Province, China
Round 1
Reviewer 1 Report
This is an original and important contribution to the knowledge of the spatial structure of natural secondary forest. The authors use modern statistical methods, illustrating various aspects of the spatial distribution of tree species in secondary forest. They analyzed intraspecific and interspecific relations of trees in various growth stages. The detailed analysis is very impressive. Despite the potential high scientific value of this manuscript, it needs substantial improvement, according to the recommendations provided below.
Why these three particular forests were chosen for the study, out of all secondary forests of the Greater Khingan Mountains? Is there any rationale for this choice ? Or underling (but not pronounced) hypothesis? Since the comparison of the plots is an important part of the study, a detailed description of all three forests is essential. What is the age of the forest (or the oldest trees), what are the light conditions, herbivore activity, current use of these forests are any differences in soil quality, water availability or any site conditions etc. Data about the history of these forests is also needed. When the clear-cut was made? Were any trees left (for instance, young trees without economic value, regeneration or old trees of bad quality)? 2 Plot design and survey section needs to be completed with additional details.
Line 131. - “state” what it is exactly (alive or dead)?
How the DBH was measured: with caliper? One measurement in a random direction? Average of two perpendicular measurements? What equipment the height of trees was measured with? How the crown width was measured? Why the crown width was not analyzed in the manuscript? What methods were used to record the position of the trees?
Line 132. “basal diameter (DBH<5cm)” - DBH mean Diameter at Breast Height so diameter 5 cm above soil level (or lower) is not DBH
All captions under figures contain a detailed explanation of the abbreviations, colors, types of lines, etc., but do not contain the figure title. For example
Figure 1. Distribution of trees in DBH classes on study plots in the Greater Khingan Mountains. (or something similar)
Line 176. “CMF” should be CBMF? Lines175-178. The stems in class 10-15cm in BF and CBMF were not thicker but slightly more numerous. Bur the real question is, whether the slight difference in numbers of trees in class 10-15 cm between BF CBMF plots and CMF is important? Using other class widths (wider or narrower) the diagram may look differently. There is no strong evidence that the DBH distribution on three plots differ significantly. Moreover, such distribution is typical for old multicohort forests with dense first stand story and thick understory composed of shade-tolerant species, the later die heavily because of no possibility to be recruited to the first story (for example see Goff and West 1975). The Result section describes all possible interactions of spatial structure on studied plots. As a result, crucial analyses (like spatial distribution of old trees and their offspring) are mixed with analyses of minor importance (like spatial distribution of seedlings and sapling of the same species). The authors seem to be tired of the long result section and in the end part (since line 420) they do not cite figures. Figures 8, 9, 10 are not cited in the Result section. Lines 450-453. It is better to analyze the spatial distribution of sylvestris trees in relation to distance to dominant L. gmelinii trees (like before), do not introduce proportions of positive to no association which in fact give no information about the real pattern of spatial distribution Lines455-457. Should be: davidiana and S. triandra presented negative associations with L. gmelinii at 1-25 m scales and 1-20 m scales, respectively, and all showed no associations at other scales. Lines 484, 485. An alternative explanation of the random distribution of adult trees of gmelinii is also possible: adult trees appeared on a clear-cut area on early stages of stand development. They were brought by strong wind from adjacent stands (seeds are winged), so they were not concentrated around mother trees but were randomly distributed from the very beginning. In fact, we do know nothing about the origin of adult L. gmelini trees. Lines 494-496. This sentence explains the aggregated distribution of platyphylla as a result of seeding from adjacent stands, while the same process was described as a reason for random distribution, described a few lines above (lines 489-491). We simply do not know the history of these stands, maybe some gaps were present in BF stands filed later by B. platyphylla seedlings or patches of slightly different soil properties. If the author’s explanation is correct, a better rationale is needed. Lines 497,498. Habitat heterogeneity is the characteristic of the habitat itself, not adjacent habitats. It means heterogeneity in soil fertility, ground flora cover, water conditions, light conditions, etc. Lines 501-503. Yes, but figures 6 and 7 do not support such a statement, and show that old platyphylla does not promote young ones. Lines 515-517. Yes, gmelini suppresses P. koraiensis on small scale. Lines 517-519. No, L. gmelini does not promote P. koraiensis on large scale. Positive association was observed at the 20-50 m scale. It is far behind the crown projection of L. gmelini where the suppression effect is weak or not present at all. Lines 540-555. This section is difficult to follow. What is the difference between dominant and main species? Line 551. What population mean in this sentence (population is a set of individuals of one species in biocenosis). In my opinion, it is necessary to explain the theory of spatial patterns of trees in successional stages in the Introduction section. It helps to understand this part. Lines 561-563. See recommendation 6. Line 568 habitat heterogeneity was not studied. See recommendation 12. Line 571. Should it be CMF instead of CMBF? But the occurrence of Mongolian oak (heavy seed species) on CMF suggests the most advanced succession on this plot, and over 90% dominance of Betula platyphylla (species with the lightest seeds) on BF suggests the youngest stage. Of course, it is just remarked for the author’s consideration to help them to make their interpretation stronger. Line 574. In my opinion, this manuscript gives data to more specific recommendations for the practice, for instance: the use of B. platyphylla as promoting species for gmelini, the use of L. gmelini as promoting species for P. sylvestris, intensive thining in L. gmelini stands to promote P. koraiensis . These issues should be described in detail in the Discussion section.
Author Response
Dear Reviewer,
I have completed the revision of the manuscript, and I have responded carefully and carefully to each comment put forward by the reviewer. For the comments given by the reviewer, I responded with red font in the manuscript, and other fonts are my responses to suggestions from other reviewers. We hope that our responses will satisfy you, wish you a happy life, and hope that our manuscript will be published smoothly.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
The manuscript you submitted seems to be interesting. However, I found some critical flaws which must be clearly improwed.
All comments are listed in the attached document.
Comments for author File: 
Comments.pdf
Author Response
I have completed the revision of the manuscript, and I have responded carefully and carefully to each comment put forward by the reviewer. For the comments given by the reviewer, I responded with yellow highlights in the manuscript, and other fonts are my responses to suggestions from other reviewers. We hope that our responses will satisfy you, wish you a happy life, and hope that our manuscript will be published smoothly.
Author Response File: Author Response.docx
Reviewer 3 Report
The regeneration of secondary forests is important not only for China but also for increasing global forest cover to reduce CO2 emissions.
Introduction
The introduction describes what are secondary natural forests, its importance, and the problems of forest regeneration. Here I miss the review of other authors' research on this topic, especially the 2015-2019 articles.
Metods
119 What is the soil according to World Reference Base for Soil Resources?
In 131 Write DBH explanation.
Results
In the first figure, the notes should be larger. Visual differences between different forest plots would be better visible if the y-axis scale would be the same (3500).
The discussions are described in detail and the results are consistent with the conclusions
Author Response
Dear Reviewer,
I have completed the revision of the manuscript, and I have responded carefully and carefully to each comment put forward by the reviewer. For the comments given by the reviewer, I responded with green highlights in the manuscript, and other fonts are my responses to suggestions from other reviewers. We hope that our responses will satisfy you, wish you a happy life, and hope that our manuscript will be published smoothly.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The revised version has been significantly improved.
I suggest one more correction in lines 124-125:
(alive, dead and downwood, etc.), DBH, tree height, crown width (for trees with DBH≥5 cm), ground diameter (GD<5 cm above ground level) and coordinate position were recorded. DBH and GD was measured with tape meter, the height
Author Response
Dear reviewer,
I have completed the revision of the manuscript. We hope that our responses will satisfy you.
Author Response File: Author Response.docx
Reviewer 2 Report
Dear Authors,
The manuscript at the present form seems to be worth to publish. I am satisfied the correction you did.
Reviewer 3 Report
Thanks to the authors for their efforts. All comments were noted. Only maybe you could make bigger the fonts of notes in the first figure?
Author Response
Dear reviewer,
I have completed the revision of the manuscript. We hope that our responses will satisfy you.
Author Response File: Author Response.docx
