Vertical Variation in Leaf Traits and Crown Structure Promote the Coexistence of Forest Tree Species

Round 1

Reviewer 1 Report

Dear colleagues!

The authors' research is quite interesting, fundamental and promising. To understand the vertical structure of phytocenosis, it is necessary to have an idea of the ecological niches of plant species populations. The authors considered the differentiation of individuals of plant species depending on the limiting factor in this community – light.

There is  competent and persuasive introduction In chapter 2, the authors described in detail the research methods and gave calculation formulas. The using of modern statistical methods inspires confidence in the results of the research.

The authors also described in detail the results of the work, illustrated their judgments, and conducted a competent discussion of the results.

However, for a slight improvement of the manuscript, I recommend making some additions.

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Author Response

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Reviewer 2 Report

Reviewer comments to Forests 1819095, "Vertical variation in leaf traits and crown structure promote the coexistence of forest tree species" by Feng et al.

This document reports the variation in carbon assimilation and leaf structural traits within seven species from a subtropical forest in China. The main results are that species can be classified by their functional characteristics according to their height category within the canopy.

Overall, the paper is well written, and the subject is interesting and appealing to ecologists interested in plant functional ecology. However, to allow a solid contribution to forest ecology, this document should be corrected in several aspects, both in the analysis and result presentation and in the format to display results:

1. The analysis considers Tukey posthoc tests to separate groups and species. There is a methodological aspect that is not considered, which is the lack of independence in the dataset. Species are from three families, and that implies that phylogenetically corrected analysis should be employed. 
2. The ANOVA values are not presented. Before introducing the Tukey tests, it is critical to know what traits vary across species and categories. 
3. There is no indication of intra-specific variability across tree height. Several articles have found that within the same trees, leaves obtained from the lower part of the trunk have shade leaves, and the upper part has sun leaves. There is no indication of this type of variation within the dataset presented. It would be relevant to have graphics of the overall variability within individuals, species, and canopy layers to evaluate if trees are disgregated according to their height habits.
4. Figures. The graphics are scarce to provide relevant information. There is not even an indication of the type of central tendency metric employed (mean? median?)—the same for dispersion metrics. Instead, I would recommend using boxplots. The horizontal orientation of the graphs is not recommendable either because there are only three cases in the categorical variables. The Y-axis should include the quantitative traits and the X -axis the categorical traits.  

4.1. There is no indication of the statistically different treatments. There are no across-species analyses of variance for all traits, only for the pairs (this analysis should be phylogenetically corrected). First, authors should show if all species differ in the traits (expectable), then if the canopy layer influences the variation in functional traits. 

 

Overall, the information is relevant, but there are several analytical factors that currently limit the explanatory potential of this document. I sincerely expect authors to solve these limitations and produce a solid and relevant document.

 

Minor comments.

 

Abstract.

First sentence, L 11-13. This sentence is unclear and misleading, as multiple causes for the high diversity of the tropical biota are sustained by the evidence, from pathogen selection, patch occupation, environmental stability and low extinction rates, high divergence rates, etc. I would suggest directly tackle niche occupations in the elevation and hydraulic gradient within trees, such as:

"Stratification in trees may respond to selective pressures to enhance light interception; therefore, the vertical functional variation in leaf traits may indicate niche partitioning within forests." In this study...

L. 131, 150 Italics in species names.

Tables: a first table is needed, with the species list, families, abbreviation (using only four letters, such that Machilus chinensis = Mach, etc.), and position within the canopy. 

Table 2. Traits. Include a list of all traits measured in this study, the abbreviation, units, and if possible, a column indicating interspecific variability (using * for P values between 0.01 to 0.05, ** 0.001 to 0.01, and *** lower than 0.001).

Author Response

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Round 2

Reviewer 2 Report

Reviewer comments to Forests 1819095, titled "Vertical variation in leaf traits and crown structure promote the coexistence of forest tree species," by Jiayi Feng et al.

 

I have reviewed a much-improved version of this article. The authors have successfully answered all my queries. Therefore, I have only two minimal suggestions:

 

1. Reducing the number of graphic elements in figure 2. This figure includes ANOVA results for functional, photosynthetic, and canopy traits. I suggest partitioning this figure into three, one per category. 
2. Reducing the number of tables. Table 3 is the comparison in species pairs, which can be better placed as an appendix, with table 4 (accompanying figure 2) and table 7 (accompanying figure 3).
3. 3. I did not find the figure for intraspecific variability among crown parts; I probably get lost, but I would suggest sending this table (6) to appendices and enhancing the figure comparing intraspecific variability for all species only.

Thank you for this interesting article,

 

Sincerely

Author Response

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