Characterizing Diameter Distributions for Uneven-Aged Pine-Oak Mixed Forests in the Qinling Mountains of China

Round 1

Reviewer 1 Report

General comment

The work concerns the standard problem of modeling tree diameter distribution. The novelty of the work is the development of a model for uneven-aged mixed forest and the use of two approaches to estimate the Weibull distribution parameters combined with three recently proposed (Cao, 2004) methods of estimating the parameters of regression equations. Comparison of the effectiveness of the methods used will be interesting for many readers.
Since the applied estimation methods are not standard components of statistical software and require the development of appropriate calculation algorithms, it is advisable to accurately describe how the authors implemented these methods: in which software the calculations were performed, whether its own algorithm or existing one was used, if its own should provide it in the annex, if the existing one should give a reference to the literature. I think that the supplementation of this information will be expected by readers.

Specific comment

lines 73-75: The authors give the number of plots dominated by individual species and specify the names of groups in parentheses. Does the results presented in the tables refer to the "groups of plots or species" described here? Is the term "species group" used later, is the same as described here or means something else? Please explain this, especially since the authors use the term "group" in relation to the cross-validation method.

Author Response

General comment:

Since the applied estimation methods are not standard components of statistical software and require the development of appropriate calculation algorithms, it is advisable to accurately describe how the authors implemented these methods: in which software the calculations were performed, whether its own algorithm or existing one was used, if its own should provide it in the annex, if the existing one should give a reference to the literature. I think that the supplementation of this information will be expected by readers.

The details about how to implement the methods, as well as cited references, have been described as suggested (Lines 132-134, 375 of revised ms).

Specific comment:

lines 73-75:

The authors give the number of plots dominated by individual species and specify the names of groups in parentheses. Does the results presented in the tables refer to the "groups of plots or species" described here? Is the term "species group" used later, is the same as described here or means something else? Please explain this, especially since the authors use the term "group" in relation to the cross-validation method.

The previous statements were not clear enough. Definition of “species group” has been clarified as suggested, and it is the same with the results presented in tables (Lines 79-83 of revised ms).

Reviewer 2 Report

I have some comments detailed below with reference to corresponding line numbers.

(58): one of the proposed objectives is to “develop diameter distribution models for uneven-aged pine-oak mixed forests in Qinling Mountains of China”, but the location is not mentioned in this way in the title. One of the crucial issues of the statistical analysis is to ensure representativeness at the considered level. Either the title will be changed, or it will be specified in the text that the uneven-aged pine-oak mixed forests are found only in the Qinling Mountains.

(65-66): “Plots of size 0.04 ha (20 m × 20 m) were randomly established”. Also related to representativeness, some clarifications should be made: how the plots were distributed on the surface (a map figure would be appropriate), as well as how many plots were set up in each stand? If in every stand was considered one single plot, is this enough to capture the true structures present in those stands? A bibliographic recommendation for possible clarifications: Janowiak, M.K., Nagel, L.M. and Webster, C.R. “Spatial Scale and Stand Structure in Northern Hardwood Forests: Implications for Quantifying Diameter Distributions” FOR. SCI. 54(5):497–506.

(71): “total amount of trees of all the miscellaneous species formed a considerable proportion in the stands”. You should specify more precisely which was the minimum proportion for which the stands dominated by all the miscellaneous species were pooled into one species group in this study?

(78): I recommend using the same y-axis representation scale for all the graphs in Figure 1, and with 4-cm for diameter class. Furthermore, it seems to be an inconsistency in class formation along analysis: classes of 1 cm here, of 2 cm at line (141) and of 4 cm at line (236). I think it would be kept the size of the class for which the Weibull distribution parameters were determined, otherwise at least the parameters b and c would have other values.

(98): “Because most pine-oak forests are uneven-aged”. “Most” or “all” of them? Not just uneven-aged stands were analyzed?

(195-196): “The backward elimination approach applied in this study has the advantage of keeping “good” sets of variables intact”. It requires additional explanations. Otherwise, someone might suspect that a subjective choice has been made.

(246-247): Those thinning operations were performed simultaneously in all 22 plots dominated by P. tabulaeformis? And preferential from the diameter class of 15 cm? It would require further clarification.

(252): I recommend using the same y-axis representation scale for all the graphs in Figure 3. In order to have a graphical representation of the goodness of fit for proposed Weibull model, the overlapping representation of the experimental distribution would be expressive, at least for all species, if not for each separately.

Author Response

Please see the attachment.

Author Response File: Author Response.docx