Allometric Growth of Common Urban Tree Species in Qingdao City of Eastern China
Round 1
Reviewer 1 Report
The strength of the manuscript is data accumulation of stem diameter, tree height and crown size from 15 urban tree species and allometric analysis of these parameters. The manuscript is weak in answering scientific questions. What scientific question(s) did the authors aim to answer? What implications did the results have?
For example, the growth of urban trees is altered by management practices, thus the allometric relationships might have different forms with those of rural trees. A scientific question is how much does management practices influence allometric relationships in urban trees? Another example, what did the difference of the allometric relationships in the 15 tree species imply for biology of tree species? As for the application of the study, the authors mentioned that their study “provide theoretical basis for planning, construction and management of urban forests” (lines 110-111), yet I did not find practical recommendations for management of urban forests.
I have no questions on the actual calculation and the results of the allometric relationships among the studied tree characteristics.
Author Response
>Response: We appreciate the positive comments on the manuscript, but are also happy with the reviewer critical comments since they helped us to improve the manuscript with clear focus. We have rewritten the last paragraph of the Introduction section and added research question in the revised manuscript. The influence of management measures on the allometric growth relationship of urban tree species and the specific and feasible urban management suggestions, our research data are only for the urban street trees in Qingdao, and the focus is to provide data support and model reference for urban forestry planning, construction and management. The allometric growth relationship of the same tree species under different management measures and the specific urban planning management suggestions are not within our specific research scope. As well, we have included implications of the results in the Discussion section.
Reviewer 2 Report
The work of this MS can play an important role in the estimation of carbon storage in cities. But the shortcomings are obvious.
Firstly, the difference of urban trees between cities is greatly affected by the environment, such as the soil where the saplings were transplanted has a significant effect on their growth. In the process of growth, greening trees are greatly disturbed by management. The results have no general applicability. Secondly, the pure theoretical model needs to be corrected by measured data, but there is no logging measured data for biomass. And it is more in line with the actual situation that the CV should be a conical calculation volume. Finally, many language expressions need to be re-combed.
Author Response
>Response: Many thanks for the reviewer’s suggestions. We agree on the uncertain factors on urban tree growth and did not include the management impact since we do not have the data. Secondly, we explore the general allometric relations of urban trees to discover if there are differences among the tree species and what does the differences imply for the tree biology, rather quantify the urban tree biomass. Our study included coniferous and broadleaved species. The tree crown volume calculation in our study was based on a study by Pretzsch et al. in 2015, which did not analyse different canopy structure. The correlation between canopy structure and tree model will be the point of our future research and here we explain it in the Discussion section (Page 16-17). Lastly, we have rephrased a large number of language expression in the revised manuscript.
Reviewer 3 Report
The first sentence of the abstract is incomplete. Please complete the sentence.
I suggest authors to analyze and give results in each figure the least squares regression along with quintile regression
Page 3, 134-135: Bring the sentence in the result selection
Page 5, 181: Which package of R was used for analysis?
Page 5, 182: Give a brief of quintile regression and the reason for doing quintile regression in the present study.
The result of 5 and 50% quintiles have not been discussed. What is the reaseon?
Authors have only done fitting of allometric equation. No validation of model has been done.
I suggest authors divide the data for each species into two parts. (75 and 25). Use the first 75 % of data for model fitting for each component. and then validate the model using remaining 25% data
Author Response
The first sentence of the abstract is incomplete. Please complete the sentence.
>Response: We have completed the sentence by adding some descriptions in the revised manuscript.
I suggest authors to analyze and give results in each figure the least squares regression along with quintile regression.
>Response: Many thanks for the reviewer’s recommendations. Since our data are relatively dispersed, we are interested in quantifying the upper and lower boundary with different crown shapes rather than quantifying the conditional central tendency of the tree allometry by ordinary least squares (OLS) regression. Therefore, we only include the quantile regression results but did not show least squares regressions.
Page 3, 134-135: Bring the sentence in the result selection
>Response: Thanks for the reviewer’s suggestions. We have moved the sentence to the Results section.
Page 5, 181: Which package of R was used for analysis?
>Response: Many thanks for the reviewer’s reminding. We have written the package of R (R version 4.2.2 (https://cran.r-project.org/) in more details in the revised manuscript.
Page 5, 182: Give a brief of quintile regression and the reason for doing quintile regression in the present study.
>Response: We agree and added some arguments of applying quantile regressions on Page 6.
The result of 5 and 50% quintiles have not been discussed. What is the reaseon?
>Response: Thanks for pointing this out for us. In the method section, we mention the use of quantile regression to fit 95% quantiles to represent trees under open growth, and 50% and 5% quantiles represent average and suppressed trees. This study aimed at urban street trees in Qingdao, which grow under relatively open conditions, so the manuscript results and discussion section focuses on 95 % quantile regression. Here we add the narrative in the result section on Page 6 in the revised manuscript.
Authors have only done fitting of allometric equation. No validation of model has been done. I suggest authors divide the data for each species into two parts. (75 and 25). Use the first 75 % of data for model fitting for each component. and then validate the model using remaining 25% data
>Response: Thanks for the reviewer pointing out. We have added the model validations in the appendix in the revised manuscript. As replied earlier, we are interested in determining the upper and lower boundary with different crown shapes, and that is why we did 95% and 5% quantiles rather than 75% and 25% quantiles which fall between 95% and 5% quantiles.
Round 2
Reviewer 2 Report
The authors have made a lot of improvements in the manuscript, and now it is much better than before. But there are still some problems.
There have been many papers on the allometric growth equation of tree species growth. Due to the differences in the biological characteristics of tree species and the environment such as light, water and soil, the growth of trees will be affected. To test the regression relationship between DBH and CV, CW and CPA of different tree species are the main work of this MS, which does not involve in the in-depth detection of tree biological characteristics, such as photosynthetic rate, but only in the discussion section with a Shallow part: coniferous/ broadleaved or shade/light tree species. So “what does the difference imply for biology of urban tree species?” cannot be a main part or results of the MS. If the authors want to discuss the biological characteristics, it is recommended to increase the deep phenological period, physiological and ecological indicators, etc.
The Latin of all tree species in the figure could be italic.
“To our knowledge, this study is the first to quantify the urban tree allometry” A method used in a new place or species is not an innovation.
Author Response
The authors have made a lot of improvements in the manuscript, and now it is much better than before. But there are still some problems.
There have been many papers on the allometric growth equation of tree species growth. Due to the differences in the biological characteristics of tree species and the environment such as light, water and soil, the growth of trees will be affected. To test the regression relationship between DBH and CV, CW and CPA of different tree species are the main work of this MS, which does not involve in the in-depth detection of tree biological characteristics, such as photosynthetic rate, but only in the discussion section with a Shallow part: coniferous/ broadleaved or shadeght tree species. So “what does the difference imply for biology of urban tree species?” cannot be a main part or results of the MS. If the authors want to discuss the biological characteristics, it is recommended to increase the deep phenological period, physiological and ecological indicators, etc.
> Response: Thank you very much for the reviewer 's opinion. We agree with this view and believe that this aspect is too shallow to a large extent. Here we add some content to the Discussion section in the revised manuscript.
The Latin of all tree species in the figure could be italic.
> Response: Thanks to the reviewer's suggestion. We have modified the figures.
“To our knowledge, this study is the first to quantify the urban tree allometry” A method used in a new place or species is not an innovation.
> Response: We thank and agree with the reviewers. The expression of this part of the content we re-adjusted in the revised manuscript.
Reviewer 3 Report
All the comments have been incorporated in the revised article. May be accepted in present form
