Multi-Criteria Plant Clustering for Carbon-Centric Urban Forestry: Enhancing Sequestration Potential Through Adaptive Species Selection in the Zhengzhou Metropolitan Area, China

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is interesting and dealing with a contemporary topic of urban green space management. In this study, authors have tried to explore multispecies availability with respect to multi-dimension landscape features. The study seems to be partially novel as there are a number of studies which dealt with urban green spaces, plant species characterization and exploration of carbon sequestration potential of different plant species. Still this manuscript have some novelty by using models for estimating carbon sequestration potential, potential areas for future carbon sequestration estimation and multispecies concept. Site-specific species-based sequestration was also highlighted in this study. Overall, the manuscript has merit to be considered for publication. However, there are a few concerns which need to be addressed thoroughly before proceeding further. The Abstract can be improved for more clarity. Methodology section needs some details at a few places. A separate Statistical analysis section can be included in the Methodology by highlighting different statistical analyses conducted such as ANOVA and Post-hoc, correlation, if any. The results section can be concise for more clarity. The key findings need to be clearly highlighted in discussion section as the flow is missing in discussion section. The captions of figures and tables are abruptly presented which need to be more clear and precise. Also, if the figures and tables are formed using AI, it can be improved for more clarity. If the help of AI is taken while developing the manuscript, some sentences can be better presented. There are a number of typological errors in the manuscript which need authors' attention. 

An additional pdf file with annotated corrections and suggestions has been included with this letter. Authors are advised to go through the same for specific comments.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Review of Ren et al.
Thank you for the opportunity to review this fascinating article demonstrating practical cluster4ing of landscape trees with respect to their differential contributions to urban landscapes, having an eye on carbon storage, aesthetics, and practicality.  The urban forestry value of the contribution is obvious and compelling.
Although I detected no major  issues, and feel that the paper merits ultimate publication, there are numerous stylistic/conventionality/clarity/organizational considerations to address.
Plant names through the ms. are not in any conventional style.  Although this would be corrected during copy editing, prior to that,  it may help the authors during revision (or with subsequent review) to suggest:
•    Not mixing English names and botanical names.   Give the botanical names for everything (then with English names added optionally).   Cultivar names can be iffy in imprecise, and arguably may not be worth including.  Although no harm in it.
•    Italicize genus names and specific epithets, but not author names, and not cultivar names in single quotes, and not the word “var.”
•    It is not conventional to repeat the author name with each appearance of a species.  What is more usual is to include the authorship on the first appearance in the ms….or if all species names are in a table, the authors might go ok there.
•    I’d suggest omitting authorships from the abstract.
•    Do not put author names in parens() unless there is another name following the parens.   Genus species (author) is wrong for plants.  Genus species (author) another author is correct.
•    Not necessary, but it would be nice to give the family for each species, in the species table.
•    Hybrids have authorship (Photinia Xfraseri Dress, line 237).
It would help to indicate if species are native to the region or not, maybe in species table.
Tables S1 and S2 are very useful to the reader.  If editors and space permit, is there a chance of including them in the article, maybe as an appendix?   Those tables could be then expanded to include authorships, families, native or not.
There is a mildly confusing mix of carbon-sequestration terminology, especially but not entirely early in the paper before Sect 2.3.   Not in the abstract,  I suggest defining  the abbreviations with units in one place early before further use: 
CS (kgC)
CS density (kgC/mm2)
CSE (kgC/year) 
CSE capacity (kgC per year per m2).    

What is the difference between CSE capacity (as defined on line 138,  and CSE density (kgC per year per mm2 ) as used on lines 261 and 262?     Are CSE density and CSE capacity being used interchangeably?  If not, a sharper distinction may be needed.    If so, it would help to settle on one term.   Iin places in the ms. where “sequestratrion” is used (e.g. Fig 5, Fig. 7 captions, line 322, 411, 413), it would help to use the full appropriate abbreviation.
Fig. 2. Typo in “Building,”    Then again (“Buding”) on line 168.
Fig. 4f, typo in top line
Fig. 4 caption.  Please give more info, such as a-e being trees, f-j being shrubs. 
Fig. 4 e and j, change “Carbon Sequestration” to CSE or the Carbon Sequestration Efficiency? 
Fig. 4 a and f, make x-axis labels the same
Fig. 5 Compare “PingDingShan” with same name on line 254.
Fig. 5 caption.   Key to abbreviations?   What do the error bars represent?
Fig. 6. Some of the colors are hard to distinguish (group 9 vs. 3, 8 vs. 7), at least in a laser-printed review copy.
Fig. 7. Color legends: change CES to CSE?   State in caption what are a, b, and c. Define pre- and post-.   Say that top label refers to lines and bottom label to bars.
Fig. 7.  I am probably misreading or overlooking something(!), but  I can’t match the numbers in lines 295-303 to Figure 7.  
Line 163. Give citations.
Lines 171, citation?
Line 246   “CSE efficiency”?    Should be CSE capacity?
Line 258, Does “sequestration” mean CSE here?
Line 298. Use same units as Fig. 7.
Section 3.2.   Maybe space is not available, but if it is possible, can you list the full membership in each group within the article itself?   Appendix?
Line 272, does Cluster 9 tend toward high ornamental value in Fig. 6.
Table 1.  At least for the U.S, give the states for the cities.  Some city names apply in multiple states (e.g., Lincoln, Moorsetown).   Or merely five the states as is done with some entries (e.g. Florida).  Does New York refer to the city, or the state?     https://geotargit.com/citiespercountry.php?qcountry_code=US&qcity=Lincoln#google_vignette
Line 368-394 vs. line vs. line 267-288, discuss the cluster results in just one place.   Maybe tabulate clusters in Results section or Appendix  and discuss in Discussion section?
Part of the Discussion woobles far from the results of the present article., and in places prior work sounds confusingly  like present results (line 426). Lines 433-443 seem to belong in the Intro, not the Discussion. 
Line 415 Pg ok? Picograms?
To repeat, it seems hat the article has “good bones” and will soon make a fine and useful publication, but only after addressing  several little issues mostly having to do with species names conventions, clarity, consistency, and organization.   

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript "Multi-Criteria Plant Clustering for Carbon-Centric Urban Forestry: Enhancing Sequestration Potential through Adaptive Species Selection in the Zhengzhou Metropolitan Area,China" by Ren Qiutan et al. aims to assess  plant carbon sequestration (CSE) capacity at the regional scale of the Zhengzhou Metropolitan Area (ZMA).

Despite its high practical significance and extensive fieldwork, this manuscript cannot be accepted in its current form due to the critical limitations of the description of the data collection and extrapolation methods used.

In addition, the research question itself raises questions. Main aim is stated as to assess plant carbon sequestration (CSE) capacity at the regional scale of the Zhengzhou Metropolitan Area (ZMA), but the spatial extrapolation of the results is not explained at all. The next aim is hierarchical and cluster analyses of plant species with balanced CSE capacity. It is solved and quite logically based on the results of species diversity of surveyed UGS of the study area. However, the next aim on vegetation regeneration modelling looks disconnected from the previous ones, since the selected regeneration scenarios have little connection with the types of objects surveyed in the first objective, the text does not explain why the initial condition of sites and even their size were chosen in different scenarios.

Therefore, the main recommendations for the work is to enhacne methods description and a serious revision of the text, from which it will be clear how the third aim is related to the first one and on what data it is based on.  

The level of English is acceptable, but it seems that the work was written in a hurry and therefore it often contains formatting errors, typos and poor wording, which make it difficult to understand the work.

More specific questions below:

1. Line 59:The term carbon reduction means reducing emissions, it seems a more appropriate term here would be carbon offsets.
2. Line 110-119: Description is critically incomplete and unclear. According to your description, you take 3 points per 5 UGS views, but in figure 1 there are more than 15 points in each city. Do the sampling areas correspond to a square of 1 km2 or is there some area within 1 km2? It is also difficult to imagine that a whole square kilometer of a city has only one type of landscaping inside, so there should be descriptions of the size of the sites, criteria for assigning them to one type or another and a summary table with the total number of sites by type and city. In addition, the criterion for selecting a grid cell is not clear.
3. Line 152: Incorrect form of the publication reference - Conti et al., (2019) . In your reference list it is [21]
4. Line 163-165: There are no references to the literature cited.
5. Line 165-166: Figure 2. You identify three scenarios for the application of UGS, but it does not relate in any way to the types of UGS you mentioned when selecting representative sites (rows 110-119).  You need to indicate what proportion of your surveyed sites can be attributed to each of these. Without doing so, this may be a serious methodological flaw, as it may turn out that among your sites there are no sites corresponding to these scenarios and, in fact, these scenarios are characterised by a different set of species.
6. Line 212-215: No reference to the source of the climate data.
7. Line 219: You mention your previous work but do not reference it.
8. Line 226: Bring the size of the formula to the size of the formulas before it.
9. Line 254-257: It is not clear how the average for the city was calculated. Due to the fact that the methodology is not described, many questions arise at once:
   1. Is it an average increase on all sites in the city, averaged per square metre?
   2. Is it a square metre of UGS or the city in general?
   3. If it is averaged per square metre of city, what was the methodology for spatially extrapolating the survey sites to the entire city?
   4. Is it a consequence of tree condition, species composition, age or density of UGS in the city?
   5. Why are these metrics relevant at all?
10. Line 260-263: According to the methods section you distinguish the following types of UGS - parks, protective green spaces, attached green spaces, square green spaces and regional green spaces. But in line 260 you mention road green spaces, which you did not mention before.
11. Line 263-265. Figure 5: There is no explanation of what is shown with whiskers on the plot (IQR, min\max, CI). Figures 5a and 5b have labelles "abc", which is not explained in any way. Figures 5c and 5d use axis labels that have never been seen before in the text and should be explained in the figure caption (like POS, AGS etc)
12. Line 288-293. Figure 6: Despite one of the central roles in the whole work, these figures are absolutely unreadable. Yes, the clusters are clearly visible, but it is absolutely impossible to understand how cluster 5 in figure 6b is projected on the axes. Therefore, it is necessary to replace the 3d planes with 3 separate 2d planes to clearly understand the mutual arrangement of the clusters on the axes.
13. Line 291-293: Taking a group with a high CSE out of the analysis will significantly affect its result. From the explanation it is not clear whether this group was simply not shown, which is just strange, or it was not taken into account in the analysis at all. If the latter, then this is extremely incorrect. It turns out that the researchers assumed some "correct" clustering result in advance, and when they did not get it, they made an artificial manipulation of the data to get the result they expected. A detailed commentary from the authors on the necessity of such manipulation is required.
14. Line 294-303.It is not at all clear where all the information discussed in section 3.3 comes from. It may seem self-evident to the authors, but to someone who has read the paper several times, it is not. If I understand correctly, the results were obtained using the i-Tree Design model. What I can't understand is where the input data for this modelling came from, especially the contents of tables S5-S7. What raises a number of additional questions:
    1. What is the area of the described sites?
    2. Where in the text of the paper can I find information on what species occur in ZMA for waterbody and other scenarios?
    3. On what basis are these plant densities and sizes chosen in the "before" section of S5-S7?
    4. Certainly the modelling shows that the new set of species provides higher carbon sequestration, but you have written before that it is not just sequestration that is important, it is important to retain ornamental value and adaptability. Where can we see how these values have changed at the site, or has the selection been done in such a way that these values have not become worse? 
15. Line 303-306. Figure 7: You use the prefix kilo on the axis captions and then specify the dimension as kilograms. It would be more correct to drop the prefix and use tonnes of carbon instead of kilo kilograms.
16. Line 455-456: What do you understand by "ecological civilization"? Why does comparing one place with another indicate development? The thought requires clarification.
17. Line 462-464: Where can we see in your paper methodology and results of the CSE data obtained extrapolation to a global scale?

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript has been revised substantially in light of the suggestions given earlier. The manuscript can be considered for publication. However, there are a few minor corrections.

Check the Authority names added in the Abstract and present the Authority name in non-italic and scientific name in italic.

Check for typos throughout the manuscript, for example, space between sticky words.

In the Fig. 1, some words are presented in bold font and also underlines with red color dashed lines. If it is done for the emphasis, only bold font is enough, no need to underline the words.

In Fig. 1, also check the spelling in third point in the left panel. It should be Evaluation factors, I think.

In Fig. 3, give space between parameters and units in the x- and y-axis legends

Also present the figure captions more clearly. For example, Fig. 3 caption can be better presented as: Figure 3. Climate similarity. (a) a comparison of mean monthly precipitation and temperature, (b) a comparison of sunshine duration and growing season

Fig. 5 caption is not clear, it can be better presented

Fig. 6 and Fig. 7 are same or different? Check it in the final manuscript as it is not clear. Also check the figure captions and mention the figures clearly in the main text

Revise the manuscript before proceeding further.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have correctly and fully responded to all comments, the work has been significantly improved and is almost ready for publication after minor revisions noted below:

Line 15-16:  Carbon offsets refers to carbon that has been absorbed from the atmosphere and can be counted as compensation for someone's emissions. Obviously they should be increased rather than decreased, I think the sentence should be reworded.
Lines 117-122: The sentences are hard to read, I think some part is missing.
Lines 122-124: The definition of RGS is not clear. It should be expanded and specific examples added.
Line 339: Figure 7 is shown in answers, but disappeared in edited version of text, please check.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf