Assessment of the Temporal and Spatial Changes and Equity of Green Spaces in Guangzhou Central City Since the 21st Century

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

I am pleased to have been selected as a reviewer for an interesting paper such as yours, which highlights the conflict between the supply of green resources and the demands of densely populated economic centers, providing valuable insights for planners and policymakers to promote sustainable and equitable urban green space development.

The manuscript is well-structured, but I would still like to offer a few specific comments.

- In lines 39–40, you cite that “….between 2000 and 2014, GS coverage 39 continued to decline in both old and new urban areas of China's 98 most densely populated cities.” Could you cite additional authors who support this claim?

 

- In lines 51 to 53, you mention some general benefits of urban green spaces. I kindly suggest expanding this part of the introduction by providing a more detailed description of the ecological, social, psychological, and health-related benefits, supported by more specific examples. It is important to include this in the Introduction in order to highlight the significance of your research.

- Please include both the general and specific objectives of your research in the final paragraph of the Introduction.

- In subsection 2.1 Study Area and Data Sources, please provide a graphical representation of the study area in the form of a map.

I kindly ask the authors to supplement subsection 3.3. Comparative Analysis of Characteristics Across Urban Regions by providing additional explanation and context. Specifically, it would be helpful to:

-Include graphical representations (e.g., line charts or timelines) to better illustrate temporal changes in population, GDP, and green space indicators;

-Provide insights into the causes of green space loss in districts like Liwan and Haizhu, potentially linking these to urban development policies or land use changes;

-Incorporate a brief socio-demographic context, if data is available, to support discussion of spatial inequalities.

These additions would strengthen the analytical depth and enhance the overall clarity of the comparative regional analysis.

The Conclusion is well written, but there are a few comments I kindly ask you to consider in order to make the drawn conclusions clearer and better understood:

-Simplify complex sentences (reduce sentence length to improve readability and clarity);

-Include recommendations for future research, suggest concrete directions for further analysis, such as a more detailed study of intra-street differences in green space availability and

-Emphasize practical applications in order to clearly specify how the results can assist policymakers and urban planners.

 Best regards

Author Response

- In lines 39–40, you cite that “….between 2000 and 2014, GS coverage 39 continued to decline in both old and new urban areas of China's 98 most densely populated cities.” Could you cite additional authors who support this claim?

Thank you for pointing this out. We agree with this comment. Therefore, we have further reviewed the literature concerning the point that "between 2000 and 2014, GS coverage continued to decline in both old and new urban areas of China's 98 most densely populated cities" and added relevant references to better support this statement. These changes can be found on Page 2, paragraph1, line 42 .

- In lines 51 to 53, you mention some general benefits of urban green spaces. I kindly suggest expanding this part of the introduction by providing a more detailed description of the ecological, social, psychological, and health-related benefits, supported by more specific examples. It is important to include this in the Introduction in order to highlight the significance of your research.

Agree. We have, accordingly, expanded the description of the fundamental benefits of green space (GS) in the Introduction section. This expansion details these benefits across four key dimensions: ecological, psychological, and economic . These changes can be found on Page 2,  paragraph 2, lines 54-68 .

- Please include both the general and specific objectives of your research in the final paragraph of the Introduction.

 Thank you for pointing this out. We agree with this comment. Therefore, we have augmented the Introduction by explicitly stating the general and specific research objectives . These additions can be found on Pages 3-4, paragraphs 4-5, lines 129-146 .

- In subsection 2.1 Study Area and Data Sources, please provide a graphical representation of the study area in the form of a map.

 Thank you for pointing this out. We agree with this comment. Therefore, we have incorporated a location map characterizing the study area in Section 2.1 (Study Area and Data Sources). This addition can be found on Page 4, paragraph 3, lines 169-170 .

 

I kindly ask the authors to supplement subsection 3.3. Comparative Analysis of Characteristics Across Urban Regions by providing additional explanation and context. Specifically, it would be helpful to:

-Include graphical representations (e.g., line charts or timelines) to better illustrate temporal changes in population, GDP, and green space indicators;

Thank you for pointing this out. We agree with this comment. Therefore, we have only compared the data changes between two years and thus used box plots to contrast the data of these two years. This is also one of the limitations of this paper, which is also restricted by the availability of data. Hence, we will further supplement and revise it in future studies.This addition can be found on Page 4, paragraph 3, lines 169-170 .

-Provide insights into the causes of green space loss in districts like Liwan and Haizhu, potentially linking these to urban development policies or land use changes;

Thank you for bringing this to our attention; we fully concur with this observation. As such, we have added explanations regarding the factors behind the shrinking green spaces in districts like Liwan and Haizhu, and established connections between these factors and urban development policies as well as land use changes.

-Incorporate a brief socio-demographic context, if data is available, to support discussion of spatial inequalities.

These additions would strengthen the analytical depth and enhance the overall clarity of the comparative regional analysis.

Thank you for highlighting this point; we wholeheartedly agree with this observation. To strengthen our discussion on spatial inequality, we have therefore incorporated a brief sociodemographic context.

-Simplify complex sentences (reduce sentence length to improve readability and clarity);

Thank you for raising this issue; we fully endorse this feedback. Consequently, we have simplified convoluted sentences to enhance the text's readability and clarity.

-Include recommendations for future research, suggest concrete directions for further analysis, such as a more detailed study of intra-street differences in green space availability and

Thank you for highlighting this; we entirely agree with this comment. In response, we have expanded on recommendations for future research and conducted a more in-depth analysis of specific directions.

-Emphasize practical applications in order to clearly specify how the results can assist policymakers and urban planners.

Thank you for pointing this out; we are in full agreement with this comment. Accordingly, we have supplemented content to emphasize practical applications, with additional elaboration in the discussion section, thereby offering more specific recommendations to policymakers and urban planners.

 

Thank you again for all your suggestions. We have learnt a lot form your advice and we will try our best to improve our research ability in the future with your guidance.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript addresses the topic of green space (GS) equity in Guangzhou, which is undoubtedly of significant academic and policy relevance. However, in its current form, the study suffers from major conceptual and structural weaknesses that undermine its contribution to the field.

 

While the study aims to address the research gap at the micro (sub-district) scale, its current approach is primarily based on temporal comparisons and descriptive statistics. The analytical framework, choice of indicators, and methodological design appear to closely align with those found in prior studies. As such, the paper need a clearer articulation of its theoretical or methodological contributions to the literature on micro-scale green space equity.

 

The manuscript contains excessive repetition in its introduction, methodology, and results sections. Key concepts such as NDVI, Theil and Gini indices are repeatedly introduced without added value. Several figures and their textual descriptions are overly detailed yet poorly structured, leading to a fragmented narrative and a diminished reading experience. The discussion lacks a focused, problem-driven argument and instead reiterates known facts.

 

Specific Comments:

 

Line 11: The use of "Sub-districts (jiedao)" is awkward; the pinyin in parentheses is unnecessary and should be removed.

 

Lines 93–95: The sentence explaining the NDVI formula is repeated almost verbatim and should be streamlined into a single, clear definition.

 

Lines 135–153 (Data section): The exclusive use of GDP as a socioeconomic indicator is insufficient to assess environmental justice. Consider incorporating additional variables such as poverty rate, renter population ratio, or elderly population percentage—available via census or POI data—to develop a composite index of social vulnerability and better capture equity disparities.

 

Line 160: The equation (1) lacks proper variable alignment. Specifically, Agm should be explicitly defined as “per capita green space area.” Variable naming should be standardized throughout.

 

Figure 1: The color scheme is visually ineffective—text and legends are difficult to read. Increase font size and consider using black/monochrome for better contrast. Moreover, the results section offers only a single vague sentence to describe Figure 1. The relationship between LULC transitions and GS equity should be explained in greater detail.

 

Figures 4, 5, 7, and 8: These figures could be merged or significantly reduced. As this study centers on green space equity, it is unnecessary to present separate spatial distributions of GDP and NDVI unless they directly support a specific argument. The narrative should be streamlined around the GS equity storyline.

 

Line 229: The method for calculating NDVI change is vaguely described. Clarify whether the images were standardized or normalized, and specify whether temporal consistency in processing was ensured.

 

Line 262: There is a significant numerical error. The sentence states GDP increased from “40,800 million CNY to 11,600 million CNY.” The latter figure is likely missing a digit and should be corrected to 1,160,000 million CNY.

 

Line 294: Units are missing in the per capita GDP figure. Additionally, Zhuji Sub-district is mentioned without adequate explanation. The data presentation is disconnected from the narrative.

 

Lines 384–386: The NDVI spatial pattern is described in highly generic and repetitive language. Phrases such as “compact data clustering” and “stable superior vegetation” add no analytical value and should be removed or revised.

 

Lines 411–440 (Discussion): The manuscript remains at a descriptive level and does not explain why economic growth may lead to lower per capita green space. It is recommended to include a new subsection that interprets results through a theoretical lens—e.g., urban land economics or the “growth–ecology trade-off” model. A causal diagram showing how urbanization drives land-use changes, which in turn affect GS distribution and equity, could greatly improve analytical depth.

 

Lines 533–536 (Conclusion): The discussion of research limitations is overly superficial. Issues like accessibility-based metrics and housing prices are well-established concerns in this field. The authors should explain how they attempted to mitigate these limitations or why they were excluded.

 

Lines 449–492 (Policy Recommendations): The current policy suggestions are overly generic. Recommendations should be categorized into Planning strategies, design interventions, and governance mechanisms. It is also advisable to reference the "Three Dimensions of Environmental Justice" framework—distributional, procedural, and interactional justice—as a theoretical anchor for actionable equity policy. It is recommended to give specific suggestions that are applicable to China and have practical value, rather than just listing them in general and engaging in empty talk.

 

Author Response

Line 11: The use of "Sub-districts (jiedao)" is awkward; the pinyin in parentheses is unnecessary and should be removed.

 Thank you for pointing this out. We agree with this comment. Therefore, we have removed the parenthetical term "(jiedao)" following "sub-districts" . This change can be found on Page 1, Abstract, line 12 .

 

Lines 93–95: The sentence explaining the NDVI formula is repeated almost verbatim and should be streamlined into a single, clear definition.

 Agree. We have, accordingly, refined the explanation of the Normalized Difference Vegetation Index (NDVI) definition to enhance its completeness and fluency . This modification can be found on Page 3, paragraph 2, lines 108-112 .

 

Lines 135–153 (Data section): The exclusive use of GDP as a socioeconomic indicator is insufficient to assess environmental justice. Consider incorporating additional variables such as poverty rate, renter population ratio, or elderly population percentage—available via census or POI data—to develop a composite index of social vulnerability and better capture equity disparities.

 Agree. We have, accordingly, recognized that using GDP alone as a socioeconomic indicator in assessing environmental justice constitutes a limitation. We explicitly note that future research should develop a comprehensive social vulnerability index incorporating additional variables such as poverty rates, renter-occupied housing percentages, or elderly population proportions to better capture equity gaps. This discussion has been added on Page 19, paragraph 7, lines 659-669 .

 

 

Line 160: The equation (1) lacks proper variable alignment. Specifically, Agm should be explicitly defined as “per capita green space area.” Variable naming should be standardized throughout.

  Thank you for pointing this out. We agree with this comment. Therefore, we have standardized the descriptions and notation for multiple variables throughout the formulaic content . These adjustments can be found on Page 5, paragraph 6, lines 197-199 .

Figure 1: The color scheme is visually ineffective—text and legends are difficult to read. Increase font size and consider using black/monochrome for better contrast. Moreover, the results section offers only a single vague sentence to describe Figure 1. The relationship between LULC transitions and GS equity should be explained in greater detail.

Agree. We have, accordingly, optimized the figures' visual accessibility by modifying color schemes and implementing standardized typography (increased font sizes, black text for maximum contrast) . Furthermore, we expanded the discussion examining relationships between land use/land cover (LULC) transitions and green space equity . These modifications can be found on Page 6, paragraph 1, lines 216-226 .

 

Figures 4, 5, 7, and 8: These figures could be merged or significantly reduced. As this study centers on green space equity, it is unnecessary to present separate spatial distributions of GDP and NDVI unless they directly support a specific argument. The narrative should be streamlined around the GS equity storyline.

   Thank you for pointing this out. We agree with this comment. Therefore, we have strengthened the discussion by:

• Conducting a comparative analysis of GDP growth versus per capita GS area decline, providing empirical support for the paradoxical relationship between economic expansion and green space reduction;
• Explicitly aligning the observed NDVI increase with the "quantity-quality tradeoff" phenomenon (i.e., decreased GS coverage but improved vegetation quality) . These revisions can be found on Page 16, second paragraph, lines 495-508 and Page 19, paragraph 3, lines 635-641 .

 

 

Line 229: The method for calculating NDVI change is vaguely described. Clarify whether the images were standardized or normalized, and specify whether temporal consistency in processing was ensured.

Thank you for pointing this out. We agree with this comment. Therefore, we have explicitly stated that all imagery underwent standardized normalization procedures, while ensuring temporal consistency throughout the processing workflow . This clarification has been added on Page 8, paragraph 4, lines 268-270 .

 

 

Line 262: There is a significant numerical error. The sentence states GDP increased from “40,800 million CNY to 11,600 million CNY.” The latter figure is likely missing a digit and should be corrected to 1,160,000 million CNY.

  Agree. We have, accordingly, rectified the relevant data value after thorough re-examination, changing the original figure from 11,600 million to 1,160,000 million . This correction can be found on Page 10, paragraph 1, line 304 .

 

Line 294: Units are missing in the per capita GDP figure. Additionally, Zhuji Sub-district is mentioned without adequate explanation. The data presentation is disconnected from the narrative.

 Thank you for pointing this out. We agree with this comment. Therefore, we have:

• Supplemented the discussion of findings from Zhuji sub-district in Section 4.3
• Corrected the per capita GDP figure with proper unit annotation

These revisions can be found on Page 17, Section 4.3, lines 538-542 and Page 18, second paragraph, line 581 .

 

Lines 384–386: The NDVI spatial pattern is described in highly generic and repetitive language. Phrases such as “compact data clustering” and “stable superior vegetation” add no analytical value and should be removed or revised.

Thank you for pointing this out; we fully align with this comment. As a result, we have removed certain analytic terms and sentences that hold no substantial value.

 

Lines 411–440 (Discussion): The manuscript remains at a descriptive level and does not explain why economic growth may lead to lower per capita green space. It is recommended to include a new subsection that interprets results through a theoretical lens—e.g., urban land economics or the “growth–ecology trade-off” model. A causal diagram showing how urbanization drives land-use changes, which in turn affect GS distribution and equity, could greatly improve analytical depth.

Thank you for pointing this out. We agree with this comment. Therefore, we have established a dedicated subsection (4.3) to explicate the theoretical underpinnings and causal mechanisms governing the inverse relationship between economic growth and per capita green space reduction . This addition can be found on Page 17, paragraphs 2-3, lines 536-556 .

 

Lines 533–536 (Conclusion): The discussion of research limitations is overly superficial. Issues like accessibility-based metrics and housing prices are well-established concerns in this field. The authors should explain how they attempted to mitigate these limitations or why they were excluded.

Thank you for pointing this out; we are in complete agreement with this comment. In response, we have revised the section on the paper's limitations as per your suggestions, relocated it to the final paragraph of the discussion section, and expanded on it with detailed explanations.

 

 

Lines 449–492 (Policy Recommendations): The current policy suggestions are overly generic. Recommendations should be categorized into Planning strategies, design interventions, and governance mechanisms. It is also advisable to reference the "Three Dimensions of Environmental Justice" framework—distributional, procedural, and interactional justice—as a theoretical anchor for actionable equity policy. It is recommended to give specific suggestions that are applicable to China and have practical value, rather than just listing them in general and engaging in empty talk.

Thank you for pointing this out; we fully concur with this comment. In line with your suggestions, we have updated the content of the recommendations section and incorporated it into Section 4.1. Additionally, we have added the contributions of theories and methods regarding green space equity at the micro-scale to the conclusion section.

 

Thank you again for all your suggestions. We have learnt a lot form your advice and we will try our best to improve our research ability in the future with your guidance.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors This paper article investigates the inequality of GS availability across neighborhoods during the rapid urbanization process in Guangzhou's central urban area from 2000 to 2020.  This research  provides scientific evidence for urban planners and policymakers to promote equitable distribution and sustainable development of GS. The article  has a complete overall structure, clear logic, and standardized research design. It can provide important references for the research on the equity of urban green spaces and has certain theoretical value and practical significance. However, there are some suggestions as follows: 1. Line 534-537: Three limitations can be moved to the discussion section, each one should be elaborated in detail, such as factors such as housing prices and microclimate were not considered, but does not explain how these factors affect the distribution of green spaces. Future research directions can be further clarified.

2. The discussion mentions that GDP growth both promotes the improvement of green space quality and exacerbates the per capita shortage, but does not specifically analyze its mechanism of action. It is suggested to combine cases to enhance the explanatory power.

3. The basis and shortcomings of the indicators of green space equity selection should be described in detail, the differences and connections between the Theil index and the Gini index should also be described in detail.

Author Response

1. Line 534-537: Three limitations can be moved to the discussion section, each one should be elaborated in detail, such as factors such as housing prices and microclimate were not considered, but does not explain how these factors affect the distribution of green spaces. Future research directions can be further clarified.

Thank you for pointing this out; we fully agree with this comment. Following your suggestions, we have revised the section addressing the paper's limitations, moved it to the final paragraph of the discussion section, and expanded on it with detailed explanations.

2. The discussion mentions that GDP growth both promotes the improvement of green space quality and exacerbates the per capita shortage, but does not specifically analyze its mechanism of action. It is suggested to combine cases to enhance the explanatory power.

Agree. We have, accordingly, established a dedicated subsection (4.3) to examine the interaction mechanisms between GDP growth and green space (GS) metrics – specifically vegetation quality (NDVI-based) and per capita quantity . This addition can be found on Page 17, paragraphs 2-3, lines 536-556 .

3. The basis and shortcomings of the indicators of green space equity selection should be described in detail, the differences and connections between the Theil index and the Gini index should also be described in detail.

Thank you for pointing this out; we fully agree with this comment. As a result, we have updated Section 4.3 and supplemented your suggested content in its first paragraph. Additionally, we augmented the Conclusion with discussion regarding the foundational rationale and inherent limitations in selecting green space equity indicators . These modifications can be found on Page 19, paragraph 7, lines 659-669, Page 17-19, paragraph 4, lines 557-628 .

 

Thank you again for all your suggestions. We have learnt a lot form your advice and we will try our best to improve our research ability in the future with your guidance.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for the concise and thoughtful responses to all of my questions and suggestions. In its current form, I see no shortcomings in your work, so I will recommend to the editor that the paper be accepted in its present form."

Best regards

Reviewer 3 Report

Comments and Suggestions for Authors

 Accept in present form