Urban Forest Health Under Rapid Urbanization: Spatiotemporal Patterns and Driving Mechanisms from the Chang–Zhu–Tan Green Heart Area

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper provides a comprehensive investigation into the influencing factors of forest health within the Changsha-Zhuzhou-Xiangtan urban agglomeration in central China. The study is well-structured, employing appropriate methodologies, and its conclusions offer valuable insights for urban planning and the sustainable development of urban green spaces. Nevertheless, several areas could be enhanced to further strengthen the manuscript:

(1) In the introduction, while the authors underscore the importance of forest health assessment, a clear articulation of the existing academic gaps in this research area is not provided. A more conventional approach would involve first identifying the specific research lacunae, which would then logically lead to the novel contributions of the present study.

(2) It is noted that in Figure 1, both a compass and latitude/longitude grids are used to indicate direction. Given that the graticule already sufficiently denotes orientation, retaining only the latitude and longitude would be more concise and adhere to standard cartographic practice.

(3) In Section 2.3.6, a high degree of correlation likely exists among the variables of population density (X10), GDP (X11), and nighttime lights (X12). Although the geographic detector model is robust to multicollinearity, this raises an issue of interpretation. Specifically, if the spatial patterns of population density (X10) and GDP (X11) were generated with the assistance of the nighttime lights (X12) data, these three variables could essentially be considered as a single composite indicator. It is recommended that the authors first clarify whether the population density and GDP datasets were derived from the nighttime lights data. If so, retaining only one of these variables would be advisable. Furthermore, as the paper's title refers to "rapid urbanization," the corresponding independent variables (X) should explicitly reflect this dynamic process.

(4) Abbreviations are present in Figures 3 and 4. To enhance the readability of these figures, it is recommended that the full names of these abbreviations be provided in the figure captions.

(5) Approximately two-thirds of the cited literature is not from the last five years. It is suggested that the authors incorporate more recent publications to ensure the literature review is current and reflects the state-of-the-art in the field.

(6) In contemporary studies of influencing factors, the prevailing trend is to include a greater number of manageable, policy-relevant variables. This approach can yield more actionable findings for policymakers. The current results of this paper are predominantly driven by natural factors. However, it is difficult for urban planners and managers to alter topography and elevation to improve urban forest health. Therefore, should the authors plan further research on this topic, it is highly recommended that they consider incorporating more controllable factors, such as those related to policy and management interventions.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

One of the most outstanding manuscripts of an outstanding research study that I have ever reviewed. Excellent and complete Abstract and Introduction. The Materials and Methods section as well as the Results section were beyond reproach. The statistical tests, results, and interpretations were all solid and appropriate. An excellent Discussion section and I appreciated the fact that the author/s directly addressed the limitations of the study. Conclusion was succinct and carried the important messages. Cited references were appropriate and complete.

My only (2) suggestions are so minor I am a bit embarrassed for mentioning them. First, on line 194, the third word should read "...The..." Second, Figure 5 would benefit from a color key to help the reader make sense of the figures.

My compliments to the author/s for an outstanding piece of scientific work that will help regions/communities better understand and manage their forests, urban and peri-urban.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for inviting me to review the manuscript entitled
“Urban Forest Health under Rapid Urbanization: Spatiotemporal Patterns and Driving Mechanisms from the Chang-Zhu-Tan Green Heart Area”
submitted to Sustainability.

This manuscript addresses a critical theme of ecological importance, assessing how rapid urbanization affects urban forest health in an ecologically significant region through integrating multi-source remote sensing data with a composite forest health index and advanced spatial analysis using the optimal parameter geographic detector (OPGD) model. The time series analysis from 2005 to 2023 and the driving factor exploration offer valuable insights into complex ecological dynamics under anthropogenic pressures.

While the study is timely and relevant with a sound conceptual framework, substantial improvements are necessary in methodological clarity, presentation of results, and deeper critical discussion before it is suitable for publication. Therefore, I recommend major revision. Detailed comments follow.

Major comments

Abstract

The abstract is descriptive but could be more concise and highlight the novelty and key quantitative outcomes more clearly. Please explicitly state the main findings and the benefits of applying the OPGD model in this context. Also, define all acronyms (e.g., OPGD, FHI) when first mentioned.

Introduction

The background is thorough but somewhat diffuse. Please enhance the clarity by explicitly stating the research gap addressed and clearly listing the study’s objectives or hypotheses. A numbered or bulleted list of objectives would improve reader orientation.

Materials and Methods – Data Sources and Processing (Section 2.2)

The multisource data integration is described, but more detail is needed on how spatial heterogeneity in data resolutions was addressed, particularly aligning 28.6 m remote sensing data with 1000 m socioeconomic datasets, to avoid potential biases.

Materials and Methods – Forest Health Assessment and OPGD Model (Sections 2.3 & 2.3.6)

The construction of the forest health index (FHI), including normalization, factor analysis, weighting, and classification thresholds, should be more transparently explained, with inclusion of factor loadings and validation metrics.

The OPGD methodology and parameter optimization process is briefly described; elaborating with a conceptual workflow or schematic figure would enhance reproducibility and understanding.

Results – Spatiotemporal Dynamics of Forest Health (Sections 3.2 & 3.3)

Figures illustrating temporal trends and spatial patterns are informative but require improved labeling, inclusion of units, and enhanced legibility (larger fonts, clearer legends, and north arrows on maps).

Consider providing summary statistics such as annual rates of change or variation in health indices alongside maps to better quantify trends.

Results – Driving Factor Analysis (Section 3.4)

The identification of dominant drivers and interaction effects is well presented. However, the discussion lacks critical examination of the temporal stability of these drivers and possible multicollinearity.

Please clarify how spatial scale and discretization choices impact these results and if sensitivity analysis was performed.

Discussion and Conclusion

The discussion relates findings to urbanization impacts and ecological restoration but should be expanded to critically address study limitations, including data resolution constraints, exclusion of certain ecological indicators (e.g., understory vegetation), and the static nature of socioeconomic data.

The conclusion would benefit from a clearer statement of actionable management recommendations and future research directions.

 

Minor Comments

Abstract

Define all acronyms at first use to enhance accessibility.

Figures

Improve figure clarity by enlarging font sizes, adding north arrows and scale bars to all map figures, and ensuring color schemes are distinguishable for colorblind readers.

Tables

Add abbreviations explanations in captions; consider moving extensive or highly detailed tables to supplementary materials to improve readability.

References

Uniformly format references according to journal style and include DOIs where missing.

Language and Grammar

Perform careful proofreading to correct minor grammatical errors and improve sentence fluency.

Terminology

Clearly define technical terms and acronyms (e.g., LPI, SHDI, CONTAG) upon first mention in the text.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The quality of this paper has been greatly improved compared to the previous version; however, some issues regarding the figures need further attention:

Figure 6:

• The caption refers to "FH," but the figure itself uses "FHI." Please check for consistency.

• The legend is divided into four categories, but the corresponding FHI range for each category is not specified. It is recommended to add this information to the legend for clarity.

• Additionally, the wording in the caption is a bit inconsistent; it uses an abbreviation in the first half and the full term in the second. Please ensure the terminology is uniform.

Figure 10:

• I suggest adding the explanations for what X1-X12 represent (currently in the main text) as a note in the figure caption. This would make the results presented in the figure more intuitive.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Accept.

Author Response

We sincerely appreciate your detailed and insightful comments on our manuscript. Your valuable suggestions have been instrumental in helping us identify areas for improvement, refine our analytical methods, and enhance the overall quality and clarity of our research. Whether regarding terminology consistency, chart readability, or logical coherence, your feedback has prompted us to re-examine key aspects of the study with greater rigor, ultimately improving the manuscript’s rigor and readability. We deeply appreciate the time and expertise you have invested in evaluating our work; your insights have been instrumental in raising the standards of this research. Once again, we sincerely thank you for your valuable contributions to advancing this research.