Homogenization of Urban Forests across the Subtropical Zones of China

Round 1

Reviewer 1 Report

The biological homogenization of urban green spaces is a topic of increasing concern among researchers, as it not only holds scientific significance but also impacts local landscapes and the well-being of residents. Therefore, this manuscript is both interesting and important. The study examines 19 case cities in the subtropical region of China, comparing the tree composition of wild forests and urban green spaces, quantifying the degree of homogenization, and analyzing the driving factors of homogenization in this region. I recommend minor revisions before publication.

1.       In abstract, Sabina chinensis should be italicized.

2.       L132，Why did you exclude studies focused on UFs dominated by planted vegetation or the data on natural vegetation? And could you give the concepts of planted vegetation and natural vegetation in UFs?

3.       Fig 2, Does Y-axis of both (a) and (b) mean species richness? Please make the Y-axis title and the units more clear.

4.        Please verify the slope in Figure 5d,e with L306 in the text, as there may be an error in labeling.

5.       L345-348, I don't understand these conclusions.

6.       L370, “We did not find a significant relationship between the similarity of tree species in UFs and differences in socioeconomic factors”. when explaining the lack of significant relationship between the similarity of tree species in UFs and differences in socioeconomic factors, it should be considered that the economic level of the case cities is relatively high, and there is no clear economic gradient formed, thus explaining the absence of statistical significance.

7.       In L380, the statement "Additionally, the lack of response of J to socioeconomic factors may indicate a relatively equitable distribution of green spaces among the studied cities" lacks evidence from this study. Therefore, it is suggested to remove this conclusion.

8.       In L433, the sentence “Thus, the biodiversity in urban forests also maintains a certain sense of locality” should be revised to reflect that "The removal of native species and the introduction of nonnative species may cause the loss of a sense of locality."

9.       In the Conclusions section (L491), the sentence "This means that the inequality between the socioeconomic factors has been enhanced due to biotic homogenization" should be removed, as the study did not focus on the equality of green spaces and did not provide solid evidence to support this statement.

10.   In the discussion section, it would be beneficial to include more discussion about Figure 4 to explore the reasons for the inconsistent homogenization performance of different diversity indices.

Author Response

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Reviewer 2 Report

1. In Introduction, the manuscript needs to expand on the benefits of urban forest. Huge amount of research has done on the area, and it can be justified of this study.

2. Relating to the justification of the study, specified statement would be helpful in the end of the Introduction.

3. The study's theme is interesting and the results of the study should be helpful for implementing in policy and practice/management as well. This importance may be described in the Introduction, and Discussion.

Author Response

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Reviewer 3 Report

This article aims to quantify the homogenization degree of tree species composition and diversity convergence within urban forests across the subtropical zones of China, finding a more pronounced homogenization effect at gradients with greater differences in climate and vegetation types. Among the conclusions it is pointed out that the introduction of non-native species can contribute to the complementarity of local species in ecological niches. It is a work that provides a different vision to the frequent studies that present a negative vision of alien species. The work is interesting and presents an adequate structure, which allows a fluid reading of all its sections, providing complete and concise information, understandable for a wide audience of readers. Before being accepted for publication, it would be recommendable that the authors pay attention to some aspects that I detail below:

-One of the aspects that most attracts my attention in this work is that it deals with "trees" and only a few species are mentioned throughout the text. And those that are mentioned also present nomenclature errors. This needs to be significantly improved as some bugs are not botanically acceptable. for example, in the abstract Sabina chinensis is mentioned, when the correct name is Juniperus chinensis; Acer mono is not a species that exists either, in any case Acer pictum ssp. bun. The list of Table S4 ambien presents numerous errors. The authors may not consider it important, but I can assure you that it is correct, since we all like to see that the principles of our research disciplines are considered rigorous and important.

2.2.1 Tree community data of urban forests: when the different Ufs types are listed, which type of Uf is traffic green species?

-Later in that chapter it is said that in addition to the field survey, references have been sought by the UF tree diversity index. It is not very clear why the information obtained from direct observations was supplemented with that existing in the literature.

-GDP is referred to in acronyms in various places throughout the text, but its full name must be defined the first time it is mentioned.

-The titles that are used in each one of the subsections of the Discussion are, at least, original. They better stick to the traditional, presenting what comes next

-Section 4.2. When the number of non-native species registered in the 19 cities of the study is mentioned, it is said that there are 1997 species. this figure is clearly wrong as it is higher than the 932 species registered in total, native and non-native. In the final paragraph of this section some introduced species are listed: S. babylonica, P. tabuliformis, P. orientalis, please write the genus completely. This terminology is used when the species has been mentioned previously, which is not the case.

Author Response

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