Spatiotemporal Variations in Carbon Sources and Sinks in National Park Ecosystem and the Impact of Tourism
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Overall the topic is interesting, carbon source and sink are interesting studies and a perspective from national parks is critical. The paper is well written and clearly presented. The literature review is sound and the methods used are reasonable.
The manuscript can benefit from the following:
1. The conclusion is rather short, it could highlight the theoretical contribution of the study.
2. The study is case sensitive, are the results applicable to other case areas?
3. What is tourism development situation in the study area Huangshan?
4. Improve some expression in English language.
5. Add more up to date literate
Comments on the Quality of English Language
Minor editing is needed as there are some mistakes in grammar and expression.
Author Response
Comments 1: The conclusion is rather short, it could highlight the theoretical contribution of the study.
Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we have reorganised the conclusions of the study by stating the innovativeness of the study, detailing the main findings, and adding an overview of the theoretical significance, the limitations, and an overview of further research. Page 19, lines 625-667 in the revised manuscript this change can be found, which was marked in red.
Comments 2: The study is case sensitive, are the results applicable to other case areas?
Response 2: Thank you for this comment. The study on the carbon sources and sinks of national parks is exploratory and inspiring, and can be applied to other case areas. We also want to research different types of national parks or nature reserves in the future. Page 19, lines 664-667 in the revised manuscript the explanation can be found, which was marked in red.
Comments 3: What is tourism development situation in the study area Huangshan?
Response 3: Thank you for this comment. Huangshan is the origin of modern tourism in China and was one of the first scenic spots in China to be awarded both World Cultural and Natural Heritage and World Geopark status. Huangshan is also the first region in the World-Class Outstanding Destination Scenic Area and the first to earn recognition as an Observational Area for Sustainable Tourism Development. It remains the solitary representative from the Asia-Pacific region contributing to the formulation of the Global Destination Sustainable Tourism Standard. In 2017, Huangshan established friendly cooperation with Jungfrau in Switzerland and Yosemite in the United States, thereby further enhancing its international reach. In recent years, Huangshan has been proactively developing new sources of tourism-related economic growth. It has fully leveraged the multiple advantages of culture, tourism, nature and ecology, addressing international, regional and neighbouring markets, reshaping the tourism pattern with a regionally integrated approach and accelerating the construction of an ecological, international and world-class tourist destination. The content about the tourism development situation in Huangshan has been added to page 4, the first paragraph marked in red in the revised manuscript.
Comments 4: Improve some expression in English language.
Response 4: Thank you for pointing this out. We agree with this comment. As non-native English speakers, we recognise that errors in grammar and expression are unavoidable. We have therefore read the manuscript carefully, corrected the errors and made the necessary improvements.
Comments 5: Add more up to date literate.
Response 5: Thank you for pointing this out. We agree with this comment. We have added up-to-date literature on the study area, resulting in a total of 83 references in the revised manuscript, an increase from the previous 61. The revised manuscript has been updated to reflect research progress and relevant content marked in red.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
The manuscript is well written and I would suggest that the author improve it as follows.
1.I would suggest adding the literature review following the introduction part to show the recent progress in the field and to position the academic significance of the research in the field.
2.I would suggest that the conclusion part is detailed in the main conclusion,policy implication,limitation and further research.
Author Response
Comments 1: I would suggest adding the literature review following the introduction part to show the recent progress in the field and to position the academic significance of the research in the field.
Response 1: Thank you for pointing this out. We agree with this comment. We have added up-to-date literature following the introduction part, which include recent advances in the field of research, as well as the application and validation of research methodologies, theoretical foundations and the significance of the study. The revised manuscript has been updated to reflect research progress and relevant content marked in red.
Comments 2: I would suggest that the conclusion part is detailed in the main conclusion, policy implication, limitation and further research.
Response 2: Thank you for pointing this out. We agree with this comment. We have reorganised the conclusions, and provided a comprehensive overview of the main conclusion, policy implication, limitation and further research. Page 19, lines 625-667 in the revised manuscript this change can be found, which was marked in red.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
The article explores an important issue of sustainable development, particularly its application in urban environments, demonstrating strong academic and practical value. Additionally, the research introduces the "Impact of Tourism" aspect, which is an innovative point of the study. It employs a combination of quantitative and qualitative methods, with rich data sources and diverse analysis techniques, supporting the reliability and generalizability of the research findings. However, the study also has the following issues and suggestions, and a major revision is recommended.
1.The keyword "Impact of Tourism" mentioned in the title is not thoroughly addressed in the overall content of the study. The connection and integration between different sections of the article are not tight.
2.The description of the research's originality is not sufficiently prominent. It is suggested to elaborate on the research's innovation in conjunction with the introduction section of the article.
3.It is suggested that the author enhance the literature review by including references to key studies, particularly recent research in the field, to strengthen the theoretical foundation of the study.
4.The discussion section should be expanded to more thoroughly explain the research results by integrating existing theoretical frameworks and literature, which will help improve the academic contribution and practical value of the research. Additionally, it is recommended to include the limitations of the study and prospects for future research in the discussion section.
5.The conclusion section is too simple and fails to provide a sufficiently clear and comprehensive overview of the main findings. The authors are advised to reorganize this section.
6.The scale of the map of China in Figure 1 is distorted. Please revise it.
7.The titles of Figures 5, 6, and 7 are problematic. They should have a main title, followed by sub-titles (a) and (b). Please check and revise accordingly.
Author Response
Comments 1: The keyword "Impact of Tourism" mentioned in the title is not thoroughly addressed in the overall content of the study. The connection and integration between different sections of the article are not tight.
Response 1: Thank you for pointing this out. We agree with this comment. We have refined the internal logic of the content of each part of the article and made major revisions to the overall content of the manuscript in order to enhance the coherence and informational value of the article. These revisions are marked in red in the manuscript. Regarding “Impact of Tourism”, we have expanded the discussion to provide a more detailed explanation based on the study's findings. In particular, a new subsection “4.2 Effect of human activity factors on NEP changes” has been added to illustrate the impacts of human activities, including tourism, on NEP changes in ecosystems, which can be found on pages 15-16, lines 523-537. We have also expanded the conclusions to include a section on the impact of tourism.
Comments 2: The description of the research's originality is not sufficiently prominent. It is suggested to elaborate on the research's innovation in conjunction with the introduction section of the article.
Response 2: Thank you for pointing this out. We agree with this comment. We have combined the contents of the introduction by integrating the existing literature, and found that there is still a lack of systematic research on whether the natural ecosystems of national parks are carbon sinks or carbon sources, while this study focuses on the carbon sources and sinks in the ecosystems of national parks. This is a crucial foundation for the study and represents a significant innovation. Page 2, lines 71-79 in the revised manuscript the explanation can be found.
Comments 3: It is suggested that the author enhance the literature review by including references to key studies, particularly recent research in the field, to strengthen the theoretical foundation of the study.
Response 3: Thank you for pointing this out. We agree with this comment. We have added up-to-date literature on the study area, resulting in a total of 83 references in the revised manuscript, an increase from the previous 61. The revised manuscript has been updated to reflect new additions and relevant content marked in red.
Comments 4: The discussion section should be expanded to more thoroughly explain the research results by integrating existing theoretical frameworks and literature, which will help improve the academic contribution and practical value of the research. Additionally, it is recommended to include the limitations of the study and prospects for future research in the discussion section.
Response 4: Thank you for this comment. We agree with this comment. We have expanded the discussion, including a new subsection and new figures, and added some new paragraphs to explain the findings in greater detail. All changes and additions are marked in red in the revised manuscript. Furthermore, we have added the “include the limitations of the study and prospects for future research” mentioned in the comments to the conclusion part, taking into account the rationality of the structure.
Comments 5: The conclusion section is too simple and fails to provide a sufficiently clear and comprehensive overview of the main findings. The authors are advised to reorganize this section.
Response 5: Thank you for pointing this out. We agree with this comment. We have reorganised the conclusions, and provided a comprehensive overview of the main conclusion, policy implication, limitation and further research. Page 19, lines 625-667 in the revised manuscript this change can be found, which was marked in red.
Comments 6: The scale of the map of China in Figure 1 is distorted. Please revise it.
Response 6: Thank you for pointing this out. Changes have been made to the Figure 1 in the revised manuscript and the changes can be found on page 4.
Comments 7: The titles of Figures 5, 6, and 7 are problematic. They should have a main title, followed by sub-titles (a) and (b). Please check and revise accordingly.
Response 7: Thank you for pointing this out. The title of the Figure 5, 6, and 7 has been changed in the revised manuscript and the changes can be found on page 11 and page 13.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for Authors
The authors presented an interesting study of the dependence of changes in carbon absorption on long-term, seasonal and altitude dynamics. The study is relevant and interesting and can be tested and scaled up to other territories, not only reserves and national parks. For example, the effect of measures to combat desertification on the carbon balance is of particular interest.
The dynamics of absorption and emission of carbon dioxide in ecosystems has complex dependencies and relationships, judging by the assessment of biomass growth. Carbon emission control usually considers industrial facilities and accounting for the contribution of carbon emission in finished products - the carbon footprint. It is debatable that the methodology for achieving carbon neutrality can be used directly to assess different types of ecosystems; when maintaining their condition, technologies with carbon dioxide emission are needed, when utilizing biomass, clearing water bodies, sanitary cutting of woody vegetation and shrubs. It is known that seasonal processes of growth and destruction of biomass - rotting, swamping can change the balance from carbon dioxide absorption to its active emission. The main focus is still on developing a methodology for determining local carbon pools in various components of phytobiota and in the soil, as well as creating a database on the current carbon content in forest, wetland and other ecosystems and comparing them with global assessment methods.
The Huangshan study area is extremely popular, the recreational load is more than 1.5 million to 4.0 million visitors annually by 2023. Mountains with a height of up to 1 km, a climate of high humidity, in summer precipitation can exceed 300 mm. In winter, there are snowfalls. The altitudinal distribution of vegetation is characteristic.
Note:
1. In the article, the authors use “Natural condition”: “TEMP：temperature/° ”, “PRE：precipitation/mm” and “SRI：solar radiation intensity/Wm2” (lines 197-198, “Table 3. Potential factors of net ecosystem productivity”). It is necessary to justify the choice of these indicators.
2. In addition to (Figure 4a), a zoning map of the study area by vegetation type is needed, if possible, taking into account linear anthropogenic transformation, since there are more than 50 kilometers of pedestrian paths providing access to scenic spots for visitors and staff of the facilities. It is known that high-mountain tourist sites are served by pedestrian delivery, which significantly reduces the transport load. Such a high anthropogenic load can also be a factor influencing carbon emissions, taking into account the sources of input.
4. In the article, the authors use two measures of anthropogenic impact assessment – ​​“Human activity” - “LC: land cover Land cover” and “POI: scenic spot tourism” (lines 197-198, “Table 3. Potential factors of net ecosystem productivity”). It is also necessary to justify the choice of these indicators.
5. The information needs to be detailed, lines 219-220: “In contrast, in summer and winter, the ecosystem showed a carbon source characteristic, with a higher carbon source contribution rate in summer (approximately 91.1%) than in winter (approximately 83.0%).”
6. The phrase requires clarification, lines 337-338: “Meanwhile, POI had a strong interaction with all factors except TEM. It can be concluded that tourism activities at this stage had the strongest driving effects.”
Comments for author File: Comments.pdf
Author Response
Comments 1: In the article, the authors use “Natural condition”: “TEMP：temperature/° ”, “PRE：precipitation/mm” and “SRI：solar radiation intensity/Wm2” (lines 197-198, “Table 3. Potential factors of net ecosystem productivity”). It is necessary to justify the choice of these indicators.
Response 1: Thank you for pointing this out. We agree with this comment. We reviewed some of the relevant literature before selecting the impact factors, and of the existing studies, temperature, precipitation, and solar radiation intensity have been identified as the most important natural factors that influence the change of NEP. So, we select them as Natural condition factors. Page 6, lines 227-229 in the revised manuscript the explanation can be found, which was marked in red.
Comments 2: In addition to (Figure 4a), a zoning map of the study area by vegetation type is needed, if possible, taking into account linear anthropogenic transformation, since there are more than 50 kilometers of pedestrian paths providing access to scenic spots for visitors and staff of the facilities. It is known that high-mountain tourist sites are served by pedestrian delivery, which significantly reduces the transport load. Such a high anthropogenic load can also be a factor influencing carbon emissions, taking into account the sources of input.
Response 2: Thank you for pointing this out. Through the field survey, the distribution of vegetation types in the Huangshan Mountains also varied roughly along the elevation gradient, which is closer to the results of the reclassification according to elevation in Figure 4a. To enhance the clarity of the results, we have provided a detailed specification and explanation on page 9, lines 289-297, regarding the reclassification of the Huangshan Mountains according to elevation, which involved the integration of the distribution of vegetation types and soil types. Furthermore, with regard to the anthropogenic impacts on pedestrian paths and high-mountain tourist sites, as outlined in the comments, we conducted a functional zoning of the Huangshan National Park (Figure 8) and discussed the changes in NEP in areas with different intensities of tourism activities. Additionally, we investigated the influence of tourism activities on the CSS of ecosystem. Page 16, lines 540-550 in the revised manuscript the explanation can be found, which was marked in red.
Comments 3: In the article, the authors use two measures of anthropogenic impact assessment – ​​“Human activity” - “LC: land cover Land cover” and “POI: scenic spot tourism” (lines 197-198, “Table 3. Potential factors of net ecosystem productivity”). It is also necessary to justify the choice of these indicators.
Response 3: Thank you for pointing this out. We agree with this comment. Among anthropogenic factors, land cover changes can reflect the change in land use type caused by human activities on the one hand, and the change in forest cover area caused by artificial afforestation on the other hand. As a popular tourist destination, Huangshan National Park attracts millions of tourists annually. The development of tourism activities is an important function, while the scenic spot tourism POI can reflect the development of tourism as well as the carrying capacity, which in turn can characterise the impact of tourism activities on the NEP. So, we select them as Human activity factors. Page 6, lines 229-235 in the revised manuscript the explanation can be found, which was marked in red.
Comments 4: The information needs to be detailed, lines 219-220: “In contrast, in summer and winter, the ecosystem showed a carbon source characteristic, with a higher carbon source contribution rate in summer (approximately 91.1%) than in winter (approximately 83.0%).”
Response 4: Thank you for pointing this out. We agree with this comment. Combining Figure 3a and Figure 3b gives a more intuitive understanding of what this sentence is trying to convey. We have modified this sentence and made its expression clearer and more explicit, pages 7-8, lines 263-272 in the revised manuscript the change can be found.
Comments 5: The phrase requires clarification, lines 337-338: “Meanwhile, POI had a strong interaction with all factors except TEM. It can be concluded that tourism activities at this stage had the strongest driving effects.”
Response 5: Thank you for pointing this out. We agree with this comment. There was a small error in this sentence, and we have modified the expression. The strength of the interaction between POI and all the other factors except TEM is greater. Consequently, it is considered that the degree of influence of POI is stronger at this stage. Pages 12-13, lines 404-408 in the revised manuscript the change can be found.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for Authors
Thank you for your diligent revisions. Your efforts have resolved most of the issues, and the quality of the article has greatly improved. However, I would like to suggest further modifications on the following points:
1.Originality of the article
The current revisions primarily involve the addition of references and the identification of gaps in existing research. However, the originality of your study is not directly addressed. I recommend providing a more explicit explanation of the innovation in your research to clarify the study’s theme and value for the readers.
2.Research limitations and future research
The discussion of research limitations and future research has been moved to the conclusion section. However, these points should ideally be included in the discussion section, where a more objective evaluation of the research findings can be made. Additionally, the content on research limitations and future directions is currently insufficient and needs to be expanded.
I hope these suggestions will help you in further refining your manuscript.
Author Response
Comments 1: Originality of the article--The current revisions primarily involve the addition of references and the identification of gaps in existing research. However, the originality of your study is not directly addressed. I recommend providing a more explicit explanation of the innovation in your research to clarify the study’s theme and value for the readers.
Response 1: Thank you for pointing this out. We provide a more explicit explanation of the innovation of our study, which can be found on page 3, lines 111-121.
Comments 2: Research limitations and future research--The discussion of research limitations and future research has been moved to the conclusion section. However, these points should ideally be included in the discussion section, where a more objective evaluation of the research findings can be made. Additionally, the content on research limitations and future directions is currently insufficient and needs to be expanded.
Response 2: Thank you for pointing this out. We have moved the part of research limitations and future research to the Discussion and expanded it. Page 15, lines 507-517, and page 19, lines 648-654 in the revised manuscript the explanation can be found.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for Authors
The authors have significantly improved the manuscript. The information has been updated for a better understanding.
Note: it is necessary to reflect the impact of COVID-2019 on the assessment of the carbon footprint.
Author Response
Comments 1: It is necessary to reflect the impact of COVID-2019 on the assessment of the carbon footprint.
Response 1: Thank you for pointing this out. The effect of Covid-19 on carbon sources and sinks in national park ecosystems is not obvious, the relevant additions can be found in page 18, lines 630-635, which was marked in red.
Author Response File: Author Response.pdf
