Ecological Carrying Capacity and Driving Factors of the Source Region of the Yellow River in China over the Past 30 Years

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This research addresses an urgent environmental problem regarding the ECC of the Source Region of the Yellow River, basic to the knowing of ecological processes happening in the Qinghai-Tibet Plateau. Considering it should serve as an ecological shield, the work is quite opportune and relevant against the current upsurge of ecological degradation and changing climatic conditions. Application of the Ecological Footprint method is praiseworthy, mainly because it is among the most researched and applied methods of assessing ECC. Elaborating articulately on the advantages of this particular method, such as simplicity and good operability, this paper develops a greater effectiveness in the application. Additionally, the application of principal component analysis in identifying driving factors that influence ECC introduces a layer of statistical rigorousness, adding to the credibility of the findings. This paper has given the necessary review of existing literature, which tremendously highlights lacunae in the current research, especially on the Source Region of the Yellow River. It provides a sound foundation for this study by justifying the need and indicating precisely how this research furthers ecological studies. The identification of social factors, such as urban population growth and per capita, as primary drivers of ECC is particularly insightful. Policymakers can benefit from this study, which highlights the impact of socioeconomic issues on ecological conditions and emphasizes the need for sustainable development policies to take these aspects into account in order to improve ecological resilience. The reader is guided through the goal and significance of the study by the paper's clear statements of its objectives and research questions. This clarity makes it easier to comprehend the research's motivations and any possible ramifications for ecological management. Nonetheless, I believe that the subjectivity of the ECC index system's construction is a problem that the article inherits. Because biased conclusions may result from subjective decisions made during the index selection process, this could compromise the validity of the results.

However, in my opinion, the paper inherits a weakness in the subjectivity of the building of the ECC index system. This may undermine the reliability of the results because subjective choices in the selection of the indexes may lead to biased conclusions. Such a weakness could be strengthened by a more objective approach or a sensitivity analysis. The research presents the ecological conditions of the Source Region, but, as the authors mention in the paper, previous literature was based on a single county or one grassland, which may not be representative enough to understand the complex ecological dynamics in the entire source region. This paper could therefore have done with an extensive multi-ecological indicators approach, their interactions, and more. The paper refers to the lack of quantification in assessment, which is a very critical area in ecological research. Without appropriate quantification, the whole finding may be weakened. Incorporating some quantitative metrics about ecosystem services that would reflect a finer degree of ecological health would further improve this analysis. The emphasis on static evaluation methods could not capture the dynamic nature of changes in ecology over time. This trend should go towards more dynamic modelling approaches, like time-series analysis or simulation models that can strengthen the analysis by depicting future trends.

From these strengths and weaknesses, it then follows that this paper has the potential for publication, provided major revisions are made. The plus points-an appropriate topic, methodological soundness, and identification of key drivers-provide a good core for the paper. It is, however, necessary to eliminate its weaknesses: subjectivity and limited scope, combined with quality of language used, because these will prevent it from reaching the publication threshold.

Comments on the Quality of English Language

The english is fine to me

Author Response

Comments 1:Nonetheless, I believe that the subjectivity of the ECC index system's construction is a problem that the article inherits. Because biased conclusions may result from subjective decisions made during the index selection process, this could compromise the validity of the results.However, in my opinion, the paper inherits a weakness in the subjectivity of the building of the ECC index system. This may undermine the reliability of the results because subjective choices in the selection of the indexes may lead to biased conclusions.This paper could therefore have done with an extensive multi-ecological indicators approach, their interactions, and more. The paper refers to the lack of quantification in assessment, which is a very critical area in ecological research. Without appropriate quantification, the whole finding may be weakened.

Response 1:Thank you for pointing this out. We agree with this comment.We have a certain degree of subjectivity in selecting the drivers of ecological carrying capacity, which may cause bias in the research results, and we have not selected indicators that can be quantified. The source area of the Yellow River is the ecological barrier of the Qinghai-Tibet Plateau of China. In screening the driving factors, after sorting out the research results on the driving factors of ecological carrying capacity, we screened mainly the social factors that have a greater impact on ecological carrying capacity, and also screened out the representative natural factors in combination with the geographic location of the source area of the Yellow River. In terms of model selection, we have not yet considered a more appropriate method, and there is a lack of experience.

Reviewer 2 Report

Comments and Suggestions for Authors

This is a well-done analysis of the ecological carrying capacity  in  the counties of the Chinese source region of the Yellow River in the period between 1990 and 2020. It starts with the relevant statement that "the status of regional ECC is one of the important bases for planning a country's socio-economic development and adopting appropriate strategies and measures for environmental issues." What one, however, misses is, on the basis of the analysis of these thirty years, the discussion about "the appropriate strategies and measures"  and  (possibly positive)  developments in the present situation and in the future  what one expects from those given statements at the beginning of the paper. This should certainly be added to make the article not only important for the region of the Yellow River, but also with regard to situations in international respect.

Author Response

Comments 1：What one, however, misses is, on the basis of the analysis of these thirty years, the discussion about "the appropriate strategies and measures"  and  (possibly positive)  developments in the present situation and in the future  what one expects from those given statements at the beginning of the paper. This should certainly be added to make the article not only important for the region of the Yellow River, but also with regard to situations in international respect.

Response 1：Agree.Greetings to the esteemed reviewers. Firstly, thank you very much for recognising our work and for your suggestions on this paper. We agree with you that we have made textual additions and changes at the end of the second paragraph in the preface to ensure greater compliance with journal publication requirements.

Reviewer 3 Report

Comments and Suggestions for Authors

The objective of the study is to examine the spatial and temporal alterations in the ecological carrying capacity (ECC) of the source region of the Yellow River (SRYR) on the Qinghai-Tibet Plateau in China, and to identify the principal factors influencing this phenomenon.

The following objectives were addressed in the study:

1. The analysis of spatial and temporal land use changes is a key objective of the study. The researchers conducted an analysis of the spatial and temporal land use changes in the SRYR over the past 30 years (from 1990 to 2020).

2. Determination of the absolute ecological carrying capacity (AECC). The absolute ecological capacity (AECC) of pastures and forests in the SRYR was determined, as was the overall ECC of the region.

3. The researchers also examined the spatial heterogeneity of AECC in SRYR, as well as any changes that may have occurred over the past three decades.

4. Finally, the impact of specific landscape indicators, including SPLIT, PARAMN, and COHESION, on ECC in SRYR was evaluated.

In conclusion, the text offers new insights into the dynamics of the SRYR's ECC, which constitutes a significant contribution to the study of ecological sustainability in mountainous regions. The findings can inform the development of strategies to manage ECC and ensure the sustainable development of the region.

 The list of references is comprehensive and meets the standards required for academic publication. The article is written in a clear and accessible style.

 

Dear Authors, in the course of reading and analysing your article, I have formulated the following comments and questions.

1. In the introduction, it is essential to delineate the rationale behind the selection of SRYR as the subject of the study. On what grounds did the authors select this particular?

2. In the text, when referencing Figure 1, it is essential to provide a clear and concise explanation of the various colored areas depicted on the map. What do these symbols represent?

3. In Table 1, the column headings should be written in uppercase.

4. The first sentence of paragraph 2.2 requires further clarification. Please provide justification for the selection of a time step of five years. A rationale must be provided.

5. The construction of Table 2 is such that the relationship between the various elements is not immediately apparent. It is recommended that the item in question be removed from the article and that the text be incorporated into the body of paragraph 2.2.

6. It would be preferable to use the term 'Equation' in place of 'Formula'.

7. Tables 3 and 4 require elucidation and a conclusion. What is the intended meaning for the reader upon examination of these tables?

8. It would be beneficial to ascertain whether it is imperative to include the same reference to the program in the captions to the figures. I believe that a single initial mention is sufficient.

9. It would be beneficial to provide a more detailed explanation of the social factors presented in conclusion 5.

Author Response

Comments 1: In the introduction, it is essential to delineate the rationale behind the selection of SRYR as the subject of the study. On what grounds did the authors select this particular?

Response 1:Thank you for pointing this out. We agree with this comment.We have added relevant content in the fourth paragraph of the introduction to achieve this.

Comments 2: In the text, when referencing Figure 1, it is essential to provide a clear and concise explanation of the various colored areas depicted on the map. What do these symbols represent?

Response 2:Agree.In response to the reviewer's comments, we have included a more detailed description in the figure notes.

Comments 3: In Table 1, the column headings should be written in uppercase.

Response 3:Agree.We have meticulously revised the issues that have arisen in the text, in addition to revising and proofreading the entire text, with the revisions highlighted in red.

Comments 4: The first sentence of paragraph 2.2 requires further clarification. Please provide justification for the selection of a time step of five years. A rationale must be provided.

Response 4:Agree.Considering that due to the large amount of remote sensing data for the last 30 years used in this paper, after referring to the relevant literature, we have used 5 years of data as a reference time threshold when sorting out the data, which can better reflect the degree of change in land use. We have added explanations about this part in the text.

Comments 5: The construction of Table 2 is such that the relationship between the various elements is not immediately apparent. It is recommended that the item in question be removed from the article and that the text be incorporated into the body of paragraph 2.2.

Response 5:Agree.Changes have been made as suggested by the reviewers.

Comments 6: It would be preferable to use the term 'Equation' in place of 'Formula'.

Response 6:Agree.We have replaced 'Equation' with 'Formula'.

Comments 7: Tables 3 and 4 require elucidation and a conclusion. What is the intended meaning for the reader upon examination of these tables?

Response 7:Agree.We have provided additional notes to the text in order to increase readability for the reader.

Comments 8: It would be beneficial to ascertain whether it is imperative to include the same reference to the program in the captions to the figures. I believe that a single initial mention is sufficient.

Response 8:Agree.We have trimmed the titles of some of the charts to ensure better readability.

Comments 9 :It would be beneficial to provide a more detailed explanation of the social factors presented in conclusion 5.

Response 9:Agree.We have made content additions and improvements.

Reviewer 4 Report

Comments and Suggestions for Authors

The article addresses the well-known problem of ecosystem imbalance in China, due to the lack of sustainable development, agriculture and industry. Having included the answers to the following questions in the text, I believe that the article is suitable for publication:

-How do the authors of the study assess rationalised land use in the SRYR? -How can the improvement of the quality of the ecological environment be measured measurably? Have attempts been made to assess the species changes of flora in fauna?

-What are the forecasts for the next decades?

-How has the AECC trend for arable land and built-up areas changed, especially after 2005, and do you have any results from the last 20 years (i.e. after 2005).

Author Response

Comments 1: How do the authors of the study assess rationalised land use in the SRYR? -How can the improvement of the quality of the ecological environment be measured measurably? Have attempts been made to assess the species changes of flora in fauna?

Response 1:Thank you for pointing this out. We agree with this comment.We calculated the demand for land from human activities through the ecological footprint method and compared it with the actual carrying capacity of the land. We analysed changes in land use types, such as changes in the proportions of forests, grasslands, arable land and construction land, mainly through satellite imagery, on the basis of which we combined spatial data and statistical analyses to assess the reasonableness of the land use and the improvement of the quality of the ecological environment. In this study, we assessed whether the ecological environment quality of the Yellow River source area has been improved by the change of land use area, i.e., increase or decrease, over a 30-year period. We focused on analysing the change of ecological carrying capacity in this study, and we have not assessed the plant and animal communities for the time being.

Comments 2:What are the forecasts for the next decades?

Response 2:Thank you for pointing this out. We agree with this comment.The result of this study is that the ecological environment of the source area of the Yellow River has been getting better and better during the past 30 years, and the ecological carrying capacity of the source area of the Yellow River as well as the counties within the source area has been gradually increasing to the trend. In addition, our country pays more and more attention to the ecological value and importance of the source area of the Yellow River, and has enacted a series of laws and regulations to protect the ecological environment of the source area of the Yellow River. We have reason to believe that the ecological environment of the source area of the Yellow River will become better and better in the next few decades, and that the ecological carrying capacity will be gradually restored to the pre-destructive stage, or even exceeded.

Comments 3:How has the AECC trend for arable land and built-up areas changed, especially after 2005, and do you have any results from the last 20 years (i.e. after 2005).

Response 3:Thank you for pointing this out. We agree with this comment.Our study found that the absolute ecological carrying capacity of arable land and construction land has changed relatively little over the past 30 years. In addition, when we processed the data, we retained two decimals, which may have caused some bias in the results of the study. In fact, this part of the data, when retaining 4-5 as decimals, is able to show small changes, but the difference in changes is very small. During the past 20 years, the absolute ecological carrying capacity of arable land and construction land has fluctuated and increased in overall changes.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors iterated on the paper, generally improving all aspects of it. They have been able to follow the suggestions across the board, while acknowledging some limitations of the current research structure. In any case, the research is coherent, valid and of interest, so for me the paper now represents more sound research worthy of publication.