Research on the Evolution Characteristics and Dynamic Simulation of Habitat Quality in the Southwest Mountainous Urban Agglomeration from 1990 to 2030

Round 1

Reviewer 1 Report

1. What is the scientific problem of the passage?

2. There is still improving space in the review part of the paper. It is suggested to further sort out the logic and add the latest literature.

• 3. It is suggested to further enhance the research value and significance.

•  
• 4. What is the logic behind the need to discuss the spatiotemporal evolution of land use impacts on habitat quality? add a discussion section.
•  
• 5. A section should be added at the end of the paper to provide detailed countermeasures to improve the overall habitat quality from the perspective of land use change.

English language is OK.

Author Response

Dear Reviewer,

Thank you very much for reviewing our paper and providing valuable comments and suggestions. We sincerely appreciate your recognition and support for our work, and we have carefully considered each of your suggestions. Here is our specific response to your comments and suggestions:

Reviewer Comment 1（What is the scientific problem of the passage?）:

We have taken note of your concern regarding the scientific questions in the paper. Based on your suggestion, we have added a discussion on the limitations of previous studies and clarified the core research questions and innovations of our study (Page 3, lines 131-146).

“The above research on habitat quality in mountainous cities has certain limitations. The main reason is that the use of historical land use data results in a temporal and spatial lag in studying the evolution patterns and driving factors of regional habitat quality, which cannot capture the current and future trends of habitat quality changes in mountainous regions. Therefore, it is necessary to combine land use simulation research to predict the habitat quality of future mountainous urban ecosystems. However, there are still some issues in existing regional habitat quality simulation research. In current land use simulation studies, the simulation region is often treated as a homogeneous entity, overlooking the heterogeneity of spatial units within the simulation region. The land conversion rules based on a single scenario also face the challenge of inapplicability to large-scale regional simulation and prediction, as they fail to comprehensively reflect the future land use changes in the region. Additionally, most simulation studies neglect the policy effects of local government regulations that restrict, incentivize, and guide land use behaviors, especially regarding regional planning, construction, and ecological conservation policies. Ignoring the driving effects of policies does not align with the actual circumstances of regional development.”

 

Reviewer Comment 2（There is still improving space in the review part of the paper. It is suggested to further sort out the logic and add the latest literature.）:

Regarding your comment on the review part of the paper, we have re-evaluated and adjusted the structure of the paper. We have carefully considered your suggestion regarding the addition of the latest literature and have incorporated and replaced newer references in the literature review to align our research with the most recent developments in the field.

Replaced and added references:

1. Koellner, Thomas, et al. "Guidance for assessing interregional ecosystem service flows. Ecological Indicators, 2019,105: 92-106.
2. Zhou, Fang-Cheng, et al. An improved model for evaluating ecosystem service values using land use/cover and vegetation parameters.Journal of Meteorological Research, 2021, 35.1: 148-156.
3. XU, Li-ting, et al. Impacts of land-use change on habitat quality during 1985–2015 in the Taihu Lake Basin. Sustainability, 2019,11.13:3513
4. REN, Yanjiao, et al. Spatially explicit simulation of land use/land cover changes: Current coverage and future prospects. Earth-Science Reviews, 2019,190:398-415
5. WAN, Hui, Scott R. Stephenson, and Shijin Qu. Modeling spatially non-stationary land use/cover change in the lower Connecticut River Basin by combining geographically weighted logistic regression and the CA-Markov model. International Journal of Geographical Information Science, 2019,33.7:1313-1334
6. FAN, Xin, et al. The spatial and temporal evolution and drivers of habitat quality in the Hung River Valley. Land, 2021,10.12:1369
7. HE, Bing, et al. Assessment of river basin habitat quality and its relationship with disturbance factors: A case study of the Tarim River Basin in Northwest China. Journal of Arid Land, 2022,14.2:167-185
8. GONG, Jie, et al. Integration of InVEST-habitat quality model with landscape pattern indexes to assess mountain plant biodiversity change: A case study of Bailongjiang watershed in Gansu Province.  Journal of Geographical Sciences, 2019,19:1193-1210
9. BROWN, Greg. The relationship between social values for ecosystem services and global land cover: an empirical analysis. Ecosystem Services, 2013,5:58-68
10. Savard, Jean-Pierre L., Philippe Clergeau, and Gwenaelle Mennechez. Biodiversity concepts and urban ecosystems. Landscape and urban planning, 2000,48.3-4:131-142.
11. Yang, Xiaojun, and C. P. Lo. Modelling urban growth and landscape changes in the Atlanta metropolitan area. International journal of geographical information science, 2003,17.5:463-488.
12. Yuanyuan Yang. Evolution of habitat quality and association with land-use changes in mountainous areas: A case study of the Taihang Mountains in Hebei Province, China. Ecological Indicators. 2021, 129, 107967.
13. Dincer, Ibrahim. Renewable energy and sustainable development: a crucial review. Renewable and sustainable energy reviews, 2000,4.2:157-175.
14. Wang, Rongyao, et al. Coupling PLUS–InVEST Model for Ecosystem Service Research in Yunnan Province, China. Sustainability, 2022,15.1:271.
15. Zeleke, Gete, and Hans Hurni. Implications of land use and land cover dynamics for mountain resource degradation in the Northwestern Ethiopian highlands. Mountain research and development, 2001,21.1:184-191.

 

Reviewer Comment 3（It is suggested to further enhance the research value and significance.）:

We greatly appreciate your suggestion regarding the research value and significance of our paper. In response to your advice, we have revised the section on the research significance and value to more explicitly express the importance of our study and ensure that readers fully understand its significance. We have revised this section to highlight the value of our research (Page 4, lines 164-169).

“This study contributes to the further enrichment of ecological conservation theories in mountainous areas, supports the layout and optimization of regional ecological con-servation areas, as well as the formulation of policies related to ecological compensation and regulation measures. It provides scientific guidance for the high-quality develop-ment of mountainous regions in the upper Yangtze River Basin.”

 

Reviewer Comment 4（What is the logic behind the need to discuss the spatiotemporal evolution of land use impacts on habitat quality? add a discussion section.）:

Thank you for your suggestion to include a discussion on the mechanisms of land use impacts on habitat quality in the discussion section. Following your advice, we have added a separate subsection and elaborated on the drivers of land use change and how it affects habitat quality. (Pages 19-20, lines 668-717).

“Chongqing Urban Agglomeration is a typical mountainous city characterized by its topographical features, including high mountains, canyons, lakes, and diverse eco-systems, which contribute to its complex landscape and diverse habitats. The im-pact of land use changes on the ecological systems and habitat quality in the region is a crucial and complex issue. Driven by national strategies, the Chongqing Urban Ag-glomeration plays a vital role in the economic development of the Chengdu-Chongqing dual-city region. To promote local economic growth and industrialization, as well as meet the demands of productive economic activities, there is a need to expand the scale of industrial and commercial land use. Consequently, new manufacturing industrial clusters and supporting infrastructure, such as the designated Western Science City at the border of Shapingba District and Bishan District, and the planned High-speed Rail New Area, are being developed. This leads to the transformation of natural land types within these areas into industrial parks and commercial centers. The planning and construction of these industrial clusters drive regional economic development, which, in turn, results in population growth and urbanization. The rapid increase in population requires the consumption of a significant amount of land for residential, commercial, and infrastructure development to accommodate the growing population. As a result, a large amount of natural land is converted into built-up areas, which is one of the main driving forces behind land use changes in the Chongqing Urban Agglomeration. Fur-thermore, to support the industrial parks and residential areas, the development of re-gional mineral resources, energy resources, and timber resources is necessary. This further transforms the original natural land into mining areas and various types of green spaces. The intense human activities in land transformation can disrupt the natural habitats within the region, causing the fragmentation of once-intact and continuous large-scale natural habitats, especially in the complex terrain of mountainous urban areas. Due to the limitations imposed by the topography, urban development tends to occur in plains and gently sloping areas. On one hand, the mountain corridors impede urban expansion, and on the other hand, the sprawling of cities on flat areas disconnects ecological regions, affecting the migration and dispersal of species within different ecological systems, reducing habitat connectivity, and thus impacting the re-production and survival of species. Activities such as mining and logging, which are involved in the exploitation of natural resources, tend to destroy the natural landscape and cause pollution to air, water sources, and soil. The accumulation of pollutants can lead to soil erosion and further aggravate ecological degradation. Therefore, the cumulative effects of resource exploitation can cause long-term ecological damage to the ecosystems within the region, not only affecting the sustainable development of natural resource extraction but also impacting the overall health and resilience of the system. Moreover, excessive production activities in industrial-agricultural areas within urban regions can result in the accumulation of pollutants, increase the pressure on re-source utilization, and cause environmental damage. The land use changes dramatically alter the living environment and resource availability for local species, which in turn affect their adaptability within the region. While some species may benefit from human-induced land transformations, others may struggle to adapt to the rapidly changing environment, leading to a decrease in species abundance and diversity, or even endangerment.

In summary, land use change has a direct impact on the evolution of habitat qual-ity in mountainous cities. To achieve the coordinated development of socio-economy and ecological systems, it is essential to fully consider the significance of ecological systems and habitat quality for regional sustainable development. From the perspective of land use planning, it is necessary to allocate land use types reasonably, strengthen land protection and restoration, and promote sustainable land use practices.”

 

Reviewer Comment 5（A section should be added at the end of the paper to provide detailed countermeasures to improve the overall habitat quality from the perspective of land use change.）:

We would like to express our sincere gratitude for your suggestion on improving and restoring habitat quality in the conclusion section. In response, we have added a subsection after the conclusion, where we provide our recommendations from the perspectives of policy-making, land use planning, and awareness education for ecological conservation. (Pages 22, lines 790-807).

“Based on the conclusions of this study, the following recommendations are pro-posed to protect and improve the habitat quality in the research area: (1) Prioritize the establishment of ecological protected areas in regions with poor habitat quality. Strengthen environmental monitoring and ecological protection efforts in these areas to prevent further degradation of the ecological environment. (2) Control land use from an urban planning perspective. Promote the intensive use of land resources while considering the preservation of urban green spaces and natural landscapes in the planning process. These areas can provide ecosystem services and support the overall health of the regional ecosystem, balancing urbanization and ecological conservation. (3) Utilize technologies such as big data analysis, unmanned aerial vehicles (UAVs), and monitor-ing sensors to establish a regional ecological system health monitoring network. Collect and analyze monitoring data to assess the health status of the ecosystem in real time, providing scientific evidence to support decision-making and policy formulation by relevant departments. (4) Strengthen public awareness and education on ecological conservation. Guide the public to raise environmental awareness and foster a culture of protecting the ecological environment. These measures can effectively protect and im-prove the ecological environment of the Chongqing metropolitan area, achieving a harmonious development between the environment and the economy.”

 

In addition to addressing your specific comments and suggestions, we have thoroughly revised and modified the entire paper to enhance its structure, language, and clarity of expression. We believe these improvements will further enhance the quality and readability of our paper.

Once again, we sincerely thank you for your diligent work and valuable insights during the review process. We consider your suggestions as valuable guidance and will make every effort to improve and refine our paper. If you have any further comments or suggestions, please feel free to let us know, and we will be more than happy to further improve.

Thank you for your time and expertise!

 

Best regards,

Taquan Ma

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

This study evaluated spatiotemporal variations of habitat quality in a mountainous city under the pressure of urban expansion. However, authors are supposed to further highlight what the major limitations in the literature and contributions of this study are. I suggest a major revision to improve the illustration on the part of comparisons with the literature. 

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thank you very much for reviewing our paper and providing valuable comments and suggestions. We sincerely appreciate your recognition and support for our work, and we have carefully considered each of your suggestions. Here is our specific response to your comments and suggestions:

Reviewer Comment 1 (Line 103 in Page 3: What is the reference for Yang et al.?):

Regarding the missing reference, we have supplemented the corresponding literature as suggested (Page 3, line 104).

Yang, Z.; Wang, S.; Guo, M.; Tian, J.; Zhang, Y. Spatiotemporal Differentiation of Territorial Space Development Intensity and Its Habitat Quality Response in Northeast China. Land, 2021, 10, 573.

 

Reviewer Comment 2 (Line 125 in Page 3: What is the reference for Yang?):

Regarding the missing reference, we have supplemented the corresponding literature as suggested (Page 3, line 127).

Yuanyuan Yang. Evolution of habitat quality and association with land-use changes in mountainous areas: A case study of the Taihang Mountains in Hebei Province, China. Ecological Indicators. 2021, 129, 107967.

 

Reviewer Comment 3 (Lines 120-130 in Page 3: Although authors illustrated what previous studies did here, they should explain more clearly what their limitations were or what they ignored.):

We have noticed your concern regarding the limitations of previous studies and the innovative contributions of our paper. Based on your suggestion, we have added a discussion on the limitations of previous studies and clarified the core research questions and innovations of our study (Page 3, lines 131-146).

“The above research on habitat quality in mountainous cities has certain limitations. The main reason is that the use of historical land use data results in a temporal and spatial lag in studying the evolution patterns and driving factors of regional habitat quality, which cannot capture the current and future trends of habitat quality changes in mountainous regions. Therefore, it is necessary to combine land use simulation research to predict the habitat quality of future mountainous urban ecosystems. However, there are still some issues in existing regional habitat quality simulation research. In current land use simulation studies, the simulation region is often treated as a homogeneous entity, overlooking the heterogeneity of spatial units within the simulation region. The land conversion rules based on a single scenario also face the challenge of inapplicability to large-scale regional simulation and prediction, as they fail to comprehensively reflect the future land use changes in the region. Additionally, most simulation studies neglect the policy effects of local government regulations that restrict, incentivize, and guide land use behaviors, especially regarding regional planning, construction, and ecological conservation policies. Ignoring the driving effects of policies does not align with the actual circumstances of regional development.”

 

Reviewer Comment 4 (Line 131 in Page 3: I am wondering what issues are in "Considering these issues".):

The "issues" referred to here are the limitations of previous studies (Page 3, lines 131-146).

“Please refer to the response to comment 3 for details.”

 

Reviewer Comment 5 (Figure 1: Please also include a scale bar in the left-side sub-images. Additionally, the label on the bottom left image is confused. Where are exactly Sichuan and Chongqing?):

Regarding the confusion in the image information, we have revised Figure 1 according to your suggestion. We have added a scale bar to the thumbnail images and highlighted the locations of Sichuan and Chongqing (Page 5, lines 189-192, Figure 1.).

 

Reviewer Comment 6 (Line 182 in Page 4: Please specify the five periods here.):

Thank you for your suggestion, which helped us identify an expression error in the original text. We have made the necessary correction. This study utilized land use data for seven time points in the study area, rather than five periods. (Page 5, lines 197-200).

“The land use data includes six primary categories, including cropland, forest land, grassland, water bodies, built-up land, and unused land. This study utilized land use grid data for seven time points in the Chongqing Metropolitan Area, specifically the years 1990, 1995, 2000, 2005, 2010, 2015, and 2020.”

 

Reviewer Comment 7 (Figure 4: Authors show the land use expansion from 1990 to 2020. I am wondering how about patterns in different periods.):

According to your suggestion, we have elaborated on the expansion patterns of land cover types in different periods through statistical analysis (Page 11, lines 405-418).

“We analyzed the expansion of each land type in the study area on a 10-year cycle from 1990 to 2020 to understand the variability of the expansion patterns of different land types (grassland, watershed and unused land were excluded from the discussion for the time being due to insignificant changes in expansion). 1990-2000, the study area expanded 92.02 km², 173.34 km² and 15.81 km² of cultivated, forested and built-up land respectively; 2000-2010, the study area expanded 102.91 km², 113.27 km² and 38.46 km² of cultivated, forested and built-up land respectively, From 2000 to 2010, the study area expanded 102.91 km², 113.27 km², and 38.46 km² of cropland, forest land, and construction land, respectively; from 2010 to 2020, the study area expanded 157.72 km², 127.84 km², and 70.8 km² of cropland, forest land, and construction land, respectively. In conclusion, cropland and forest land expand and flow with each other in the southeastern part of the study area and within the ecological corridor, and construction land from the initial development stage in 1990-2000, the rapid expansion stage during 2000-2010, and finally the stable growth stage in 2010-2020.”

 

Reviewer Comment 8 (Figure 5: Title is incorrect.):

Thank you for pointing out the error! We have made the necessary correction to the title of Figure 4, (originally Figure 5, “Land use simulation results of Chongqing metropolitan area in 2030”).

 

Reviewer Comment 9 ("Compared to 2020, there is significant expansion in the forest areas of southeastern Qijiang, Fuling, Nanchuan, Banan districts, as well as the mountainous areas in the north." If this sentence is for the pattern showing in Figure 5, I suggest it could be moved to where you explain Figure 5.):

Based on your suggestion, we have adjusted the relevant text to enhance the logical coherence of the paper (Page 12-13, lines 432-444).

        “Compared to 2020, there is significant expansion in the forest areas of southeast-ern Qijiang, Fuling, Nanchuan, Banan districts, as well as the mountainous areas in the north. The ecological control areas are mostly ecological corridors, indicating significant effects of the ecological control policy on ecosystem restoration. The built-up area has increased in all three types of regions, with the largest increase occurring under the construction development policy. A large amount of arable land has been convert-ed into built-up areas, resulting in a growth of 12.35% compared to 2020, representing an increase of 47.86 km². Spatially, it is mainly manifested as radial urban expansion in the central region, with areas such as Yubei, Jiangbei, Shapingba, Jiulongpo, and Dadukou districts as the main expansion areas, while other regions show scattered patches of built-up area expansion. Under the ecological control policy, the water body area has increased by 7.09 km², representing a growth of 0.69%. However, there is a slight decrease (0.04%, 0.05%) in water body area under the projections of natural growth and construction development.”

 

Reviewer Comment 10 (The number "46.86 km²" is different from the number shown in Table 5):

Thank you for pointing out the error! We have corrected it according to your suggestion (Page 12, line 438).

        “A large amount of arable land has been converted into built-up areas, resulting in a growth of 12.35% compared to 2020, representing an increase of 47.86 km².”

 

Reviewer Comment 11 (I am wondering why areas of different land cover types are so different in 2020 under three scenarios?):

According to your suggestion, we have provided an explanation for the differences in landcover areas among different scenarios from the perspective of functional aspects of spatial units. We hope to address your question (Page 13, lines 445-459).

        “Through Table 5, we can observe significant differences in the area of different land use types within spatial units under different scenarios, which are due to regional differentiated development strategies. Among them, the planning and construction spatial units are driven by policy and actively engage in urban development and socioeconomic growth. These units primarily provide a range of functions such as residential, industrial, commercial services, and transportation. In urban expansion, arable land with gentle terrain is typically used as reserve land for expansion. Therefore, construction land and arable land are the main components of the planning and construction units. The natural conservation units are designated by relevant government departments to improve the ecological environment in the region. They serve as important ecological barriers in the study area and are mainly composed of forestland and arable land. On the other hand, the natural simulation units differ from the other two types of regions. They primarily serve the function of ensuring food security with ecological regulation as a secondary objective. Therefore, these units are mainly com-posed of arable land and forestland, with a larger proportion of "agriculture-forestry" area compared to the conservation units.”

 

Reviewer Comment 12 (I am wondering what regions are shown in the x-axis.):

Based on your suggestion, we have made adjustments to Figure 5, allowing the X-axis to display the names of regional administrative units (Page 15, lines 505-507, Figure 5.).

 

Reviewer Comment 13 (Lines 446-447 in Page 14: "the overall habitat quality is categorized into three levels: Level III (0-0.2), Level II (0.2-0.4), and Level I (>0.4)". What is the reference for such a classification? I am wondering why authors do not use the classification scheme they use below (i.e., very low (0-0.2), low (0.2-0.4), medium (0.4-0.6), high (0.6-0.8), and very high-high (0.8-1)).):

Thank you for the suggestion. To increase the logical coherence of the text, we have adjusted the structure of the paper. We have introduced the classification method for habitat quality levels at the beginning of Section 3.2.1 and continued using this classification method to classify and grade habitat quality in different regions in Section 3.2.2 (Page 15, lines 508-515).

“According to the classification method mentioned above, the overall habitat qual-ity is divided into three levels: Level I (0-0.2), Level II (0.2-0.4), and Level III (>0.4). Over the course of 30 years, only Nanchuan District and Yuzhong District fall within the Level III and Level I range of habitat quality. The regions with habitat quality ranging between Level II and Level I constitute the main part of the study area. Over a span of 40 years, the regions where the overall habitat quality declined from Level II to Level I include Beibei District, Shapingba District, Bishan District, Tongliang District, Dazu District, Yubei District, Jiangbei District, Nan'an District, and Dadukou District.”

 

Reviewer Comment 14 (I suggest authors can delete Figure 7 because Table 6 and Figure 8 may show the changes in habitat quality.):

Based on your suggestion, we have removed Figure 7 and made corresponding adjustments to the structure of the paper.

 

Reviewer Comment 15 (Lines 542-543 in Page 17: "Level 1 degradation, Level 2 degradation, Level 3 degradation, and Level 4 degradation". Are there any references to this classification? What do they represent?):

 Based on your suggestion, we realized that the explanation of habitat degradation levels in the text was not sufficient. Therefore, we have provided a detailed description of this classification method in the paper. This classification is based on the classification method for habitat quality levels mentioned earlier in the text and defines degradation levels based on the intensity of habitat quality decline (Page 17, lines 581-593).

        “According to the classification of regional habitat quality mentioned earlier, the phenomenon of decreasing habitat quality is referred to as habitat degradation. Based on the intensity of habitat quality decline, habitat degradation can be categorized into four levels: Level 1 degradation (very high to high, high to moderate, moderate to low, low to very low), Level 2 degradation (very high to moderate, high to low, moderate to very low), Level 3 degradation (very high to low, high to very low), and Level 4 degradation (very high to very low). By utilizing the raster calculator and reclassification tools in ArcGIS, we obtained the terrain position index and habitat degradation distribution index for the study area. As shown in Figure 8, the habitat degradation values across different terrain position gradients in the Chongqing metropolitan area varied from 1990 to 2030. The overall trend can be divided into three stages: 1990-2005, 2005-2030, and beyond 2030. Each stage exhibits similar graphical trends and the dominant role of habitat degradation on each terrain position gradient.”

 

Reviewer Comment 16 (Line 191 in Page 5: Section number should be 2.2.2.):

We have made the necessary correction based on your suggestion (Page 5, line 208).

 

Reviewer Comment 17 (Line 435 in Page 13: Section number should be 3.2.1.):

We have made the necessary correction based on your suggestion (Page 14, lines 477-478).

 

Reviewer Comment 18 (Line 466 in Page 14: Section number should be 3.2.2):

We have made the necessary correction based on your suggestion (Page 14, lines 498-499).

 

Reviewer Comment 19 (Line 469 in Page 14: "(Figure 5)" is not correct here.):

We have made the necessary correction based on your suggestion (Page 12, line 431).

 

Reviewer Comment 20 (Line 500 in Page 16: Section number should be 3.2.3.):

We have made the necessary correction based on your suggestion (Page 15, lines 528-529).

 

Reviewer Comment 21 (Line 577 in Page 18: I suggest that "From Table 7" can be deleted.):

We have made the necessary correction based on your suggestion (Page 18, line 621).

 

In addition to addressing your specific comments and suggestions, we have thoroughly revised and modified the entire paper to improve its structure, language, and clarity of expression. We believe these improvements will further enhance the quality and readability of our paper.

 

Once again, we sincerely appreciate your hard work and valuable feedback during the review process. We consider your suggestions as valuable guidance and will make every effort to improve and refine our paper. If you have any further comments or suggestions, please feel free to let us know. We would be more than happy to further enhance our work.

 

Thank you for your time and expertise.

 

Best regards,

Taquan Ma

Author Response File: Author Response.docx

Reviewer 3 Report

Respected Editor

This manuscript produces evolution characteristics and dynamic simulation of habitat quality in the southwest mountainous urban agglomeration from 1990 to 2030. In general, the analyses are robust and some aspects of the manuscript are well written and I enjoyed reading about the findings. I have some comments regarding the manuscript. The manuscript would benefit from a more detailed discussion of the shifts in habitat quality in relation to existing or proposed future mountain areas.

The introduction needs to be revised according to the topic and should improve aims and objectives.

In the results, the section should be a statistical analysis of significant changes in habitat under different time periods.

The discussion is general and should be improved in the context of results.

The authors highlighted the limitations of the study I suggest must provide future perspectives and impacts for this study.

Author Response

Dear Reviewer,

Thank you very much for reviewing our paper and providing valuable comments and suggestions. We greatly appreciate your recognition and support for our work, and we have carefully considered each of your suggestions. Here is our specific response to your comments and suggestions:

 

Reviewer Comment 1(The manuscript would benefit from a more detailed discussion of the shifts in habitat quality in relation to existing or proposed future mountain areas.):

According to your suggestion, we have added a discussion in Section 4.1 based on our simulation results of future habitat quality in the study area, aiming to improve the readability of the manuscript. (Page 19, lines 646-667)

        “According to the findings of this study, we have observed a continuous decrease in overall habitat quality in the study area until 2030. The degradation of habitat quality is gradually spreading towards higher elevation and steeper slope areas within the study area, which is a concerning signal for a typical mountainous urban region like this. Mountainous ecosystems are inherently fragile, and the loss of regional biodiversity not only affects the balance of natural ecosystems but also impacts the ecosystem services essential for human survival, leading to a reduction in accessible natural re-sources. Furthermore, the decline in habitat quality may exacerbate the extent of environmental pollution, with air and water pollution potentially affecting human health systems. The deterioration of environmental quality, coupled with issues such as noise pollution, traffic congestion, and declining air quality resulting from urbanization, adversely affect the living quality of people, thereby exerting a negative impact on their mental well-being and weakening social cohesion. At the same time, Due to the com-plex topography of mountainous cities, the destruction of ecosystems and the reduction in habitat quality can increase the frequency of natural disasters such as landslides, de-bris flows, and earthquakes. Furthermore, urbanization leads to an increase in population density and the density of buildings in the region, which exacerbates the risk of natural disasters in the study area.

Therefore, protecting and improving habitat quality is crucial for maintaining human well-being. Quantitative assessment and prediction of habitat quality in the Chongqing metropolitan area are of great significance for optimizing land use planning and ecological governance policies, and promoting the sustainable development of mountainous urban areas.”

 

Reviewer Comment 2(The introduction needs to be revised according to the topic and should improve aims and objectives.):

Thank you very much for your comments on the introduction section. Based on your feedback, we have made the following revisions to the introduction: 1. Added a description of the limitations of previous studies. 2. Presented the research questions and innovation points of our study. 3. Rewritten the objectives and significance of the study to highlight its importance and value. (Page 3, lines 131-146; Page 4, lines 164-169)

        “This study contributes to the further enrichment of ecological conservation theories in mountainous areas, supports the layout and optimization of regional ecological con-servation areas, as well as the formulation of policies related to ecological compensation and regulation measures. It provides scientific guidance for the high-quality develop-ment of mountainous regions in the upper Yangtze River Basin.”

 

Reviewer Comment 3(In the results, the section should be a statistical analysis of significant changes in habitat under different time periods.):

We sincerely appreciate your comments on the results section. Based on your feedback, in Section 3.2.3, we have analyzed the changes in habitat quality hotspots and cold-spots in the study area from a spatiotemporal perspective using statistical analysis. We have also added Figure 6 to provide readers with necessary information about the changes in hotspot and cold-spot areas from 1990 to 2030. Furthermore, we have made corresponding adjustments to improve the logical coherence of this section. (Pages 15, 16, 17, lines 530-578)

“As shown in Figure 6 and Figure 7, From 1990 to 2030, the hotspots and cold-spots of habitat quality exhibit significant spatiotemporal variations. In terms of time, although the hotspots generally show an increasing trend in area, the fluctuations are relatively small. On the other hand, the cold-spots, except for the core cold-spot area, experience a notable decrease in area for both the sub-core cold-spot and the edge cold-spot regions, with larger fluctuations. Spatially, the hotspots are mainly concentrated in the southeastern part of the study area, while the cold-spots are predominantly distributed in the central region. Over the 40-year period, the hotspots demonstrate relative spatial stability, while the cold-spots exhibit a significant expansion phenomenon, radiating extensively from the core region in the center towards the western part of the study area.

The area changes of cold and hotspots of habitat quality in the study area of the Chongqing metropolitan area from 1990 to 2030 can be summarized as follows: The hotspots, representing areas of high habitat quality, showed an overall increasing trend in their area, although the magnitude of change was relatively small. The core hotspots, sub-core hotspots, and peripheral hotspots had an area range of 3952.2 km² to 4291.7 km², 493 km² to 604.1 km², and 297.4 km² to 414.5 km², respectively. During the 40-year period, they expanded by 339.5 km², 110.2 km², and 117.1 km², respectively, with relatively stable fluctuations in between. The area changes of cold-spots in the study area exhibited significant differences and showed stage-specific patterns. The core cold-spots experienced an "increase-decline-increase" trend. From 1990 to 2000, their area increased from 2084 km² to 7132 km², followed by a decline to 3116 km² from 2000 to 2005, and ultimately rose to 8944 km² by 2030. The sub-core cold-spots had the largest initial area of 14484 km² and showed a generally declining trend over the entire period, with a slight rebound from 2000 to 2005 and a subsequent accelerated decline. Their area decreased from 12908 km² to 3608 km² in the 20-year period. The peripheral cold-spots exhibited an overall "decline-increase" pattern. From 1990 to 2000, the area decreased from 4256 km² to 2344 km², followed by a continuous increase to 8944 km² by 2030.Areas without significant changes showed an overall increasing trend in their area, with a small decrease observed from 1995 to 2000, but it did not affect the overall trend. During the 40-year period, their area ranged from 9460.4 km² to 14493.6 km², increasing by 5033.2 km².

Over the course of 40 years, the hotspots in the southeastern part of the study area showed no significant changes and were mainly distributed along the southwestern periphery, as well as small-scale clusters in the mountain corridor region in the north-eastern part of the study area. The changes in cold-spot areas can be divided into two stages. The first stage, from 1990 to 2005, witnessed the gradual expansion of cold-spot areas in the central region of the study area, but with a relatively stable growth rate. Significant changes occurred in the cold-spot areas of Tongnan County, Hechuan District, and Guangan City in the northern part of the study area during this stage. These cold-spots rapidly expanded between 1995 and 2000, followed by a rapid decline be-tween 2000 and 2005. From 2010 to 2030, the cold-spot areas of the entire study area entered a phase of rapid expansion. The core cold-spot area in the central region expanded in both the east and west directions, with an increasing expansion rate. Ultimately, by 2030, a large-scale aggregation of cold-spot areas formed in the central and western parts of the study area.”

 

Reviewer Comment 4(The discussion is general and should be improved in the context of results.):

Thank you very much for your suggestions regarding the discussion section. Following your advice, in addition to the discussion and analysis based on the simulated results of future habitat quality in the study area, we have added a dedicated discussion section, elaborating on the drivers of land use change and how they affect habitat quality. (Pages 19-20, lines 668-717)

        “Chongqing Urban Agglomeration is a typical mountainous city characterized by its topographical features, including high mountains, canyons, lakes, and diverse eco-systems, which contribute to its complex landscape and diverse habitats. The im-pact of land use changes on the ecological systems and habitat quality in the region is a crucial and complex issue. Driven by national strategies, the Chongqing Urban Ag-glomeration plays a vital role in the economic development of the Chengdu-Chongqing dual-city region. To promote local economic growth and industrialization, as well as meet the demands of productive economic activities, there is a need to expand the scale of industrial and commercial land use. Consequently, new manufacturing industrial clusters and supporting infrastructure, such as the designated Western Science City at the border of Shapingba District and Bishan District, and the planned High-speed Rail New Area, are being developed. This leads to the transformation of natural land types within these areas into industrial parks and commercial centers. The planning and construction of these industrial clusters drive regional economic development, which, in turn, results in population growth and urbanization. The rapid increase in population requires the consumption of a significant amount of land for residential, commercial, and infrastructure development to accommodate the growing population. As a result, a large amount of natural land is converted into built-up areas, which is one of the main driving forces behind land use changes in the Chongqing Urban Agglomeration. Furthermore, to support the industrial parks and residential areas, the development of regional mineral resources, energy resources, and timber resources is necessary. This further transforms the original natural land into mining areas and various types of green spaces. The intense human activities in land transformation can disrupt the natural habitats within the region, causing the fragmentation of once-intact and continuous large-scale natural habitats, especially in the complex terrain of mountainous urban areas. Due to the limitations imposed by the topography, urban development tends to occur in plains and gently sloping areas. On one hand, the mountain corridors impede urban expansion, and on the other hand, the sprawling of cities on flat areas disconnects ecological regions, affecting the migration and dispersal of species within different ecological systems, reducing habitat connectivity, and thus impacting the re-production and survival of species.  Activities such as mining and logging, which are involved in the exploitation of natural resources, tend to destroy the natural landscape and cause pollution to air, water sources, and soil. The accumulation of pollutants can lead to soil erosion and further aggravate ecological degradation. Therefore, the cumulative effects of resource exploitation can cause long-term ecological damage to the ecosystems within the region, not only affecting the sustainable development of natural resource extraction but also impacting the overall health and resilience of the system. Moreover, excessive production activities in industrial-agricultural areas within urban regions can result in the accumulation of pollutants, increase the pressure on re-source utilization, and cause environmental damage. The land use changes dramatically alter the living environment and resource availability for local species, which in turn affect their adaptability within the region. While some species may benefit from human-induced land transformations, others may struggle to adapt to the rapidly changing environment, leading to a decrease in species abundance and diversity, or even endangerment.

In summary, land use change has a direct impact on the evolution of habitat qual-ity in mountainous cities. To achieve the coordinated development of socio-economy and ecological systems, it is essential to fully consider the significance of ecological systems and habitat quality for regional sustainable development. From the perspective of land use planning, it is necessary to allocate land use types reasonably, strengthen land protection and restoration, and promote sustainable land use practices.”

 

Reviewer Comment 5(The authors highlighted the limitations of the study I suggest must provide future perspectives and impacts for this study.):

Thank you for pointing out the need for future perspectives in our study. Based on your suggestion, we have supplemented and adjusted Section 4.3, reorganized the text to improve its readability. After describing the limitations of the study, we have added some prospects for future research in terms of reducing the limitations of the research methods and enhancing the research depth. (Pages 20-21, lines 719-750)

“This study simulated the land use in the Chongqing metropolitan area in 2030 using the coupled PLUS-InVEST model, driven by policy background, and explored the evolution trajectory of habitat quality in the study area from 1990 to 2030. However, the study has some limitations [60]. The InVEST model, widely used and developed by Stanford University, is employed in this research for evaluating ecosystem services and trade-offs. Although it aids in assessing the impacts of land use decisions on ecosystem services, it has certain limitations that affect its application. These limitations include: (1) reliance on high-quality base data for accurate outputs, (2) limited spatial resolution that may overlook important spatial characteristics, (3) time-scale dependency of habitat quality results, which may vary in reality, and (4) the importance of validating the authenticity of model calculations, a significant issue in ecological modeling. The PLUS (Planning for Land Use Systems) model, extensively used for land use planning and management decision support, also has limitations similar to the InVEST model regarding data quality, spatial scale, and temporal scale. Moreover, the PLUS model neglects the influence of human factors when simulating land use changes, which can impact the accuracy of simulated results. Therefore, we hope to address the following points in future research to improve the relevant directions: (1) further expanding the study area to encompass more geographical regions and ecosystem types for comprehensive data results and discussions, while introducing multiple regions for comparison to better understand the relationship between land use and ecosystems, (2) establishing small-scale monitoring stations to obtain actual observational data on regional ecology, comparing model outputs with real observation data to assess the fit between model results and actual data, and further adjusting model parameters based on the evaluation results, (3) considering the influence of social changes and economic development on land use in future land use simulation studies, constructing relevant indicator systems to assess regional development trends, and providing more accurate support for model outputs, (4) Further delving into the mechanisms by which land use affects habitat quality, encompassing the varying impacts of different land use types and the interplay of influencing factors, will enable a comprehensive understanding. By conducting a thorough analysis of these mechanisms, it will be possible to formulate more precise policy recommendations and implement effective management measures for mountainous urban areas, facilitating the achievement of sustainable development goals for the ecological environment.”

 

In addition to addressing your specific comments and suggestions, we have comprehensively revised and edited the entire paper to enhance its structure, language, and clarity of expression. We believe that these improvements will further enhance the quality and readability of our paper.

Once again, we sincerely appreciate your hard work and valuable insights during the review process. We consider your suggestions as valuable guidance and will make every effort to improve and refine our paper. If you have any further comments or suggestions, please feel free to let us know, and we would be more than happy to make further improvements.

Thank you very much for your time and professional expertise!

 

Best regards,

Taquan Ma

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The quality of the paper has been well improved, and it is suggested that the author further optimize the conclusion.

good.

Author Response

Dear Reviewer,

Thank you very much for reviewing our paper and providing valuable comments and suggestions. We sincerely appreciate your recognition and support for our work, and we have carefully considered each of your suggestions. Here is our specific response to your comments and suggestions:

Reviewer Comment 1（The quality of the paper has been well improved, and it is suggested that the author further optimize the conclusion.）:

Thank you for your suggestions regarding the conclusion of the paper. We have made adjustments and optimizations to the conclusion based on your feedback, aiming to enhance the readability of the text.（page 20-21,lines 753-781）

（1）During the period from 1990 to 2030, significant changes were observed in the land use structure of the study area. From 1990 to 2020, there was an expansion in the area of built-up land, grassland, and water bodies, while the area of cultivated land, forestland, and unused land gradually decreased. The land use simulation results for 2030 indicate that, under the influence of urban planning and ecological control policies, there is an increase in the area of forestland, built-up land, and water bodies, while there is a decrease in the area of cultivated land, grassland, and unused land.

（2）During the period from 1990 to 2030, the habitat quality in the study area exhibited significant spatial heterogeneity, with an overall declining trend across different regions, gradually forming a spatial pattern of "lower in the central-western part and higher in the southeastern part". The low-value habitat areas were primarily concentrated in the middle of the metropolitan area and expanded outward, radiating towards the western part of the study area, showing more pronounced changes in these areas. The high-value habitat areas were mainly concentrated in the southeastern part of the study area, including Nanchuan District, Qijiang District, Jiangjin District, and Fuling District, as well as mountain corridor regions like Huaying Mountain, where the changes in these areas were relatively stable.

（3）The spatial distribution of habitat quality in the study area exhibits a significant topographic gradient effect. The dominant position of habitat degradation gradually shifted from regions with gentle topographic gradients to those with steeper gradients. However, with the rapid socio-economic development in the study area, the degradation of higher-level habitat quality areas expanded towards higher-altitude and steeper slope regions within the study area.

（4）The expansion of built-up land is the primary cause of habitat degradation in the study area. Between 1990 and 2030, under the context of urban planning and economic development in the study area, built-up land has expanded to varying degrees at different stages, encroaching upon cultivated land and ecological land. This has resulted in a sustained decline in overall habitat quality, thereby increasing the risk of ecological and social issues.

 

Once again, we sincerely thank you for your diligent work and valuable insights during the review process. We consider your suggestions as valuable guidance and will make every effort to improve and refine our paper. If you have any further comments or suggestions, please feel free to let us know, and we will be more than happy to further improve.

Thank you for your time and expertise!

Best regards,

Taquan Ma

Reviewer 2 Report

The authors made a significant improvement in the manuscript. There are several further suggestions.

1. Line 136: Please provide references for “regional habitat quality simulation research” for each point the authors illustrated (i.e., treated as a homogeneous entity, neglect the policy effects of local government regulations) 

2. Lines 164-169: I suggest that they can be moved to Discussion.

3. Lines 408: Please change “1990-2000” to “From 1990 to 2000”.

4. Line 410: Please change “2000-2010” to “From 2000 to 2010”.

5. Lines 410-412: They are the same, please check carefully.

There are minor errors in writing, please double check.

Author Response

Dear Reviewer,

Thank you very much for reviewing our paper and providing valuable comments and suggestions. We sincerely appreciate your recognition and support for our work, and we have carefully considered each of your suggestions. Here is our specific response to your comments and suggestions:

Reviewer Comment 1（ Line 136: Please provide references for “regional habitat quality simulation research” for each point the authors illustrated. ）:

Regarding your comment on the review part of the paper, we have re-evaluated and adjusted the structure of the paper. We have carefully considered your suggestion regarding the addition of the latest literature and have incorporated and replaced newer references in the literature review to align our research with the most recent developments in the field.(page 3,lines 139)

Added references:

1. Ren Yinming, Liu Xiaoping, Xu Xiaocong et al. Multi-scenario land use change simulation in Beijing-Tianjin-Hebei based on FLUS-InVEST model and its impact on ecosystem service function[J]. Journal of Ecology,2023,43(11):4473-4487.
2. Chen Liting, Cai Haisheng, Zhang Ting et al. Multi-scenario simulation analysis of land use in Raohe River Basin based on Markov-FLUS model[J]. Journal of Ecology,2022,42(10):3947-3958.
3. Li L, Huang X, Yang H. Scenario-based urban growth simulation by incorporating ecological-agricultural-urban suitability into a future land use simulation model[J]. Cities, 2023, 137: 104334.

Reviewer Comment 2（ Lines 164-169: I suggest that they can be moved to Discussion.）:

Thank you for your suggestion. We have moved the mentioned portion of the text to the discussion section based on your feedback.（page 19, lines 656-661）

Therefore, protecting and improving habitat quality is crucial for maintaining human well-being. This study contributes to the further enrichment of ecological conservation theories in mountainous areas, supports the layout and optimization of regional ecological conservation areas, as well as the formulation of policies related to ecological compensation and regulation measures. It provides scientific guidance for the high-quality development of mountainous regions in the upper Yangtze River Basin.

Reviewer Comment 3（Lines 408: Please change “1990-2000” to “From 1990 to 2000”）:

Thank you for your suggestion. We have made the necessary corrections to the text based on your feedback.（page 11, lines 403）

From 1990 to 2000, the study area expanded 92.02 km², 173.34 km² and 15.81 km² of cultivated, forested and built-up land respectively

Reviewer Comment 4（Line 410: Please change “2000-2010” to “From 2000 to 2010”）:

Thank you for your suggestion. We have made the necessary corrections to the text based on your feedback.（page 11, lines 405）

From 2000 to 2010, the study area expanded 102.91 km², 113.27 km², and 38.46 km² of cropland, forest land, and construction land, respectively

Reviewer Comment 5（Lines 410-412: They are the same, please check carefully）:

Thank you for your suggestion. We have removed the duplicated parts in the text and reviewed the remaining content.

Once again, we sincerely thank you for your diligent work and valuable insights during the review process. We consider your suggestions as valuable guidance and will make every effort to improve and refine our paper. If you have any further comments or suggestions, please feel free to let us know, and we will be more than happy to further improve.

Thank you for your time and expertise!

Best regards,

Taquan Ma