Prediction of Climate Change Impacts on the Distribution of an Umbrella Species in Western Sichuan Province, China: Insights from the MaxEnt Model and Circuit Theory

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I generally agree with the acceptance of this paper. However, as far as I know, when using variables such as elevation and land use, which lack future dynamic maps, these cannot be included in models for future predictions. This is because the model is based on statistical relationships between current occurrence data and current variables. For future projections, the same function derived from the current relationships is applied to future conditions, but only for variables with available future data.

In this case, the inclusion of elevation and land use means that your current model relies on these variables, but for future predictions, there is no corresponding data available. How did you address this limitation in your modeling, and how reliable are the results under these circumstances? If I were conducting such a study, I would include only climatic variables, as their corresponding maps are available for future projections.

Author Response

Comment: I generally agree with the acceptance of this paper. However, as far as I know, when using variables such as elevation and land use, which lack future dynamic maps, these cannot be included in models for future predictions. This is because the model is based on statistical relationships between current occurrence data and current variables. For future projections, the same function derived from the current relationships is applied to future conditions, but only for variables with available future data. In this case, the inclusion of elevation and land use means that your current model relies on these variables, but for future predictions, there is no corresponding data available. How did you address this limitation in your modeling, and how reliable are the results under these circumstances? If I were conducting such a study, I would include only climatic variables, as their corresponding maps are available for future projections.

Response: Thank you for the reviewer’s recognition of the paper. The two issues raised by the reviewer are highly professional and reflect concerns that scholars working on ecological prediction models have always been attentive to. Here, we would like to provide further explanation and clarification:

Firstly, regarding the LUCC in future prediction variables: In our study, we took into account the potential changes in future LUCC. Therefore, we did not use static LUCC, but rather LUCC corresponding to the climate scenarios. The future LUCC was simulated by the research team from Tsinghua University based on different RCP scenarios. We have addressed in the manuscript.

It presents like this: “We utilized the Finer Resolution Observation and Monitoring-Global Land Cover (http://data.ess.tsinghua.edu.cn/data/Simulation/) for land use and land cover (LUCC) data from 2010 and the 2070s. The spatial distribution of future LUCC was simulated using a downscaling approach based on the Cellular Automata Model, covering four major climate change scenarios (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5). To maintain consistency with the climate data, we selected 2010 and the 2070s as the key time points for the analysis, and RCP 2.6, RCP 4.5, and RCP 8.5 as the representative climate scenarios for future LUCC changes. ”

Please see the details in line 167-174.

Secondly, regarding the elevation in future prediction variables: We acknowledge that the future elevation cannot be predicted. Generally, if the Earth has not undergone significant geological movements, its elevation characteristics have not changed much in recent centuries. This is why we chose DEM as a static variable in our future predictions. We hope the reviewer understands this choice.

Once again, we appreciate the reviewer’s valuable time spent reviewing the paper. If there are any further questions, please feel free to raise them.

Reviewer 2 Report

Comments and Suggestions for Authors

 

This is a really interesting manuscript on the specific impacts climate change may have on Tibetan brown bears.  The project includes a nice application of the MaxEnt analysis system and its incorporation with Circuit Theory.  However, I am concerned about the GPS locations you used to characterize habitat use of the bears.  It is a small sample size.  The mixture of sources of the GPS points may likely have different assumptions associated with each type of location making the results of analyzing their combination less robust.  Also, you were not able to take into consideration the effects of sex and age of the bears and season of the year on their habitat selection.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.doc

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript submitted for review concerns issues related to climate change, its impact on biodiversity and the importance of paraoleic species in nature conservation. The topic is interesting and worth learning more about. Below are my comments on the manuscript.

The introduction lacks information on umbrella species. After all, the concept of an umbrella species is placed in the title of the manuscript. Therefore, I expect an extensive fragment on this topic in the introduction. The authors present only detailed information on the Tibetan brown bear, and there is no definition and characterization of umbrella species. In addition, there is too much general and widely known information on climate change and its impact on biodiversity. Information on the specific issue discussed in the manuscript should be included. I expect a photo of the studied object to be included. The location of the research area should start with a more general map - the world, the country, and only at the end a map of the specific research area. In this form, for me as a foreigner, this map does not show anything and I do not know where the research was conducted. The maps provided are too small and hard to read. Consider moving some of the maps to supplementary materials.

Author Response

Comment: The manuscript submitted for review concerns issues related to climate change, its impact on biodiversity and the importance of paraoleic species in nature conservation. The topic is interesting and worth learning more about. Below are my comments on the manuscript.

Response: Thank you very much for your valuable time and thoughtful comments on our manuscript. We sincerely appreciate your recognition of the significance of the topic. We have carefully considered your feedback and revised the manuscript accordingly to improve its clarity and scientific rigor. Below, we provide detailed responses to your specific comments and outline the changes we have made in the revised version.

Comment: The introduction lacks information on umbrella species. After all, the concept of an umbrella species is placed in the title of the manuscript. Therefore, I expect an extensive fragment on this topic in the introduction. The authors present only detailed information on the Tibetan brown bear, and there is no definition and characterization of umbrella species.

Response: Thank you for valuable comments. We have updated the Introduction according to your suggestions.

Now it goes like this: “An umbrella species is one whose protection indirectly benefits the conservation of a broader range of coexisting species and their habitats by ensuring the preservation of ecological processes and biodiversity across large landscapes. The Tibetan brown bear (Ursus arctos pruinosus), as a high-altitude apex predator with specialized habitat requirements and wide-ranging behavior, serves as an effective umbrella species in the fragile alpine ecosystems of the Qinghai-Tibet Plateau and its surrounding areas [7]. Primarily inhabiting high-altitude regions characterized by low temperatures, low oxygen levels, and limited human presence, the Tibetan brown bear is highly sensitive to climate change, yet remains understudied due to its remote and extreme environment [7]. Listed as a second-class protected species in China’s National List of Key Protected Wildlife and in CITES Appendix II, it is particularly vulnerable to environmental changes because of its small population size and dependence on specialized alpine meadow ecosystems.

By focusing on the conservation of Tibetan brown bear habitats, we can simultaneously protect other sympatric species sharing the same ecosystem, such as the Asiatic golden cat (Pardofelis temminckii), snow leopard (Panthera uncia), Asiatic black bear (U. thibetanus), and blue sheep (Pseudois nayaur). Therefore, identifying suitable habitats and ecological corridors for this species can contribute to broader biodiversity conservation in the region. In our research, we employed the MaxEnt model, Circuit Theory, geographic environmental variables, and climate change data to assess both the current and potential future shifts in the distribution and migration corridors. This approach aimed to evaluate the impact of climate change on habitat suitability and movement patterns, providing crucial scientific insights for its conservation. Furthermore, the findings contributed to understanding the broader ecological consequences for other sympatric species in the region, thereby informing a more comprehensive conservation strategy for this high-altitude ecosystem.”

Please see the details in line 106-131.

Comment: In addition, there is too much general and widely known information on climate change and its impact on biodiversity. Information on the specific issue discussed in the manuscript should be included. I expect a photo of the studied object to be included.

Response: Thank you for valuable comments. We have updated the Introduction according to your suggestions.

Now it goes like this: “Global climate change has become one of the most pressing challenges facing humanity today, with profound implications for ecosystems and biodiversity [1]. One of the primary effects of climate change is its impact on species distributions, a critical area of research that has gained considerable attention in recent years [2]. As global temperatures continue to rise and precipitation patterns become more erratic, many species are being forced to migrate to more suitable climatic conditions [3]. These shifts in distribution can significantly disrupt established ecological relationships, particularly as species that have historically coexisted in the same habitats may no longer be found together [4]. Such disruptions can lead to altered species interactions, including competition for resources, changes in predation dynamics, and the breakdown of mutualistic relationships [4]. In some cases, these distribution shifts may result in habitat fragmentation, isolating populations into smaller, disconnected habitat patches [5]. This isolation can prevent gene flow between populations, reducing genetic diversity and limiting the species’ ability to adapt to future environmental changes [6]. Furthermore, some species may not be able to disperse quickly enough to find suitable new habitats, placing them at greater risk of extinction.

Climate change has particularly driven a notable reorganization of species' geographic ranges, with many species migrating toward higher latitudes or altitudes in search of suitable habitats [7]. As species move into previously uninhabited or marginal areas, they face new challenges, such as competition with native species, changes in food availability, and differing environmental conditions. These shifts not only affect individual species but also have broader implications for the structure and functioning of entire ecosystems [8]. For instance, species migration can alter local community composition, potentially leading to the displacement of native species and the introduction of invasive species, which may outcompete local flora and fauna for resources [8]. Moreover, the loss of key species due to habitat loss or shifting environmental conditions can destabilize ecosystem functions, such as pollination, nutrient cycling, and water purification [9]. Disruption of these fundamental processes can trigger cascading effects, threatening the health and resilience of ecosystems, and ultimately jeopardizing the ecosystem services upon which human societies depend.”

Please see the details in line 38-67.

Regarding a photo of the studied object, we have uploaded a brown bear photo which was captured by our camera trap in the Supplementary Material. Please kindly find the supplementary material.

Comment: The location of the research area should start with a more general map - the world, the country, and only at the end a map of the specific research area. In this form, for me as a foreigner, this map does not show anything and I do not know where the research was conducted.” 

Response: Thank you. We have updated the map of study area. Please kindly find the figure 1.

Comment: The maps provided are too small and hard to read. Consider moving some of the maps to supplementary materials.

Response: Thank you for your valuable feedback. We appreciate your suggestion regarding the map sizes. However, as the maps are integral to the key findings of our research, we have kept them within the main manuscript to ensure that these critical results are prominently presented. In response to your comment about the maps being too small, we have already adjusted them to the largest possible size given the constraints of the page layout. We hope this improves readability while maintaining the integrity of the presentation.

Thank you again for your valuable feedback. Please feel free to continue reviewing at your convenience. If you have any further comments, please don’t hesitate to share them. We are more than happy to make additional revisions to improve the quality of the manuscript.

Best,

The authors.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for your responses to the review suggestions.  your revisions of the manuscript are appropriate and sufficient to proceed to publication.

Author Response

Comment: Thank you for your responses to the review suggestions.  your revisions of the manuscript are appropriate and sufficient to proceed to publication.

Response: Thank you for your positive feedback and for considering our revisions appropriate and sufficient. We appreciate the time and effort you have dedicated to reviewing our manuscript, and we are pleased that it meets the standards for publication. Please let us know if any further steps are required.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript was revised according to the reviewer's recommendations.

Author Response

Comment: The manuscript was revised according to the reviewer's recommendations.

Response: Thank you for your precious time and valuable comments.