Putting a Price on Nature: Ecosystem Service Value and Ecological Risk in the Dongting Lake Area, China

Round 1

Reviewer 1 Report

This paper explores the relationship between ecosystem service value and ecological risk evolutions. The topic is of great significance. Based on the data of Dongting Lake area in China from 1995 to 2020, this paper employs ArcGIS and Geoda to find that the ecological risk index also decreased slowly over time, with the lowest risk for construction land and the highest for water areas, and Areas with strong partial spatial correlations between ecosystem service value and ecological risk index are mainly distributed in the central water areas and their surrounding areas. The paper is relatively clear and the structure is reasonable. Besides that, the conclusion has practical significance. However, the article needs further improvement in the following aspects.

1.      The abstract needs to be revised. Abstract is on the basis of a simple description of the research background, focus on the research ideas and conclusions, but at present the abstract introduce the research idea more, did not clearly elaborate the research conclusions of this paper.

2.      The literature review needs to be more adequate. It needs to be further supplemented.

3.      The introduction needs to be revised. The introduction lacks of contributions. Therefore, it is suggested that the author listed the contributions in points.

4.      Please read the whole text and correct the citation, grammar, spelling and other mistakes. For example, in line 69, Error! Reference source not found.

Author Response

This paper explores the relationship between ecosystem service value and ecological risk evolutions. The topic is of great significance. Based on the data of Dongting Lake area in China from 1995 to 2020, this paper employs ArcGIS and Geoda to find that the ecological risk index also decreased slowly over time, with the lowest risk for construction land and the highest for water areas, and Areas with strong partial spatial correlations between ecosystem service value and ecological risk index are mainly distributed in the central water areas and their surrounding areas. The paper is relatively clear and the structure is reasonable. Besides that, the conclusion has practical significance. However, the article needs further improvement in the following aspects.

1. The abstract needs to be revised. Abstract is on the basis of a simple description of the research background, focus on the research ideas and conclusions, but at present the abstract introduce the research idea more, did not clearly elaborate the research conclusions of this paper.

The abstract has been revised as follow:

Abstract: Understanding the relationship between ecosystem service value and ecological risk evolutions holds great theoretical and practical significance, as it helps ensure quality management of ecosystems and the sustainable development of human–land system interactions. We analyzed this relationship in the Dongting Lake area in China from 1995 to 2020 using data from remote sensing-interpreted land use with ArcGIS and Geoda. We used the equivalent factor method to estimate the ecosystem service value, constructed a landscape ecological risk index to quantitatively describe the ecological risk of Dongting Lake, and analyzed their correlation. The results show that: （1）Over the last 25 years, the ecosystem service value decreased by 31.588 billion yuan, with higher values in the middle of the area and lower values in the surroundings. The highest value was found in forested land and the lowest was for unutilized land. （2）The ecological risk index also decreased slowly over time. From the perspective of single land use type, the ecological risk value of construction land was the lowest, followed by woodland, grassland, cultivated land, with water area the highest. The ecological risk level presents the distribution state of whole piece and local aggregation. （3）The ecological risk index in Dongting Lake area demonstrated positive spatial correlation, and the spatial agglomeration of land with similar risk levels showed a decreasing trend. Areas with strong partial spatial correlations between ecosystem service value and ecological risk index are mainly distributed in the central water areas and their surrounding areas. This study investigates the rational utilization of land resources, and the sustainable development of regional ecological security in Dongting Lake area.

 

2. The literature review needs to be more adequate. It needs to be further supplemented.

Yes, we have added a number of references as follows:

13. Liu Y.; Failler P.; Liu Z.; Impact of Environmental Regulations on Energy Efficiency: A Case Study of China’s Air Pollution Prevention and Control Action Plan. Sustainability 2022, 14(6):3168.
14. Li, J.; Gao, M.; Spatiotemporal evolution and correlation analysis of ecosystem service values and ecological risk in Binzhou. Acta Ecologica Sinica 2019, 39, 7815-7827.

 

3.  The introduction needs to be revised. The introduction lacks of contributions. Therefore, it is suggested that the author listed the contributions in points.

We have revised the introduction as follows:

1. Introduction

Ecosystem service value and ecological risk are important types of ecological environmental assessments, which are closely related to ecological security. These assessments represent the embodiment of sustainable development of a complex human–land system [1] and can also help to ensure the successful growth of the social economy [2, 3]. In recent years, there has been continuous destruction of the ecological environment along with a gradual weakening of ecological service function [4, 5] due to natural hazards caused by global climate change [6, 7], accelerated population migration caused by the promotion of integration of urban and rural development [8-10], and the expansion of space occupation caused by the continuous gathering of various spatial elements [11]. The Sustainable Development Goals (SDGs) of the United Nations clearly set out to protect, restore and promote the sustainable use of terrestrial ecosystem and sustainable forest management, to prevent and control desertification, and to stop and reverse land degradation and curb the loss of biological diversity. China has made good progress in implementing SDGs; but the ecological environment is remain a challenge for China's realization of the 2030 strategic goal of sustainable development [12, 13]. Thus, preserving the ecological environment and ensuring ecological security have become common global problems, and have attracted widespread attention to strengthen the construction of ecological civilization [14-17].

There has been substantial research focused on the assessment of ecosystem services value and landscape risk, including the introduction of ecosystem services into the assessment of ecological risks for development and improvement. Ecosystem services have been evaluated from different perspectives such as regional scope and time scale [18, 19], and several studies have demonstrated that the forest coverage rate [20], landscape pattern [21], topographic features [22], and land use structure [23] are the main factors affecting ecosystem services. Based on the landscape ecological risk assessment (ESRISK) framework [24], some constructed an ecological security pattern [25] based on ecosystem services. In one study, ecological service degradation was considered a sign of loss, and the researchers constructed a probability representation index system from the dimensions of terrain, human behavior, ecological resilience, and landscape vulnerability [26]. The fuzzy comprehensive evaluation method [27], spatial auto-correlation analysis [28], and extensive application of the geographic information system (GIS) [29] have also been used to conduct comprehensive research on ecosystem service value and landscape ecological risk. It is also necessary to incorporate ecosystem services into an environmental risk management program and to determine ecological risks according to the ecosystem value and function [30, 31].

Based on past research, we have proposed management strategies for areas with different risk levels. Overall, eco-support products and services, the value assessment of which form the base of decision-making for ecological protection, ecological regionalization, economic accounting of the ecological environment, and ecological compensation, were directly or indirectly obtained through the structure, process, and function of an ecosystem [32-36]. Ecological risk assessment involves evaluating the possibility of ecological effects caused by exposure to multiple risk stressors of the ecosystem and its components, which then forms the premise of risk control [37-40]. Although numerous studies have estimated the ecological service value and its distribution in time and space, research focusing on the effective correlation between the change of the ecological environment and the sustainable development of the system is relatively sparse. Effective analysis would need to consider the evolution of ecological service value and risks to propose management strategies for different risk levels through assessing their correlations.

4. Please read the whole text and correct the citation, grammar, spelling and other mistakes. For example, in line 69, Error! Reference source not found.

We have revised the paper to eliminate grammar, spelling, and other errors.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments for author File: Comments.pdf

Author Response

Review Report I had the opportunity to read and review the manuscript entitled “Ecosystem Service Value, Evolution of Ecological Risk, and Their Correlation in the Dongting Lake Area, China” (ijerph2228729). The manuscript's intent is to evaluate the relationship between ecosystem service value and ecological risk evolutions in the Dongting Lake area in China from 1995 to 2020 with ArcGIS and Geoda. This research contributes to providing the rational utilization of land resources, regional ecological security, and sustainable development of the Dongting Lake area. I felt confident that the authors performed actual and careful spatial data processing. However, I have to point out that the topic of the manuscript is similar to the article “Li, J.; Gao, M. Spatiotemporal evolution and correlation analysis of ecosystem service values and ecological risk in Binzhou. Acta Ecologica Sinica 2019, 39, 7815-7827”. So, the innovation of this manuscript is not prominent. I recommend that a major revision is warranted. I ask that the authors to explain my concerns and specifically address each of my comments in their response. My review below suggests some improvements.

1. Title: The title should be reconsidered. The phrase “Ecosystem Service Value” and the phrase “Evolution of Ecological Risk” are not in a coordinate relationship appropriately.

Thank you for this suggestion. We have revised the title: Putting a Price on Nature: Ecosystem Service Value and Eco-logical Risk in the Dongting Lake Area, China

 

2. Keywords: Maybe one or two more keywords should be considered adding.

Yes, we have added a keyword: spatial characteristics

 

3. Introduction: 1) The review is not organized enough, the connection between the first and second paragraphs is not strong. 2) The innovation of the article is located in “research focusing on the effective correlation between the change of the ecological environment and the sustainable development of the system is relatively sparse”. More detailed explain should be made by distinguishing this manuscript and the article “Spatiotemporal evolution and correlation analysis of ecosystem service values and ecological risk in Binzhou”.

1) Thank you for this suggestion. We have rewritten the introduction as follows:

Ecosystem service value and ecological risk are important types of ecological environmental assessments, which are closely related to ecological security. These assessments represent the embodiment of sustainable development of a complex human–land system [1] and can also help to ensure the successful growth of the social economy [2, 3]. In recent years, there has been continuous destruction of the ecological environment along with a gradual weakening of ecological service function [4, 5] due to natural hazards caused by global climate change [6, 7], accelerated population migration caused by the promotion of integration of urban and rural development [8-10], and the expansion of space occupation caused by the continuous gathering of various spatial elements [11]. The Sustainable Development Goals (SDGs) of the United Nations clearly set out to protect, restore and promote the sustainable use of terrestrial ecosystem and sustainable forest management, to prevent and control desertification, and to stop and reverse land degradation and curb the loss of biological diversity. China has made good progress in implementing SDGs; but the ecological environment is remain a challenge for China's realization of the 2030 strategic goal of sustainable development [12, 13]. Thus, preserving the ecological environment and ensuring ecological security have become common global problems, and have attracted widespread attention to strengthen the construction of ecological civilization [14-17].

There has been substantial research focused on the assessment of ecosystem services value and landscape risk, including the introduction of ecosystem services into the assessment of ecological risks for development and improvement. Ecosystem services have been evaluated from different perspectives such as regional scope and time scale [18, 19], and several studies have demonstrated that the forest coverage rate [20], landscape pattern [21], topographic features [22], and land use structure [23] are the main factors affecting ecosystem services. Based on the landscape ecological risk assessment (ESRISK) framework [24], some constructed an ecological security pattern [25] based on ecosystem services. In one study, ecological service degradation was considered a sign of loss, and the researchers constructed a probability representation index system from the dimensions of terrain, human behavior, ecological resilience, and landscape vulnerability [26]. The fuzzy comprehensive evaluation method [27], spatial auto-correlation analysis [28], and extensive application of the geographic information system (GIS) [29] have also been used to conduct comprehensive research on ecosystem service value and landscape ecological risk. It is also necessary to incorporate ecosystem services into an environmental risk management program and to determine ecological risks according to the ecosystem value and function [30, 31].

 

2) Yes, thanks for your suggestion. And we have added the paper "Spatiotemporal evolution and correlation analysis of ecosystem service values and ecological risk in Binzhou" as a reference.

We have read the paper carefully you recommended and there are 3 differences between the two papers: ① the research area is different, that means different area must have different characteristics ; ② the calculation of data and formula is different, especially in table 1, we showed the calculation formulas and described the meaning in each index, in order to make the calculating process more concrete;  ③ In the correlation part, we selected the paper "Overall spatial autocorrelation and Local spatial autocorrelation". It focused on more details on spatial correlation.

 

4. Materials and Methods: 1) The original resolution of the data of Landsat TM/Enhanced Thematic Mapper (ETM) remote sensing images needs to be explained clearly. 2) Why you choose 5km × 5km grid. It's unclear if this choice was the reason why the changes of spatial autocorrelation are not strong. 3) the part “Assessment of Landscape Ecological Risk” need to add necessary references.

1) In this paper, six remote sensing images of Dongting Lake are used as basic data sources from 1995 to 2020, and we choose Landsat TM images of 1995, 2000 and 2005, Landsat EMT+ images of 2010 and Landsat OLI remote sensing images of 2015 and 2020 as remote sensing images, the distinguish ability of which is 30m×30m.

2) After comprehensively considered the scale effects of the study area and the minimum modifiable unit on the measured results and several tests, we divided the landscape pattern of Dongting Lake into grids of 5km×5km by using Create fishnet, and finally we got 2019 evaluation grids.

3) The correlation between ecosystem services and ecological risks in the Dongting Lake area mainly include overall autocorrelation and partial spatial autocorrelation patterns. The overall autocorrelation of the ecological risk index showed that in the last 25years, the Moran’s I value has been continuously decreasing, especially after the implementation of "4350" project, which aims to return farmland to the lake, build polder land and resettle people to build residential towns, and constantly restore the water area of Dongting Lake area. And it makes the spatial agglomeration of sample plots with similar levels of ecological risk of land use showed an overall decreasing trend. Through bivariate spatial autocorrelation, this study analyzed the spatial correlation between the ecosystem service value and landscape ecological risk index in the Dongting Lake area. The areas showing significant correlations were mainly distributed in the middle of the region, namely the west of Changde City, southwest of Yiyang City, and east of Yueyang City. The water area of Dongting Lake show an obvious high-value/high-risk distribution, whereas most of the surrounding areas showed a low-value/high-risk distribution.

 

5. Results: the grading method and specific grading interval about ecosystem service value should be described.

We use grid analysis method to calculate and analyze the ecosystem service value of each unit in the evaluation cells, and then we obtained the distribution of ecosystem service value in Dongting Lake by center point assignment and spatial interpolation. Finally, we divided the study area into five levels according to the geometric interval classification and combined with the actual situation of the study area, they are low ecosystem service value (0,1), moderately low ecosystem service value (1,2), medium ecosystem service value (2,3), moderately high ecosystem service value (3,4) and high ecosystem service value (4, ∞). (Unit: 100 million yuan)

6. Conclusion: In my opinion, the findings of their correlation and especially its reasons should be discussed.

Yes, we revised the conclusions and discussions in more details in the reasons of correlation part as follows:

4.1. Principal Findings

    The correlation between ecosystem services and ecological risks in the Dongting Lake area mainly include overall autocorrelation and partial spatial autocorrelation patterns. The overall autocorrelation of the ecological risk index showed that in the last 25years, the Moran’s I value has been continuously decreasing, Especially after the implementation of "4350" project, which aims to return farmland to the lake, build polder land and resettle people to build residential towns, and constantly restore the water area of Dongting Lake area. And it makes the spatial agglomeration of sample plots with similar levels of ecological risk of land use showed an overall decreasing trend. Through bivariate spatial autocorrelation, this study analyzed the spatial correlation between the ecosystem service value and landscape ecological risk index in the Dongting Lake area. The areas showing significant correlations were mainly distributed in the middle of the region, namely the west of Changde City, southwest of Yiyang City, and east of Yueyang City. The water area of Dongting Lake show an obvious high-value/high-risk distribution, whereas most of the surrounding areas showed a low-value/high-risk distribution.

4.2. Management Implications

From 1995 to 2020, the ecological risk index of the Dongting Lake area has been decreasing continuously, whereas the value of ecosystem services showed a declining trend, which indicated that urbanization, human activities, climate change, public policies and other impacts were responsible for the change of the ecological environment to a certain extent, and these effects further aggravated the existing challenges in this area. The high and moderately high ecosystem service value areas and the low and moderately low risk areas of Dongting Lake are relatively less affected by human activities and disturbances, but it will be difficult to restore these areas once they have been damaged. Therefore, the industrial layout should be reasonably planned according to ecological suitability. Moreover, focus should be placed on the development of agriculture, forestry, animal husbandry and fishing based on the primary industries, so as to protect the ecological environment while improving economic benefits. In the middle ecosystem service value areas and the middle risk areas of Dongting Lake area, the status quo should be maintained as far as possible to reduce the future ecological risk, the industrial transformation and upgrading should be accelerated according to local conditions, reduce and ban the pollution and resource intensive industries. And the farmland should be returned to forest or grassland to promote sustainable development. Affected by natural conditions and human activities, the low and moderately low ecosystem service value areas and the high and moderately high risk areas in Dongting Lake exhibit the characteristics of low value, high ecological risk, and susceptibility to changes in the ecological environment. Therefore, it is necessary to strengthen the protection of the original landscape, establish an early warning mechanism for ecological risks, formulate standards for ecological restoration and reconstruction, and strengthen ecological security barriers. In addition, relevant government departments should continue to adhere to the strategy of regional ecological environmental protection and sustainable social and economic development, adjust the relationship between resources and the ecological environment, strengthen the protection of ecological conservation areas, implement the delineation and implementation of regional ecological conservation red lines, and strengthen the control over land and space use.

7. English language must be reviewed by a native speaker. Some sentences are strange such as “This study provides investigate the rational utilization of land resources, regional ecological security patterned construction, … …”

One of the authors is a native speaker and it also revised many times for the paper.

The sentence you list was revised to "This study investigates the rational utilization of land resources, and the sustainable development of regional ecological security in Dongting Lake area."

 

Author Response File: Author Response.docx

Reviewer 3 Report

The paper concerns extremly important problems related with the value of ecosystem services (ES) (including the way of evaluation of ES) and ES value correlation with ecological risk for development in relation with land use and landscape ecological quality. So, the interest to the readers should be high. 

Though, the Authors' plan and program of research is well constructed and well done, especially as regards methodological scheme, the reserach results have been quite easy predictable on the base of landscape ecology knowledge. However, it schould be emphasized that presented study  has confirmed some regularities in landsape functionning and it has widened the knowledge on correlation between ES value (quality) and ecological risk for development in the context of land use, landscape pattern, presence of natural ecosystems/highly biologically active surfaces (elements), water elements - less in the context of pollution of environment (the latter was not a main object of research, rather indirectly concerned). Further, the  research results are useful (helpful) for management of the areas in the sustainable way; results are helpful to undestand better functioning of the landscape used / transformed by man.

The methodological approach is worth of empasizing as interesting one, especially regarding the construction of the landscape pattern index (Table 1).

Detailed comments:

Ad subsection 1. INTRODUCTION. The aim of research is not formulated directly (it should be improved). The background of literature is not enough in my opinion, because there is no clear justification for the purpose of such study - no gap has been shown in previous studies. I suggest extending of literature review in the context of presented aim and research.

Line 69 - there is Error...

In general, the subject of the article and presented research are very interesting for scientists and managers of areas, because ecosystem services and ecological risk are still not understood enough - it is still a new "thinking" of landsape and land use in the context of mangement and restoration of environment. So, the paper is worth publishing after minor corrections. 

Author Response

The paper concerns extremly important problems related with the value of ecosystem services (ES) (including the way of evaluation of ES) and ES value correlation with ecological risk for development in relation with land use and landscape ecological quality. So, the interest to the readers should be high. 

Though, the Authors' plan and program of research is well constructed and well done, especially as regards methodological scheme, the reserach results have been quite easy predictable on the base of landscape ecology knowledge. However, it schould be emphasized that presented study has confirmed some regularities in landsape functionning and it has widened the knowledge on correlation between ES value (quality) and ecological risk for development in the context of land use, landscape pattern, presence of natural ecosystems/highly biologically active surfaces (elements), water elements - less in the context of pollution of environment (the latter was not a main object of research, rather indirectly concerned). Further, the  research results are useful (helpful) for management of the areas in the sustainable way; results are helpful to undestand better functioning of the landscape used / transformed by man.

The methodological approach is worth of empasizing as interesting one, especially regarding the construction of the landscape pattern index (Table 1).

Detailed comments:

Ad subsection 1. INTRODUCTION. The aim of research is not formulated directly (it should be improved). The background of literature is not enough in my opinion, because there is no clear justification for the purpose of such study - no gap has been shown in previous studies. I suggest extending of literature review in the context of presented aim and research.

Yes, the introduction has been revised as we have described above.

1. Introduction

Ecosystem service value and ecological risk are important types of ecological environmental assessments, which are closely related to ecological security. These assessments represent the embodiment of sustainable development of a complex human–land system [1] and can also help to ensure the successful growth of the social economy [2, 3]. In recent years, there has been continuous destruction of the ecological environment along with a gradual weakening of ecological service function [4, 5] due to natural hazards caused by global climate change [6, 7], accelerated population migration caused by the promotion of integration of urban and rural development [8-10], and the expansion of space occupation caused by the continuous gathering of various spatial elements [11]. The Sustainable Development Goals (SDGs) of the United Nations clearly set out to protect, restore and promote the sustainable use of terrestrial ecosystem and sustainable forest management, to prevent and control desertification, and to stop and reverse land degradation and curb the loss of biological diversity. China has made good progress in implementing SDGs; but the ecological environment is still a shortcoming in China's realization of the 2030 strategic goal of sustainable development [12, 13]. Thus, preserving the ecological environment and ensuring ecological security have become common global problems, and have attracted widespread attention to strengthen the construction of ecological civilization [14-17].

There have been substantial research focused on the assessment of ecosystem services value and landscape risk, including the introduction of ecosystem services into the assessment of ecological risks for development and improvement. Ecosystem services have been evaluated from different perspectives such as the regional scope and time scale [18, 19], and several studies have demonstrated that the forest coverage rate [20], landscape pattern [21], topographic features [22], and land use structure [23] are the main factors affecting ecosystem services. Based on the landscape ecological risk assessment (ESRISK) framework [24], an ecological security pattern was constructed [25] based on ecosystem services. In one study, ecological service degradation was considered a sign of loss, and the researchers constructed a probability representation index system from the dimensions of terrain, human behavior, ecological resilience, and landscape vulnerability [26]. The fuzzy comprehensive evaluation method [27], spatial auto-correlation analysis [28], and extensive application of the geographic information system (GIS) [29] have also been used to conduct comprehensive research on ecosystem service value and landscape ecological risk. It is also necessary to incorporate ecosystem services into an environmental risk management program and to determine ecological risks according to the ecosystem value and function [30, 31].

Based on past research, we have proposed management strategies for areas with different risk levels. Overall, eco-support products and services, the value assessment of which form the base of decision-making for ecological protection, ecological regionalization, economic accounting of the ecological environment, and ecological compensation, were directly or indirectly obtained through the structure, process, and function of an ecosystem [32-36]. Ecological risk assessment involves evaluating the possibility of ecological effects caused by exposure to multiple risk stressors of the ecosystem and its components, which then forms the premise of risk control [37-40]. Although numerous studies have estimated the ecological service value and its distribution in time and space, research focusing on the effective correlation between the change of the ecological environment and the sustainable development of the system is relatively sparse. Such analysis should comprehensively consider the evolution of ecological service value and risks, which can then be used to propose management strategies for different risk levels through assessing their correlations.

Line 69 - there is Error...

Yes, we have revised this error and others as well.

In general, the subject of the article and presented research are very interesting for scientists and managers of areas, because ecosystem services and ecological risk are still not understood enough - it is still a new "thinking" of landsape and land use in the context of mangement and restoration of environment. So, the paper is worth publishing after minor corrections. 

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

1.     The title should be reconsidered., it is necessary to highlight this point in the manuscript, if “Putting a Price on Nature” is in title.

2.     The contribution of this paper can be pointed out more clearly in the introduction part.

3.     English language and style are minor spell check required.

Author Response

Thanks for taking time to review our paper and providing so many constructive suggestions. Please find my responses below in BLUE.

1. The title should be reconsidered, it is necessary to highlight this point in the manuscript, if “Putting a Price on Nature” is in title.

Yes, we have explained our new title "Putting a Price on Nature: Ecosystem Service Value andEcological Risk in the Dongting Lake Area, China" in the following paragraph:

As the title of our paper indicates, we have used a landscape ecological risk assessment model to investigate the spatial-temporal variation of the ecological risk index. Our analysis of the correlation between the ecosystem service value and the ecological risk assessment puts a “price” on nature, providing a framework for more efficient utilization of land resources. Doing so will help establish more stable regional ecological security patterns in the Dongting Lake area and propel the sustainable development of regional ecology.

2. The contribution of this paper can be pointed out more clearly in the introduction part.

We have revised the introduction as follows:

Toward this end, in the present study, we used Landsat Thematic Mapper (TM) remote sensing images of the Dongting Lake area in China from 1995 to 2020 as the basic data source to obtain the land cover data of the region through human–computer interactive interpretation. The equivalent factor method and the spatial analysis model were then used to analyze the spatial-temporal distribution and changes of ecosystem services in the Dongting Lake area. As the title of our paper indicates, we have used a landscape ecological risk assessment model to investigate the spatial-temporal variation of the ecological risk index. Our analysis of the correlation between the ecosystem service value and the ecological risk assessment puts a “price” on nature, providing a framework for more efficient utilization of land resources. Doing so will help establish more stable regional ecological security patterns in the Dongting Lake area and propel the sustainable development of regional ecology.

3. English language and style are minor spell check required.

We have revised the paper and checked the spelling.