Spatio-Temporal Evolution of Ecological Sensitivity in the Desert of China from 1981 to 2022
Round 1
Reviewer 1 Report
The paper titled Spatio-temporal evolution of ecological sensitivity in the desert of China from 1981-2022 represents a major contribution to the field of ecology – ecological sensitivity, and ecological security, especially in sandy land. This study used principal component analysis to build an ecological sensitivity evaluation index system and analyzed the spatial and temporal evolution characteristics of ecological sensitivity in the area in the past four decades. Also, this study examined the influence of the five aspects (topography, climate, hydrology, soil, and vegetation), and create the background conditions for the distribution and change of ecological sensitivity in China's desert areas.
The authors pointed out that this research aims to provide scientific references for desert management and ecological restoration in semi-arid and arid areas in northern China.
This topic is important, original, and relevant in this field of research. The methodology used is adequate for this type of research.
Quotations are relevant, and the references are appropriate, which is very important for further research. The research design is appropriate, and the methods are adequately described. The results are presented adequately and comprehensibly. All the figures and the table are well-presented and clear. There is no need to correct any of them.
The conclusion is supported by the results, and they are consistent with the evidence and arguments presented in the manuscript. The suggestions presented by the authors in the conclusion are very useful and applicable in many other environments and situations.
The article is acceptable for publication in Sustainability, in the special issue Towards the Sustainable Development Goals: Monitoring, Assessment and Management of Eco-Environmental Space, section Environmental Sustainability and Applications.
Author Response
Thanks to the teacher, in order to make the article more complete, I have modified the article, and I have uploaded the file to modify the content.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Please find attached detailed comments and suggestions.
Comments for author File: Comments.pdf
Editing of English language required
Author Response
Thanks to the teacher’s advice, I have revised the article.
Point 1: Page 1-2: The introduction would benefit from incorporating references from the international literature that discuss or propose relevant indicators, the factors commonly used, and the reasons behind their frequent usage. Exploring the indicators used in other studies, helps establish a foundation for the research and allows for comparisons with previous findings. It also aids in identifying gaps in the literature that the current study aims to address. To strengthen the introduction, it is important to highlight the significance of incorporating international literature. Doing so helps establish a global perspective, acknowledges the contributions of previous research, and provides a solid framework for the current study.
Response 1: Thanks to the expert teacher's advice, the introduction of the research area should better show the purpose of the research. In order to have a better global vision, I read the international literature, reorganized the selected indicators and research methods, and sorted out the introduction, as follows:
Ecological sensitivity refers to the sensitivity of the ecosystem to various adverse factors when it is restricted by the natural environment and human activities. It can not only reflect the susceptibility of environmental imbalance, but also identify the intrinsic relationship of various influencing factors within the ecosystem [1,2]. With the rapid development of population and social economy, the scope and intensity of influence of human activities on the natural environment and ecosystem are increasing. The intensification of desertification can be used to drastically reduce the space of human production and living, restricting the coordinated and sustainable development of the local environment and the social economy [3]. Ecological sensitivity evaluation can effectively identify the quality and stability of the potential ecological environment, which is of great guiding significance for the rational use and protection of desert resources, and also provides scientific reference for the construction and management of China's desert environment [4].
At present, scholars have mainly studied the spatial and temporal characteristics of ecological sensitivity in regions, basins, cities and countries based on an evaluation index system [5-8]. In terms of the selection of the evaluation index system, scholars select different indicators according to the needs of the research to build the evaluation system, and then reveal the intrinsic correlation of ecosystem changes in the region [9]. They mainly build an ecological sensitivity evaluation index system from the perspective of climate, soil erosion and land desertification [10-12]. Eggermont et al. [13] selected lake sediments and average temperature indicators to build a variety of inference models to explore the spatial and temporal distribution characteristics of the ecological sensitivity of lakes and swamps in the high altitude Rwenzori area. Tsou et al. [14] using remote sensing data and geographic information system technology, geomorphological factors, land use types and other indicators are selected to analyze the ecological sensitivity of Hangzhou, China. These indicator systems are applicable to the study of ecological sensitivity of desertification and land degradation areas. However, the research on ecological sensitivity is still in the stage of exploration and development. There is no standard specification for the selection of indicators, there is uncertainty and arbitrariness, the degree of spatial dependence is high, and the scale effect has a great impact on the accuracy of the research results.
At present, there are many evaluation methods for ecological sensitivity research, such as hierarchical analysis method, coefficient of variation method, expert scoring method, etc. [15-17]. Wu et al. [16] used the objective confirmation method variation coefficient method to determine the weight, and analyzed the ecological sensitivity of Lingbao City, Henan Province from the aspects of soil type and terrain. Wei et al. [7] selected four comprehensive indicators of soil erosion, water content, salinization and desertification, and used the principal component analysis method to explore the characteristics of spatial and temporal changes of the ecological sensitivity of Wuwei City. There are shortcomings in each evaluation method, and the calculation steps are complex and susceptible to subjective factors, and it cannot fully reflect the actual ecological sensitivity in the northern desert area and the details of different sensitive areas. The spatial distance model does not require experts to subjectively judge the size of the weight coefficient, which reduces arbitrariness in the calculation process of the index and considers the amplification and tightening effect of the critical value on the comprehensive index of the system. This can effectively reflect the coordination and integration of the ecological system in the northern desert area.
China's desert has important ecological functions, which are mainly distributed in the northern region [18]. It is not only a natural underground reservoir and a treasure of biodiversity, but is also the second ecological security barrier to protect the north of China [19]. However, the environment of the desert is relatively sensitive. Under the influence of human activities such as overgrazing and reclamation, the balance of regional ecosystems has been destroyed, there has been serious land desertification, and a series of ecological security problems have emerged such as grassland desertification, reduced water conservation capacity, land desertification and soil erosion [20]. These seriously restrict the coordinated development of the social economy and environment [21]. In recent years, the Chinese government has attached great importance to environmental protection and restoration projects, and has successively implemented policies such as returning farmland to grazing, returning forests to grasslands, and ecological compensation, which have significantly improved ecological construction. In summary, taking the northern desert region of China as the research area, this paper selects six sensitivity indicators of topography, meteorology, hydrology, soil, vegetation and land use from the perspective of nature and humanities, builds a comprehensive ecological sensitivity evaluation index system based on the spatial distance model, evaluates the ecological sensitivity of the northern desert region of China from 1981 to 2022, quantitatively reveals the spatial pattern and temporal evolution in the northern desert areas, and provides scientific reference for desert area governance and industrial development.
Point 2: Page 2: It is preferable to have a separate section for the Study Area instead of treating it as a sub-section of Materials and Methods.
Response 2: Thanks to the expert teacher's suggestion, the research area should be a separate part. It is really inappropriate to put it in the materials and methods. I have revised it into a separate section, and the original chapter has also been adjusted. The specific modifications are as follows:
- Introduction
- Study Area
- Materials and Methods
- Results and analysis
- Discussion
- Conclusions
Point 3: Page 3: In Figure 1, a better legend color palette should have been chosen. Blue colors are not recommended for an elevation map that refers to the mainland, especially for high altitudes. Additionally, brown colors correspond to higher elevation rather than lows.
Response 3: Thanks to the expert teacher's suggestion, I have modified the color of the research overview elevation. The lower elevation has been modified to green, and the higher elevation has been modified to brown. The specific modifications are as follows:
Figure1 Distribution map of desert in northern China
Point 4: Lines 93-102: There is a lack of explanation regarding the theoretical basis for selecting these specific indicators. It is important to mention how each of the indicators employed contributes to the overall ecological sensitivity (based on the international literature). The inclusion of this information will enhance the understanding of how these indicators are interconnected and their combined impact on ecological systems. By acknowledging the contributions of each indicator, the research gains a more comprehensive perspective on the ecological sensitivity being examined.
Response 4: Thanks to the expert teacher's advice, this article refers to Guo et al. (Spatio-temporal changes of land desertification sensitivity in the arid region of Northwest China),Wei et al. (Spatio-temporal evolution of land ecological sensitivity in arid inland river basin based on remote Sensing index: A case of Wuwei City in Shiyang River Basin),Li et al. (Spatio-temporal evolution characteristics of terrestrial ecological sensitivity in China) and other scholars, select 6 first level indicators and 15 secondary indicator factors to build an ecological sensitivity evaluation system, the specific modifications are as follows:
3.1 Selection of indicator factors
Ecological sensitivity means that under the influence of natural and human factors, the various elements are spatially interconnected, influenced and mutually restricted to determine the heterogeneity of the spatial and temporal distribution in the northern desert areas [24]. With reference to the research results of ecological sensitivity analysis, combined with the natural, socio-economic conditions and ecological environment characteristics of the research area itself, 15 index factors are selected from six aspects: topography, meteorology, hydrology, soil, vegetation and land use[7,13]. There are three main indicators of topographic ecological sensitivity(TES), namely, elevation, slope direction and slope. The northern desert area has a large longitude span, and its geographical location and environmental characteristics are significantly different. Different altitudes have a certain impact on climatic conditions, vegetation types and soil types, while different slopes and slope directions will directly lead to wind speed, precipitation, sunshine time, soil stability, water conservation capacity and vegetation coverage [24]. Therefore, the three indicators have a certain impact on the ecological sensitivity of the northern desert areas. Climate ecological sensitivity (CES) mainly selects the average annual temperature, average annual precipitation, average annual evaporation and average annual wind speed [7]. The climatic characteristics of different regions are significantly different. Under the joint action of the four climate indicators, it directly affects the hydrothermal balance conditions, soil erosion degree and vegetation coverage in the northern desert area, and then affects the sensitivity of the ecosystem. Hydrological ecological sensitivity (HES) mainly selects rivers, lakes and reservoirs, which not only reflects the dryness of the northern desert area, but also affects the diversity of vegetation and organisms, thus affecting the sensitivity characteristics of the regional environment [25]. Soil ecological sensitivity (SES) mainly selects soil texture, soil type and soil erosion degree. Most of the soil environment in the northern desert area is poor, which can affect the water conservation and vegetation coverage of the research area to a certain extent, thus changing the ecological sensitivity [26-27]. The ecological sensitivity of vegetation (VES) mainly selects two indicators, namely, the normalized vegetation index and the net primary productivity. The vegetation in different regions of the northern desert areas improves and promotes the regional climate, hydrology, soil and other conditions to varying degrees, and has a certain inhibitory effect on the desertification process, thus reducing ecological sensitivity [28-29]. The ecological sensitivity of land use (LUES) is mainly reflected in the impact of human activities. Human activities have two-sided characteristics on the change of the ecological environment, which can not only destroy the original balanced state of the ecological environment, but also promote the coordinated and sustainable development of the regional environment [30-31].
Point 5: Materials and Methods section: The analysis lacks information regarding the spatial unit of analysis of the final ecological sensitivity index. It is crucial to specify whether the results are in raster format and, if so, what the cell size is, or if it is in vector format and specify how the polygons were defined. This information helps readers understand the spatial context and potential limitations associated with the analysis.
Response 5: Thanks to the expert teacher's advice, I have made a clearer introduction to the ecologically sensitive spatial information of the article. The data used in the full text is the raster data for five years in 1981, 1990, 2000, 2010 and 2022. There is a difference in the size of some original grids, and I have resampled it to 1km × 1km. Some of the original data is vector data, which has also been converted into 1km × 1km raster data. The specific modifications are as follows:
The data of five periods in 1981, 1990, 2000, 2010 and 2022 are selected to carry out research. The spatial reference is the Krasovsky coordinate Albers projection, and the spatial resolution of all indicators obtained and calculated through the data source is resampled to 1km × 1km raster data.
Point 6: Lines 104-122: The methodology for defining the weights is missing.
Response 6: Thanks to the teacher's suggestion, in terms of index selection, this article refers to the research results of ecological sensitivity analysis, combines the natural, socio-economic conditions and ecological environment characteristics of the research area itself, and selects 15 index factors from six aspects: terrain, meteorology, hydrology, soil, vegetation and land use. This paper uses the spatial data model to deal with single-factor ecological sensitivity and comprehensive ecological sensitivity factors. The research method of the article has not been explained clearly. I have adjusted the article, and the specific changes are as follows:
3.3 Research Methods
3.3.1 Single-factor ecological sensitivity
European distance is to measure the absolute distance between points in multidimensional space. With objectivity, science and versatility, it has been widely used in various fields. In geography, European distance has been applied to ecological and environmental quality assessment and arid zone detection. The spatial distance model refers to the basic point of the lowest level based on the research objective in multidimensional space, calculates the European distance from each point of the multidimensional space to the reference point of the lowest level, and judges the degree of ecological sensitivity of each single factor by the size of the distance value. This paper uses ArcGIS software to study six primary indicators such as topography, climate, hydrology, soil, vegetation and land use, and uses the extreme difference change method to standardize each secondlevel index, so as to remove the impact of different dimensions on the evaluation results, and build a one-factor ecological sensitivity index model in the northern desert area with the help of the space distance model[32]. The formula is:
(1)
Where S is the single-factor ecological sensitivity; I is the i-th ecological sensitivity factor; Ilow is the lowest value of each ecological sensitivity.
3.3.2 Comprehensive ecological sensitivity
In the current research, in the evaluation of ecological sensitivity, it is mostly to select a certain index, assign different weights to the index, and multi-factors are weighted and superimposed to calculate comprehensive ecological sensitivity. In order to overcome the subjectivity of the traditional empowerment method, this paper uses ArcGIS software to build comprehensive ecological sensitivity in northern desert areas based on the method of spatial distance index, and normalizes the topographic ecological sensitivity, meteorological ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity index respectively. The processed six first-level indicators take their lowest values as the lowest point of spatial comprehensive ecological sensitivity, and calculate the distance from other points to the lowest point of sensitivity in the space. The greater the distance, the lower the sensitivity [33]. The formula is:
(2)
Where P is the comprehensive ecological sensitivity; TES, CES, HES, SES, VES and LUCS represent topographic ecological sensitivity, climate ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity respectively. TESlow, CESlow, HESlow, SESlow, VESlow and LUCSlow are the lowest reference points respectively. Referring to the environment of the northern desert and the natural breakpoint method, the ecological sensitivity of the northern desert area is divided into five categories, namely, extreme sensitivity, severe sensitivity, moderate sensitivity, mild sensitivity and insensitivity.
Point 7: Lines 112-116: The principal components analysis (PCA), as well as the parameters set to the analysis should have been stated.
Response 7: Thanks to the expert teacher for pointing out the error, there is a big error in the comprehensive ecological sensitivity in the evaluation method in the article. This article uses the spatial distance model to explore the spatial change law of ecological sensitivity in 1981-2020, and does not use the principal component analysis. I have modified the content of the article, as follows:
3.3.2 Comprehensive ecological sensitivity
In the current research, in the evaluation of ecological sensitivity, it is mostly to select a certain index, assign different weights to the index, and multi-factors are weighted and superimposed to calculate comprehensive ecological sensitivity. In order to overcome the subjectivity of the traditional empowerment method, this paper uses ArcGIS software to build comprehensive ecological sensitivity in northern desert areas based on the method of spatial distance index, and normalizes the topographic ecological sensitivity, meteorological ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity index respectively. The processed six first-level indicators take their lowest values as the lowest point of spatial comprehensive ecological sensitivity, and calculate the distance from other points to the lowest point of sensitivity in the space. The greater the distance, the lower the sensitivity [33]. The formula is:
(2)
Where P is the comprehensive ecological sensitivity; TES, CES, HES, SES, VES and LUCS represent topographic ecological sensitivity, climate ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity respectively. TESlow, CESlow, HESlow, SESlow, VESlow and LUCSlow are the lowest reference points respectively. Referring to the environment of the northern desert and the natural breakpoint method, the ecological sensitivity of the northern desert area is divided into five categories, namely, extreme sensitivity, severe sensitivity, moderate sensitivity, mild sensitivity and insensitivity.
Point 8: Lines 123-131: The parameters set to the analysis should have been reported. You should specify how the neighbors were defined in spatial autocorrelation analysis; how spatial relationships among spatial units were defined and what distance method was used.
Response 8: Thanks to the expert teacher's suggestion, in order to make the research method of the article easier to understand, I have made a clearer expression of the local spatial autocorrelation analysis of the article, and I have shown the parameters of spatial relationship and distance method in the article. The specific modifications are as follows:
3.3.3 Local spatial autocorrelation
Local spatial autocorrelation represents the correlation of spatial adjacent areas. If there is spatial correlation, its spatial aggregation characteristics can be determined. If it does not exist, it can reflect the spatial correlation phenomenon that may be masked. This paper uses the Moran index to analyze the spatial aggregation degree of comprehensive ecological sensitivity in the northern desert area from 1981 to 2022, and use ArcGIS software to set the spatial relationship to Inverse Distance and the distance method to Euclidean Distance[34]. The formula is:
(3)
Where I is the Moran index; and is the sensitivity mean of the i unit, the sensitivity mean of the j-th evaluation unit and the sensitivity mean of all evaluation units; Wij is the spatial weight matrix; S is the sum of the elements of the spatial weight matrix.
Point 9: Lines 104-131: Please report the software(s) you used to implement the methods (spatial autocorrelation, principal component analysis etc.).
Response 9: Thanks to the expert teacher's advice. In order to make readers understand the content of the article more clearly, I have introduced the software and parameters used in the article, as follows:
- This paper uses ArcGIS software to study six primary indicators such as topography, climate, hydrology, soil, vegetation and land use, and uses the extreme difference change method to standardize each second-level index, so as to remove the impact of different dimensions on the evaluation results, and build a one-factor ecological sensitivity index model in the northern desert area with the help of the space distance model.
- This paper uses ArcGIS software to build comprehensive ecological sensitivity in northern desert areas based on the method of spatial distance index, and normalizes the topographic ecological sensitivity, meteorological ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity index respectively.
- This paper uses the Moran index to analyze the spatial aggregation degree of comprehensive ecological sensitivity in the northern desert area from 1981 to 2022, and use ArcGIS software to set the spatial relationship to Inverse Distance and the distance method to Euclidean Distance.
Point 10: Results section: The principal component analysis results are missing. Reporting the components allows readers to understand how the original variables contribute to each component and how they are weighted in the analysis. By examining the component loadings, one can identify the variables that have the strongest influence on each component. This information provides insights into the underlying structure and relationships within the data.
Response 10: Thanks to the expert teacher's for the mistakes pointed out, there are large errors in the comprehensive ecological sensitivity in the evaluation method in the article. The article mainly refers to Guo et al. (Spatio-temporal changes of land desertification sensitivity in the arid region of Northwest China) and Li et al. (Spatio-temporal evolution characteristics of terrestrial ecological sensitivity in China). This article uses spatial distance to deal with each single-factor ecological sensitivity to avoid large errors in the article due to the lack of indicators. The specific modifications are as follows:
3.3 Research Methods
3.3.1 Single-factor ecological sensitivity
European distance is to measure the absolute distance between points in multidimensional space. With objectivity, science and versatility, it has been widely used in various fields. In geography, European distance has been applied to ecological and environmental quality assessment and arid zone detection. The spatial distance model refers to the basic point of the lowest level based on the research objective in multidimensional space, calculates the European distance from each point of the multidimensional space to the reference point of the lowest level, and judges the degree of ecological sensitivity of each single factor by the size of the distance value. This paper uses ArcGIS software to study six primary indicators such as topography, climate, hydrology, soil, vegetation and land use, and uses the extreme difference change method to standardize each secondlevel index, so as to remove the impact of different dimensions on the evaluation results, and build a one-factor ecological sensitivity index model in the northern desert area with the help of the space distance model[32]. The formula is:
(1)
Where S is the single-factor ecological sensitivity; I is the i-th ecological sensitivity factor; Ilow is the lowest value of each ecological sensitivity.
3.3.2 Comprehensive ecological sensitivity
In the current research, in the evaluation of ecological sensitivity, it is mostly to select a certain index, assign different weights to the index, and multi-factors are weighted and superimposed to calculate comprehensive ecological sensitivity. In order to overcome the subjectivity of the traditional empowerment method, this paper uses ArcGIS software to build comprehensive ecological sensitivity in northern desert areas based on the method of spatial distance index, and normalizes the topographic ecological sensitivity, meteorological ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity index respectively. The processed six first-level indicators take their lowest values as the lowest point of spatial comprehensive ecological sensitivity, and calculate the distance from other points to the lowest point of sensitivity in the space. The greater the distance, the lower the sensitivity [33]. The formula is:
(2)
Where P is the comprehensive ecological sensitivity; TES, CES, HES, SES, VES and LUCS represent topographic ecological sensitivity, climate ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity respectively. TESlow, CESlow, HESlow, SESlow, VESlow and LUCSlow are the lowest reference points respectively. Referring to the environment of the northern desert and the natural breakpoint method, the ecological sensitivity of the northern desert area is divided into five categories, namely, extreme sensitivity, severe sensitivity, moderate sensitivity, mild sensitivity and insensitivity.
Sandy land, grassland and other lands are the main types of land use in the northern desert areas (Figure 2). From 1981 to 2022, the change of land use type is more obvious, with the largest change in grassland (46 016.33 km2), followed by other lands (30 402.17 km2), and relatively small changes in plough (9996.36 km2), forest (1982.75 km2), water (826.15 km2), construction land (1,487.06 km2) and sandy land (2,974.13 km2). From 2000 to 2010, the area used for different types of land changes greatly, and the areas of grassland and water decrease by 19.08% and 15.22%, respectively; the areas of sandy land and other lands increased by 0.47% and 32.78%, respectively. Reductions to water and grassland areas in the eastern part of the study area are mainly due to the increase of plough, forest and construction land area, and the reduced part of the grassland area in the west and middle of the study area is mainly due to the increase inother lands and sandy land area.
There is a significant change between different land use types in the northern desert area from 1981 to 2022 (Figure 3). The grassland transfer area is the highest (74 353.14 km2), followed by the sand transfer area (50 807.97 km2). The areas of grassland transfer into plough, forest, water, construction land and sandy land are relatively high, at 9 673.07 km2, 5 644.62 km2, 651.64 km2, 811.10 km2 and 43 515.81 km2, respectively. The areas of sandy land transfer into grassland and other lands are relatively high, 13 253.18 km2 and 34 643.18 km2, respectively. The area of other lands transfer into water area is 663.87 km2. From 2000 to 2010, the areas of grassland and sandy land transferred out to other land use types are relatively high, at 63 406.32 km2 and 47 354.93 km2, respectively, of which the area of grassland transferred to sandy land is 4.75%, and the area of sandy land transferred to other lands is 4.16%.
The spatial distribution characteristics of single-factor ecological sensitivity are closely related to the geographical location of each desert (Figure 4). Areas with high topographic ecological sensitivity are mainly the Qaidam Basin Desert, Kumukuli Basin Desert and Gonghe Basin Desert located in the Qinghai-Tibet Plateau in the western part of the study area. The area is above 2 700 m above sea level and the sunny slope is relatively high, while the terrain sensitivity of the Gurbantunggut Desert in the west and eastern desert of the study area is low, and the maximum difference in terrain sensitivity in 2022 is 1.176. The climate ecological sensitivity gradually declines from west to east. The ecological sensitivity of the western part of the study area is high, and the maximum value of climate sensitivity in 2022 is 1.008. This is because the region is mainly located in the Eurasian continent and is greatly affected by the Mongolian and Qinghai-Tibet Plateaus. Hydrological ecological sensitivity is mainly related to the distribution of rivers and lakes. The sensitivity of Mu Us Sandy Land and Tengger Desert in the middle of the study area is low. The minimum hydrological sensitivity in 2022 is 0.015. This is due to the superior water conditions in this area, as there are many lakes and rivers. The difference in soil ecological sensitivity is relatively low in the northern desert area. The difference between the maximum and minimum values of soil ecological sensitivity in 2022 is 0.608. This is due to the poor soil background conditions in this area. The soil is mainly made up of loose sand grains, which is not conducive to plant growth, the sand gap is large, precipitation seeps into the ground so it is not easy to form surface runoff, and the surface dry sand layer prevents water evaporation. The vegetation ecological sensitivity decreases from west to east. The ecological sensitivity of the eastern part of the study area is low, and the minimum vegetation sensitivity in 2022 is only 0.002. This is due to the good climatic conditions in the eastern part of the study area, the superior water quality conditions, and the luxuriant plant growth.
Point 11: Discussion section: The discussion does not focus on specific findings, such as the interpretation of outliers (high-low and low-high). Why are outliers located at particular areas? You should explain how they differ from other areas and what properties make them outliers.
Response 11: Thanks to the expert teacher's suggestion, the article only explains the high-high aggregation area and the low-low aggregation area with positive correlation, and the high-low abnormal aggregation area and low-high abnormal aggregation area are incomplete. Therefore, I have revised the article as follows：
The high-low abnormal aggregation areas are mainly in the Taklamakan Desert, the Gurbantonggut Desert, the Badain Jaran Desert and the Tengger Desert. This is mainly due to the poor environment, relatively high ecological sensitivity and relatively weak human activities in the region. The low-high abnormal aggregation areas are mainly in East Sandy Land of the Yellow River and Mu Us Sandy Land. This is due to the relatively good ecological environment in the region, relatively low ecological sensitivity, and is greatly affected by human activities.
Point 12: Discussion section: The possibilities and shortcomings of the methods used, such as the choice of weights in spatial autocorrelation analysis, have not been discussed. According to previous comment, as long as you specify how the neighbors were defined in spatial autocorrelation analysis, you may be able report possible strengths and limitations of the method.
Response 12: Thanks to the advice of expert teachers, the advantages and disadvantages of the missing research method in the article, as well as the overall shortcomings of the article and the future development direction, I pointed out the shortcomings of this research by reading the article Zou. et al. (Spatial-temporal variations of ecological vulnerability in Jilin Province (China), 2000 to 2018), and the specific modifications are as follows：
In this study, the Moran index can be used to distinguish the positive and negative correlations of space, and it cannot further distinguish between the hot spot area and the cold spot area of the positive correlation of the space. Zou et al. is research results also confirmed it [52]. This study explores the ecological governance of the northern desert area and reveals its governance effectiveness. However, the ecological impact of the natural environment and human activities by the northern desert area is a long-term and very complex process, involving ecology, geography, climatology and other disciplines. If you want to practice ecological governance more scientifically and effectively, its specific internal mutual mechanism still needs to be further investigated and studied.
Author Response File: Author Response.pdf
Reviewer 3 Report
In the ‘Introduction’ section lines 37-38, I do not agree with the class ‘research methods’. Research methods is a title for a field of study. So, this designation should be changed or explained in more detail.
In the ‘Data Sources and Processing’ section line 99, please change the words ‘data format’ to ‘spatial reference’ or any other suitable combination of words saying that the information is about projection and coordinate system.
In Figure 3, the letters a, b, c, and d should be moved to the correct locations.
The title of the fourth and last column in Table 1 should be modified to a more suitable one.
The methodology in the ‘Research Methods’ section should be further explained in more details.
In the ‘Spatial Differentiation Characteristics’ section line 201, please change ‘Figure 3’ to ‘Figure 5’.
After reading the paper, I believe that, in the ‘Abstract’ section lines 10-13, the goals and methodology of the work should be re-stated and changed. The authors stated: ‘This paper selects the northern desert as the study area, uses principal component analysis to build an ecological sensitivity evaluation index system, and analyses the spatial and temporal evolution characteristics of ecological sensitivity in the area of nearly 42 years.’ This is incorrect. In the ‘Introduction’ section lines 67-71, the authors stated that: ‘In summary, this paper takes the typical ecologically fragile area of China, in the northern desert as the study area. By building an ecological sensitivity index model for the northern desert region of China, this paper analyzes the spatial pattern and temporal evolution of ecological sensitivity from 1981 to 2022, and provides scientific reference for desert area governance and industrial development. Hence, I believe what is included in the ‘Introduction’ section reflects the goals of the study. Furthermore, where is the principal component analysis? Accordingly, the whole ‘Abstract’ should be re-written.
Author Response
Thanks to the teacher’s advice, I have revised the article.
Point 1: In the ‘Introduction’ section lines 37-38, I do not agree with the class ‘research methods’. Research methods is a title for a field of study. So, this designation should be changed or explained in more detail.
Response 1: Thanks to the expert teacher's suggestion, the word "research method" is used in the introduction, which is indeed incorrect. The hierarchical analysis method belongs to the evaluation method. Therefore, I have adjusted the research method in the introduction, and the specific modifications are as follows:
At present, there are many evaluation methods for ecological sensitivity research, such as hierarchical analysis method, coefficient of variation method, expert scoring method, etc.
Point 2: In the ‘Data Sources and Processing’ section line 99, please change the words ‘data format’ to ‘spatial reference’ or any other suitable combination of words saying that the information is about projection and coordinate system.
Response 2: Thanks to the expert teacher's correction, Krasovsky coordinate Albers projection is a spatial reference, not a data format. I have modified the article, and the specific modifications are as follows:
The spatial reference is the Krasovsky coordinate Albers projection, and the spatial resolution of all indicators obtained and calculated through the data source is resampled to 1km × 1km raster data.
Point 3: In Figure 3, the letters a, b, c, and d should be moved to the correct locations.
Response 3: Thanks to the expert teacher's suggestion, there is an inconsistency between the picture and the letters in figure 3. I have adjusted the a, b, c, d of the corresponding picture, and the specific modifications are as follows:
Figure 3 Dynamic change of land use in deserts area (a. 1981-1990; b. 1990-2000; c. 2000-2010; d. 2010-2022)
Point 4: The title of the fourth and last column in Table 1 should be modified to a more suitable one.
Response 4: Thanks to the expert teacher's suggestion. The last column in Table 1 not only involves the processing methods, but also contains the models applied to the data processing of each indicator. I have modified the article, and the specific modifications are as follows:
Table 1 Indicator source and processing
|
Primary indicators |
Secondary indicators |
Data sources |
Model and methods |
|
Terrain factors |
Elevation |
Geospatial Data Cloud (http://www.gscloud.cn) |
Digital elevation model [7] |
|
Aspect |
|||
|
Slope |
|||
|
Meteorological factors |
Average annual temperature |
China Meteorological Data Network (http:// data.cma.cn) |
Kriging interpolation method [8] |
|
Average annual wind speed |
|||
|
Average annual precipitation |
|||
|
Average annual evaporation |
|||
|
Hydrological factors |
River |
National Geomatics Center of China (http://www.ngcc.cn) |
Spatial distance model [24] |
|
Lake |
Geospatial Data Cloud (http://www.gscloud.cn) |
||
|
Soil factors |
Soil erosion intensity |
World Soil Database (http://www.fao.org) |
Vector data to raster data [24] |
|
Soil type |
Resource and Environmental Science Data Center of the Chinese Academy of Sciences (http://www.resdc.cn) |
||
|
Soil texture |
|||
|
Vegetation factors |
Net primary productivity of vegetation |
NASA website (https://www.nasa.gov) |
CASA model [26] |
|
Vegeration coverage |
Dimidiate pixel model [13] |
||
|
Human factors |
Land use type |
Resource and Environmental Science Data Center of the Chinese Academy of Sciences (http://www.resdc.cn) |
Reclassification [30] |
Point 5: The methodology in the ‘Research Methods’ section should be further explained in more details.
Response 5: Thanks to the expert teacher's suggestion, in order to make it easier for readers to understand the situation of the article, I have made a more detailed description of the research method section, as follows:
3.3 Research Methods
3.3.1 Single-factor ecological sensitivity
European distance is to measure the absolute distance between points in multidimensional space. With objectivity, science and versatility, it has been widely used in various fields. In geography, European distance has been applied to ecological and environmental quality assessment and arid zone detection. The spatial distance model refers to the basic point of the lowest level based on the research objective in multidimensional space, calculates the European distance from each point of the multidimensional space to the reference point of the lowest level, and judges the degree of ecological sensitivity of each single factor by the size of the distance value. This paper uses ArcGIS software to study six primary indicators such as topography, climate, hydrology, soil, vegetation and land use, and uses the extreme difference change method to standardize each secondlevel index, so as to remove the impact of different dimensions on the evaluation results, and build a one-factor ecological sensitivity index model in the northern desert area with the help of the space distance model[32]. The formula is:
(1)
Where S is the single-factor ecological sensitivity; I is the i-th ecological sensitivity factor; Ilow is the lowest value of each ecological sensitivity.
3.3.2 Comprehensive ecological sensitivity
In the current research, in the evaluation of ecological sensitivity, it is mostly to select a certain index, assign different weights to the index, and multi-factors are weighted and superimposed to calculate comprehensive ecological sensitivity. In order to overcome the subjectivity of the traditional empowerment method, this paper uses ArcGIS software to build comprehensive ecological sensitivity in northern desert areas based on the method of spatial distance index, and normalizes the topographic ecological sensitivity, meteorological ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity index respectively. The processed six first-level indicators take their lowest values as the lowest point of spatial comprehensive ecological sensitivity, and calculate the distance from other points to the lowest point of sensitivity in the space. The greater the distance, the lower the sensitivity [33]. The formula is:
(2)
Where P is the comprehensive ecological sensitivity; TES, CES, HES, SES, VES and LUCS represent topographic ecological sensitivity, climate ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity respectively. TESlow, CESlow, HESlow, SESlow, VESlow and LUCSlow are the lowest reference points respectively. Referring to the environment of the northern desert and the natural breakpoint method, the ecological sensitivity of the northern desert area is divided into five categories, namely, extreme sensitivity, severe sensitivity, moderate sensitivity, mild sensitivity and insensitivity.
3.3.3 Local spatial autocorrelation
Local spatial autocorrelation represents the correlation of spatial adjacent areas. If there is spatial correlation, its spatial aggregation characteristics can be determined. If it does not exist, it can reflect the spatial correlation phenomenon that may be masked. This paper uses the Moran index to analyze the spatial aggregation degree of comprehensive ecological sensitivity in the northern desert area from 1981 to 2022, and use ArcGIS software to set the spatial relationship to Inverse Distance and the distance method to Euclidean Distance[34]. The formula is:
(3)
Where I is the Moran index; and is the sensitivity mean of the i unit, the sensitivity mean of the j-th evaluation unit and the sensitivity mean of all evaluation units; Wij is the spatial weight matrix; S is the sum of the elements of the spatial weight matrix.
Point 6: In the ‘Spatial Differentiation Characteristics’ section line 201, please change ‘Figure 3’ to ‘Figure 5’.
Response 6: Thanks to the expert teacher's correction, the figure 3 of the text in section 4.3.1 should be revised to figure 5. The spatial characteristics of the ecological sensitivity of the northern desert in northern China is mainly described in section 4.3.1. The specific modifications are as follows:
From 1981 to 2022, the ecological sensitivity of the northern desert area is characterized by high in the west, low fluctuation in the middle and low in the east, and the ecological sensitivity is variable from west to east (Figure 5).
Point 7: After reading the paper, I believe that, in the ‘Abstract’ section lines 10-13, the goals and methodology of the work should be restated and changed. The authors stated: ‘This paper selects the northern desert as the study area, uses principal component analysis to build an ecological sensitivity evaluation index system, and analyses the spatial and temporal evolution characteristics of ecological sensitivity in the area of nearly 42 years.’ This is incorrect. In the ‘Introduction’ section lines 67-71, the authors stated that: ‘In summary, this paper takes the typical ecologically fragile area of China, in the northern desert as the study area. By building an ecological sensitivity index model for the northern desert region of China, this paper analyzes the spatial pattern and temporal evolution of ecological sensitivity from 1981 to 2022, and provides scientific reference for desert area governance and industrial development. Hence, I believe what is included in the ‘Introduction’ section reflects the goals of the study. Furthermore, where is the principal component analysis? Accordingly, the whole ‘Abstract’ should be re-written.
Response 7: Thanks to the expert teacher's suggestion, I have reorganized and expressed the summary part, and the introduction part has been revised as follows:
Abstract：The northern desert area of China plays an important strategic role in land resource security and national economic development. Research on the spatial and temporal changes of ecological sensitivity can provide scientific reference for desert management and ecological restoration in arid and semi-arid areas in northern China. This paper takes the northern desert area of China as the research area, uses the spatial distance model to build a comprehensive ecological sensitivity evaluation index system, and discusses the spatial and temporal evolution characteristics of ecological sensitivity in the area from 1981 to 2022.The results show that: (1) Land use in the northern desert area is mainly sandy land, grassland and other lands. The respective areas of grassland and other lands transferred to the area of other land use types are 74 353.14 km2 and 50 807.97 km2. The change of area is an important factor affecting the rate of ecological sensitivity change in the northern desert areas. (2) Five aspects, including topography, climate, hydrology, soil and vegetation, influence and restrict each other, and jointly create the background conditions for the distribution and change of ecological sensitivity in China's desert areas. Climate and topography are the most important influencing factors affecting the ecological sensitivity of northern desert areas. Vegetation is the most active and basic factor affecting the ecological sensitivity of northern desert areas. Hydrology and soil have a certain limiting effect on the ecological sensitivity of northern desert areas. (3) The spatial heterogeneity of ecological sensitivity in the northern desert area is significant, showing the characteristics of high volatility in the west, low volatility in the middle and low volatility in the east. (4) Nearly 42 years, ecological sensitivity of the northern desert area shows the characteristics of increasing first and then decreasing. The area of the fluctuation reduction area accounts for 26.34% of the total area of the research area, of which the area of extreme sensitivity and mild sensitivity varies by 11.84% and 65.28% respectively. (5) The spatial aggregation characteristics of ecological sensitivity have changed significantly, and the area of high-high agglomeration areas and low-low agglomeration areas has also been decreasing, indicating that the environment is obviously improving. In the future, we should pay attention to the efficient use of natural resources in the northern desert areas and strengthen the protection of all kinds of land to achieve the sustainable development of the regional environment.
Introduction: In summary, taking the northern desert region of China as the research area, this paper selects six sensitivity indicators of topography, meteorology, hydrology, soil, vegetation and land use from the perspective of nature and humanities, builds a comprehensive ecological sensitivity evaluation index system based on the spatial distance model, evaluates the ecological sensitivity of the northern desert region of China from 1981 to 2022, quantitatively reveals the spatial pattern and temporal evolution in the northern desert areas, and provides scientific reference for desert area governance and industrial development.
Author Response File: Author Response.pdf
Reviewer 4 Report
The study titled "Spatio-temporal Evolution of Ecological Sensitivity in the Desert of China from 1981–2022" addresses an important topic by analysing the ecological sensitivity changes in the northern desert area of China. The strategic significance of this region for land resource security and national economic development further highlights the relevance and importance of the research. The study's objective to provide scientific references for desert management and ecological restoration in the semi-arid and arid areas of northern China is commendable.
However, there are several minor comments regarding the content and structure of the paper:
- The abstract needs to be revised to provide a concise and coherent summary of the study. It currently lacks clarity and coherence due to incomplete sentences and abrupt transitions. Consider revising the abstract to present the research objective, methodology, key findings, and their significance.
- The paper would benefit from a clear and well-defined research methodology section. Provide a detailed description of the data collection process, the specific steps involved in the principal component analysis, and how the ecological sensitivity evaluation index system was constructed. This will enhance the transparency and replicability of the study.
- The results section would benefit from a more detailed presentation and interpretation of the findings. Specifically, elaborate on the implications of the changes in land use patterns (sandy land, grassland, and unused land) and their impact on ecological sensitivity. Additionally, provide a thorough discussion of the five influencing factors (topography, climate, hydrology, soil, and vegetation) and their interrelationships in shaping ecological sensitivity.
- The paper should include a clear discussion section that contextualizes the results within the broader literature on desert management and ecological restoration. Analyze how the findings contribute to existing knowledge and address any gaps in the current understanding of ecological sensitivity in desert regions.
- Consider including spatial maps or figures to visually represent the spatio-temporal evolution of ecological sensitivity in the northern desert area. This would provide readers with a clearer understanding of the patterns and trends observed.
- The conclusion section should be expanded to summarize the main findings, their implications, and potential recommendations for desert management and ecological restoration practices. Additionally, discuss any limitations of the study and propose directions for future research.
- Proofread the entire paper for grammar, spelling, and formatting errors. Ensure that the content is presented in a clear, concise, and cohesive manner.
Addressing these minor comments will significantly improve the clarity, quality, and overall impact of the paper.
Minor editing of English language required
Author Response
Thanks to the teacher’s advice, I have revised the article.
Point 1: The abstract needs to be revised to provide a concise and coherent summary of the study. It currently lacks clarity and coherence due to incomplete sentences and abrupt transitions. Consider revising the abstract to present the research objective, methodology, key findings, and their significance.
Response 1: Thanks to the expert teacher's suggestion, there are indeed problems in the abstract part. I have revised the content of the abstract of the article, so that the purpose, method, main findings and significance of the research are more clearly presented. The specific modifications are as follows:
The northern desert area of China plays an important strategic role in land resource security and national economic development. Research on the spatial and temporal changes of ecological sensitivity can provide scientific reference for desert management and ecological restoration in arid and semi-arid areas in northern China. This paper takes the northern desert area of China as the research area, uses the spatial distance model to build a comprehensive ecological sensitivity evaluation index system, and discusses the spatial and temporal evolution characteristics of ecological sensitivity in the area from 1981 to 2022.The results show that: (1) Land use in the northern desert area is mainly sandy land, grassland and other lands. The respective areas of grassland and other lands transferred to the area of other land use types are 74 353.14 km2 and 50 807.97 km2. The change of area is an important factor affecting the rate of ecological sensitivity change in the northern desert areas. (2) Five aspects, including topography, climate, hydrology, soil and vegetation, influence and restrict each other, and jointly create the background conditions for the distribution and change of ecological sensitivity in China's desert areas. Climate and topography are the most important influencing factors affecting the ecological sensitivity of northern desert areas. Vegetation is the most active and basic factor affecting the ecological sensitivity of northern desert areas. Hydrology and soil have a certain limiting effect on the ecological sensitivity of northern desert areas. (3) The spatial heterogeneity of ecological sensitivity in the northern desert area is significant, showing the characteristics of high volatility in the west, low volatility in the middle and low volatility in the east. (4) Nearly 42 years, ecological sensitivity of the northern desert area shows the characteristics of increasing first and then decreasing. The area of the fluctuation reduction area accounts for 26.34% of the total area of the research area, of which the area of extreme sensitivity and mild sensitivity varies by 11.84% and 65.28% respectively. (5) The spatial aggregation characteristics of ecological sensitivity have changed significantly, and the area of high-high agglomeration areas and low-low agglomeration areas has also been decreasing, indicating that the environment is obviously improving. In the future, we should pay attention to the efficient use of natural resources in the northern desert areas and strengthen the protection of all kinds of land to achieve the sustainable development of the regional environment.
Point 2: The paper would benefit from a clear and well-defined research methodology section. Provide a detailed description of the data collection process, the specific steps involved in the principal component analysis, and how the ecological sensitivity evaluation index system was constructed. This will enhance the transparency and replicability of the study.
Response 2：Thanks to the expert teacher's suggestion, the research method of the article is not very complete. I have supplemented the research method of the article. This study uses the spatial distance model to build a comprehensive ecological sensitivity evaluation index system, and discusses the spatial and temporal evolution characteristics and laws of ecological sensitivity in the area from 1981 to 2022. The specific amendments are as follows:
3.3 Research Methods
3.3.1 Single-factor ecological sensitivity
European distance is to measure the absolute distance between points in multidimensional space. With objectivity, science and versatility, it has been widely used in various fields. In geography, European distance has been applied to ecological and environmental quality assessment and arid zone detection. The spatial distance model refers to the basic point of the lowest level based on the research objective in multidimensional space, calculates the European distance from each point of the multidimensional space to the reference point of the lowest level, and judges the degree of ecological sensitivity of each single factor by the size of the distance value. This paper uses ArcGIS software to study six primary indicators such as topography, climate, hydrology, soil, vegetation and land use, and uses the extreme difference change method to standardize each secondlevel index, so as to remove the impact of different dimensions on the evaluation results, and build a one-factor ecological sensitivity index model in the northern desert area with the help of the space distance model[32]. The formula is:
(1)
Where S is the single-factor ecological sensitivity; I is the i-th ecological sensitivity factor; Ilow is the lowest value of each ecological sensitivity.
3.3.2 Comprehensive ecological sensitivity
In the current research, in the evaluation of ecological sensitivity, it is mostly to select a certain index, assign different weights to the index, and multi-factors are weighted and superimposed to calculate comprehensive ecological sensitivity. In order to overcome the subjectivity of the traditional empowerment method, this paper uses ArcGIS software to build comprehensive ecological sensitivity in northern desert areas based on the method of spatial distance index, and normalizes the topographic ecological sensitivity, meteorological ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity index respectively. The processed six first-level indicators take their lowest values as the lowest point of spatial comprehensive ecological sensitivity, and calculate the distance from other points to the lowest point of sensitivity in the space. The greater the distance, the lower the sensitivity [33]. The formula is:
(2)
Where P is the comprehensive ecological sensitivity; TES, CES, HES, SES, VES and LUCS represent topographic ecological sensitivity, climate ecological sensitivity, hydrological ecological sensitivity, soil ecological sensitivity, vegetation ecological sensitivity and land use ecological sensitivity respectively. TESlow, CESlow, HESlow, SESlow, VESlow and LUCSlow are the lowest reference points respectively. Referring to the environment of the northern desert and the natural breakpoint method, the ecological sensitivity of the northern desert area is divided into five categories, namely, extreme sensitivity, severe sensitivity, moderate sensitivity, mild sensitivity and insensitivity.
3.3.3 Local spatial autocorrelation
Local spatial autocorrelation represents the correlation of spatial adjacent areas. If there is spatial correlation, its spatial aggregation characteristics can be determined. If it does not exist, it can reflect the spatial correlation phenomenon that may be masked. This paper uses the Moran index to analyze the spatial aggregation degree of comprehensive ecological sensitivity in the northern desert area from 1981 to 2022, and use ArcGIS software to set the spatial relationship to Inverse Distance and the distance method to Euclidean Distance[34]. The formula is:
(3)
Where I is the Moran index; and is the sensitivity mean of the i unit, the sensitivity mean of the j-th evaluation unit and the sensitivity mean of all evaluation units; Wij is the spatial weight matrix; S is the sum of the elements of the spatial weight matrix.
Point 3: The results section would benefit from a more detailed presentation and interpretation of the findings. Specifically, elaborate on the implications of the changes in land use patterns (sandy land, grassland, and unused land) and their impact on ecological sensitivity. Additionally, provide a thorough discussion of the five influencing factors (topography, climate, hydrology, soil, and vegetation) and their interrelationships in shaping ecological sensitivity.
Response 3: Thanks to the expert teacher's suggestion, I added the comprehensive ecological sensitivity of the land use model to the discussion, and also discussed the relationship between the ecological sensitivity of topography, climate, hydrology, soil and vegetation. The specific modifications are as follows:
From the perspective of the comprehensive environment system, Topographic fluctuations affect the significant differences in climatic conditions, vegetation cover and soil types of geographical units in desert areas. The desert area is in the inland area with a dry climate, less precipitation and not easy to form rivers. Under the erosion of wind and water, deserted grasslands are gradually formed. The soil in the northern desert area is dominated by wind sand soil and desert soil that is loose and small in size, and is easily eroded by water and wind power, which aggravates the desertification of desert areas. Due to the large area of the northern desert of China, the large difference in the spatial distribution of vegetation is related to factors such as topography and climate. This creates an ecologically sensitive spatial distribution pattern of the northern desert. In general, climate and topography play a direct role in the impact on the ecological sensitivity of the northern desert areas and are the most important influencing factors. Vegetation is the most active and basic factor affecting the ecological sensitivity of the northern desert areas, and high vegetation coverage can inhibit ecological sensitivity.Hydrology and soil have a certain limiting effect on the ecological sensitivity of northern desert areas.
Land use change has a great impact on comprehensive ecological sensitivity. The land use types in the eastern part of the research area are mainly grassland. Its ecological environment is good, and its ecological sensitivity is relatively low, but the interference caused by human production and life to the surrounding environment is the reason for the change of ecological sensitivity. The land use types in the central and western parts of the research area are mainly sandy land and unused land. Due to the poor background conditions of the environment, its ecological sensitivity is also high.
Point 4: The paper should include a clear discussion section that contextualizes the results within the broader literature on desert management and ecological restoration. Analyze how the findings contribute to existing knowledge and address any gaps in the current understanding of ecological sensitivity in desert regions.
Response 4: Thanks to the expert teacher's suggestion, the discussion part of the article lacks suggestions on desert management and ecological restoration management. I have supplemented this part, as follows:
On the whole, the ecological sensitivity of the northern desert area is still at a high level, and the ecological environment management still has a long way to go. For areas with increased ecological sensitivity, ecological environment management projects should be carried out to increase the protection of the environment, reduce the damage of human activities, and prevent the further deterioration of the environment. For areas with less ecological sensitivity, the local governance model should continue to be maintained.
Point 5: Consider including spatial maps or figures to visually represent the spatio-temporal evolution of ecological sensitivity in the northern desert area. This would provide readers with a clearer understanding of the patterns and trends observed.
Response 5: Thanks to the expert teacher's suggestion. In order to make readers more intuitively express the spatial and temporal evolution of ecological sensitivity in the northern desert areas of China, I re-displayed the changes in ecological sensitivity in 1981-1990, 1990-2000, 2000-2010, 2010-2022 and 1980-2020. The specific modifications are as follows:
Figure 6 Temporal change characteristics of ecological sensitivity (a. 1981-1990; b. 1990-2000; c. 2000-2010; d. 2010-2022; e.1981-2022)
Point 6: The conclusion section should be expanded to summarize the main findings, their implications, and potential recommendations for desert management and ecological restoration practices. Additionally, discuss any limitations of the study and propose directions for future research.
Response 6: Thanks to the expert teacher's advice, there are still many shortcomings in the article. I added the desert tube to "5.3 Desert Environmental Management and Restoration" in the discussion section of the article. The suggestions for rationality and ecological recovery are also discussed. At the same time, the limitations of research and the future development direction are discussed. The specific modifications are as follows:
On the whole, the ecological sensitivity of the northern desert area is still at a high level, and the ecological environment management still has a long way to go. For areas with increased ecological sensitivity, ecological environment management projects should be carried out to increase the protection of the environment, reduce the damage of human activities, and prevent the further deterioration of the environment. For areas with less ecological sensitivity, the local governance model should continue to be maintained.
In this study, the Moran index can be used to distinguish the positive and negative correlations of space, and it cannot further distinguish between the hot spot area and the cold spot area of the positive correlation of the space. Zou et al. is research results also confirmed it [52]. This study explores the ecological governance of the northern desert area and reveals its governance effectiveness. However, the ecological impact of the natural environment and human activities by the northern desert area is a long-term and very complex process, involving ecology, geography, climatology and other disciplines. If you want to practice ecological governance more scientifically and effectively, its specific internal mutual mechanism still needs to be further investigated and studied.
Point 7: Proofread the entire paper for grammar, spelling, and formatting errors. Ensure that the content is presented in a clear, concise, and cohesive manner.
Response 7：Thanks to the expert teacher for his advice. There are still many shortcomings in the article. I have corrected the grammar, phrases and spelling of words in the full text, and the proper nouns of the full text have been unified. Most of the content of the article has been modified and uploaded in revision mode.
Author Response File: Author Response.pdf
Reviewer 5 Report
The manuscript titled ‘Spatio-temporal evolution of ecological sensitivity in the desert of China from 1981-2022' is a well written and technically impressive piece of work that will make a valuable contribution to the literature. I have some additional comments that I think if addressed would improve the quality of the manuscript.
1. Human factors are prepared from what data?
2. Table 1. Why are these variables used in this study? Reference?
3. The purpose of the study is not clear in the introduction
4. What is meant by unused areas in Figure 2?
5. In the discussion section, based on your results, what are your restoration suggestions?
Author Response
Thanks to the teacher’s advice, I have revised the article
Point 1: Human factors are prepared from what data?
Response 1: Thanks to the expert teacher's advice, this article refers to Hao et al. (Effects of land use changes on ecological sensitivity of Nnyang River basin in Tibet) and Tang et al. (Construction of ecological corridors in Changli County based on ecological sensitivity and ecosystem service values) article, selected land use as a human factor, the specific modification is as follows:
The land use ecological sensitivity (LUES) is mainly reflected in the impact of human activities. Human activities have two-sided characteristics on the change of the ecological environment, which can not only destroy the original balanced state of the ecological environment, but also promote the coordinated and sustainable development of the regional environment [30-31].
Point 2: Table 1. Why are these variables used in this study? Reference?
Response 2: Thanks to the expert teacher's suggestion, this article refers to the research results of ecological sensitivity analysis, combines the natural, socio-economic conditions and ecological environment characteristics of the research area itself, and selects 15 index factors from six aspects, including topography, meteorology, hydrology, soil, vegetation and land use. For example, Guo et al.(Spatiotemporal changes of land desertification sensitivity in the arid region of Northwest China.) And Li et al.(Spatio-temporal evolution characteristics of terrestrial ecological sensitivity in China) and other scholars. I have sorted out and supplemented the article, and the specific modifications are as follows:
3.1 Selection of indicator factors
Ecological sensitivity means that under the influence of natural and human factors, the various elements are spatially interconnected, influenced and mutually restricted to determine the heterogeneity of the spatial and temporal distribution in the northern desert areas [24]. With reference to the research results of ecological sensitivity analysis, combined with the natural, socio-economic conditions and ecological environment characteristics of the research area itself, 15 index factors are selected from six aspects: topography, meteorology, hydrology, soil, vegetation and land use[7,13]. There are three main indicators of topographic ecological sensitivity (TES), namely, elevation, slope direction and slope. The northern desert area has a large longitude span, and its geographical location and environmental characteristics are significantly different. Different altitudes have a certain impact on climatic conditions, vegetation types and soil types, while different slopes and slope directions will directly lead to wind speed, precipitation, sunshine time, soil stability, water conservation capacity and vegetation coverage [24]. Therefore, the three indicators have a certain impact on the ecological sensitivity of the northern desert areas. Climate ecological sensitivity (CES) mainly selects the average annual temperature, average annual precipitation, average annual evaporation and average annual wind speed [7]. The climatic characteristics of different regions are significantly different. Under the joint action of the four climate indicators, it directly affects the hydrothermal balance conditions, soil erosion degree and vegetation coverage in the northern desert area, and then affects the sensitivity of the ecosystem. Hydrological ecological sensitivity (HES) mainly selects rivers, lakes and reservoirs, which not only reflects the dryness of the northern desert area, but also affects the diversity of vegetation and organisms, thus affecting the sensitivity characteristics of the regional environment [25]. Soil ecological sensitivity (SCS) mainly selects soil texture, soil type and soil erosion degree. Most of the soil environment in the northern desert area is poor, which can affect the water conservation and vegetation coverage of the research area to a certain extent, thus changing the ecological sensitivity [26-27]. The vegetation ecological sensitivity (VES) mainly selects two indicators, namely, the normalized vegetation index and the net primary productivity. The vegetation in different regions of the northern desert areas improves and promotes the regional climate, hydrology, soil and other conditions to varying degrees, and has a certain inhibitory effect on the desertification process, thus reducing ecological sensitivity [28-29]. The land use ecological sensitivity (LUES) is mainly reflected in the impact of human activities. Human activities have two-sided characteristics on the change of the ecological environment, which can not only destroy the original balanced state of the ecological environment, but also promote the coordinated and sustainable development of the regional environment [30-31].
Point 3: The purpose of the study is not clear in the introduction
Response 3: Thanks to the expert teacher's suggestion, the introduction of the research does clarify the purpose of the research. By reading the literature of the predecessors, I have supplemented it, as follows:
With the rapid development of population and social economy, the scope and intensity of influence of human activities on the natural environment and ecosystem are increasing. The intensification of desertification can be used to drastically reduce the space of human production and living, restricting the coordinated and sustainable development of the local environment and the social economy [3]. Ecological sensitivity evaluation can effectively identify the quality and stability of the potential ecological environment, which is of great guiding significance for the rational use and protection of desert resources, and also provides scientific reference for the construction and management of China's desert environment [4].
Point 4: What is meant by unused areas in Figure 2?
Response 4: Thanks to the expert teacher for their advice. In Figure 2, unused land refers to land that has not been developed and used by human beings. In order to make the expression of the article more accurate, I changed the “unused land” to “other lands”, which contains a broader meaning and more accurate expression. The specific modifications are as follows：
1.Abstract: (1) Land use in the northern desert area is mainly sandy land, grassland and other lands. The respective areas of grassland and other lands transferred to the area of other land use types are 74 353.14 km2 and 50 807.97 km2.
2 Results and analysis: Sandy land, grassland and other lands are the main types of land use in the northern desert areas (Figure 2). From 1981 to 2022, the change of land use type is more obvious, with the largest change in grassland (46 016.33 km2), followed by other lands (30 402.17 km2), and relatively small changes in plough (9996.36 km2), forest (1982.75 km2), water (826.15 km2), construction land (1,487.06 km2) and sandy land (2,974.13 km2). From 2000 to 2010, the area used for different types of land changes greatly, and the areas of grassland and water decrease by 19.08% and 15.22%, respectively; the areas of sandy land and other lands increased by 0.47% and 32.78%, respectively. Reductions to water and grassland areas in the eastern part of the study area are mainly due to the increase of plough, forest and construction land area, and the reduced part of the grassland area in the west and middle of the study area is mainly due to the increase in other lands and sandy land area.
There is a significant change between different land use types in the northern desert area from 1981 to 2022 (Figure 3). The grassland transfer area is the highest (74 353.14 km2), followed by the sand transfer area (50 807.97 km2). The areas of grassland transfer into plough, forest, water, construction land and sandy land are relatively high, at 9 673.07 km2, 5 644.62 km2, 651.64 km2, 811.10 km2 and 43 515.81 km2, respectively. The areas of sandy land transfer into grassland and other lands are relatively high, 13 253.18 km2 and 34 643.18 km2, respectively. The area of other lands transfer into water area is 663.87 km2. From 2000 to 2010, the areas of grassland and sandy land transferred out to other land use types are relatively high, at 63 406.32 km2 and 47 354.93 km2, respectively, of which the area of grassland transferred to sandy land is 4.75%, and the area of sandy land transferred to other lands is 4.16%.
Figure 2 Land use types of northern desert area (a. 1981ï¼›b. 1990ï¼›c. 2000ï¼›d. 2010ï¼›e. 2022)
Figure 3 Dynamic change of land use in deserts area (a. 1981-1990; b. 1990-2000; c. 2000-2010; d. 2010-2022)
- Conclusion: In the past 42 years, the land use types in the northern desert areas are mainly sandy land, grassland and other lands, and the areas of grassland and other lands vary greatly. The areas of grassland and other lands transferred to other land use types are 74 353.14 km2 and 50 807.97 km2, respectively. The areas of grassland transferred into plough, forest, water, construction land and sandy land, the area of sandy land transferred into grassland and other lands, and the area of other lands transferred into water are large.
Point 5: In the discussion section, based on your results, what are your restoration suggestions?
Response 5:Thanks to the expert teacher's suggestion, in order to make the discussion part of the article more complete, I have added suggestions for the ecological environment restoration of the research area, as follows:
On the whole, the ecological sensitivity of the northern desert area is still at a high level, and the ecological environment management still has a long way to go. For areas with increased ecological sensitivity, ecological environment management projects should be carried out to increase the protection of the environment, reduce the damage of human activities, and prevent the further deterioration of the environment. For areas with less ecological sensitivity, the local governance model should continue to be maintained.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
I want to thank the you for the time and effort you put in revising the manuscript, as well as for providing detailed responses to my comments and suggestions. I consider the revised manuscript as suitable for publication.
Minor editing of English language required
Author Response
Thanks to the expert teacher's advice, I have further improved the paper.Some of the sentences have been further modified.
Author Response File: Author Response.pdf
Reviewer 3 Report
I have no further comments.
Author Response
Thanks to the expert teacher's advice, I have further improved the paper.Some of the sentences have been further modified.
Author Response File: Author Response.pdf
