Effects of Soil Nutrient Restoration Aging and Vegetation Recovery in Open Dumps of Cold and Arid Regions in Xinjiang, China
and Weiming Guan 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for Authors1. The paper describes global resource use and the general environmental impacts of mining in the introduction section, but it could be more explicit about how your research fills a gap in the field and why it is important. It is recommended that the background section further highlight the uniqueness of mine ecological restoration in cold and arid environments.
2. suggest additional longitudinal studies to track how correlations between soil nutrients and vegetation change over longer periods of time and under different climatic conditions. 4. line237: mentions changes in vegetation cover, but does not specify whether these changes are statistically significant. 5. The experiment in the manuscript did not have a control group. 6. the grid method was used for soil sampling at five points within the study area, but the exact location and distribution of these five sampling points were not carefully described. 7. Line171-187: It is recommended that the temporal and spatial resolution of data acquisition be stated in the paper. 8. It is recommended that possible errors in the sampling and analysis process be described and corresponding treatment methods be proposed. 7. The description of the results and analysis section is rather lengthy, and it is suggested to streamline the language. 8. Suggestions in the Discussion section begin each subsection with a brief summary of the main points of the section to understand the focus of each section. 9. It is recommended that the authors clearly indicate the limitations of the study, such as the sample size may not be sufficiently representative of the entire region, or the methodology used may not be applicable to other types of mining areas. Comments on the Quality of English LanguageExtensive editing of English language required.
Author Response
Responses to the reviewers' comments
Reviewer #1:
Comment 1: The paper describes global resource use and the general environmental impacts of mining in the introduction section, but it could be more explicit about how your research fills a gap in the field and why it is important. It is recommended that the background section further highlight the uniqueness of mine ecological restoration in cold and arid environments.
Response: Thanks for your comment, we have added the unique description of the cold and dry areas as requested.
“However, the eco-environment of mining areas is a complex system influenced by numerous factors. Monitoring the change of a single factor provides an incomplete picture [15]. Therefore, comprehensive environmental monitoring in mining areas involves assessing multiple aspects, including soil physical and chemical properties, soil nutrients, ecological landscapes, and reclamation effects [16-18]. This multifaceted approach ensures a more holistic understanding of the environmental impacts of mining. Despite the advantages of remote sensing, detailed studies on the potential links between mining activities and vegetation changes, especially at local scales, remain scarce [19]. This gap is particularly significant in cold and arid regions, which account for about 90% of such areas globally and are home to approximately 38% of the world's population [20]. Over the past three decades, mineral resource exploitation in these regions has continued to rise. However, low temperatures and short growing seasons limit natural vegetation recovery, while dry conditions exacerbate water shortages, making restoration efforts slower. The scarcity of water resources often necessitates artificial irrigation or efficient water management technologies. Additionally, mining disrupts the fragile soil structure in these areas, requiring special soil improvement measures to enhance fertility and prevent erosion. The ecosystems in such regions are inherently vulnerable, with limited capacity to recover from external disturbances, so restoration must prioritize ecological balance and avoid introducing unsuitable species [21]. The impact of mining activities on land degradation in these regions has often been overlooked in extensive research. Most existing studies focus on changes in vegetation indices but neglect the potential impacts of mining activities on vegetation phenology [22].”
Comment 2: suggest additional longitudinal studies to track how correlations between soil nutrients and vegetation change over longer periods of time and under different climatic conditions.
Response: Thank you for your comments. Your suggestions are very beneficial to our research. However, our ecological restoration study started in 2018, and the data provided before 2018 cannot reflect the ecological restoration effect from 2018 to 2024. We will add more relevant data according to your suggestions in the later study to make the study more complete.
Comment 3: line237: mentions changes in vegetation cover, but does not specify whether these changes are statistically significant.
Response: Thank you for your comments. Your suggestions are very beneficial to our research. However, our ecological restoration study started in 2018, and the data provided before 2018 cannot reflect the ecological restoration effect from 2018 to 2024. We will add more relevant data according to your suggestions in the later study to make the study more complete.
Comment 4: The experiment in the manuscript did not have a control group
Response: Thank you for your comments. The data of the control group were reflected in the soil sampling data and the correlation analysis heat map. However, it is not over-emphasized in the remote sensing data to avoid the repetition of the data, mainly focusing on the overall data changes with ecological restoration in the region. We will add similar control groups in subsequent studies for clearer comparison.
Comment 5: the grid method was used for soil sampling at five points within the study area, but the exact location and distribution of these five sampling points were not carefully described.
Response: Thanks for your comments. According to your suggestions, we have supplemented the specific coordinates of the sampling points. The selection of sampling points is determined according to the real situation of the mining area.
“The specific coordinates of the sampling points were shown below: original non-vegetation area (87°36’59" E, 43°12'43" N), original vegetation covered area (87°37'41" E, 43°12'56" N), dump (87°36'53" E, 43°13'54" N), green belt of mining ecological area (87°37'30" E, 43°13'40" N), mine restoration demonstration base (87°37'34" E, 43°13'33" N).”
Comment 6: the grid method was used for soil sampling at five points within the study area, but the exact location and distribution of these five sampling points were not carefully described.
Response: Thanks for your comments. According to your suggestions, we have supplemented the specific time and space information of sampling in the paper.
“The specific coordinates of the sampling points were shown below: original non-vegetation area (87°36’59" E, 43°12'43" N), original vegetation covered area (87°37'41" E, 43°12'56" N), dump (87°36'53" E, 43°13'54" N), green belt of mining ecological area (87°37'30" E, 43°13'40" N), mine restoration demonstration base (87°37'34" E, 43°13'33" N). The sampling time was December 1 of the corresponding year.”
Comment 7: It is recommended that possible errors in the sampling and analysis process be described and corresponding treatment methods be proposed.
Response: Thanks for your comments. The soil samples for sampling and analysis may vary due to the difference in sampling area and sampling time. In this study, the method of averaging samples three times was adopted to reduce the occurrence of such errors. The data presented were all the results of averaging data collected three times.
Comment 7: The description of the results and analysis section is rather lengthy, and it is suggested to streamline the language.
Response: Thank you for your comments. According to your suggestions, we have simplified the language of the results and analysis section, deleting nearly 1/8 of the length to make the article more concise
Comment 8: Suggestions in the Discussion section begin each subsection with a brief summary of the main points of the section to understand the focus of each section.
Response: Thank you for your comments. Your suggestion is quite correct, but it seems to be contrary to Comment 7. We have made a large reduction in the results and discussion section as requested by Comment 7. The discussion section at this stage should be more concise and the main points of the subsections can be found quickly
Comment 9: It is recommended that the authors clearly indicate the limitations of the study, such as the sample size may not be sufficiently representative of the entire region, or the methodology used may not be applicable to other types of mining areas.
Response: Thank you for your comments, and as you suggested, a note has been added to the Deficiencies and Prospects section of Section 5.2
“Despite its contributions, this study has several limitations: (1) Although the current regreening method is simple and low-cost, the survival rate of vegetation is low, the self-sustaining ability of the ecosystem is weak, and the recovery time is long (10-20 years); (2) The eco-environment of the cold and arid mining area is fragile, with high temperatures, little precipitation, and intense evaporation in summer. The poor and scarce soil in the mining area affects the growth of vegetation, aggravates soil and water loss, and makes it difficult for the ecosystem to recover; (3) The selection and allocation of native plants have high technical requirements, and most of the vegetation in fragile habitats cannot adapt to it, requiring manual intervention to germinate, but the natural environment stress leads to the natural decline of most species; (4) The sample size of the study may not be adequately representative of the entire region. The ecological restoration methods used in cold and dry mining areas may not be suitable for other types of mining areas; (5) The oversetting of mine restoration goals led to the increase of restoration costs and requires a lot of manual intervention to maintain the effect, and the shortage of water resources becomes the main constraint. Affected by regional resource conditions and restoration area, the capital investment is large, it is difficult to achieve the expected effect without manual intervention, and too much intervention will have adverse effects on the ecosystem.
Therefore, adjustment and improvement measures should be taken in the following aspects:
(1) Future research should explore more effective regreening techniques, such as using drought-resistant species, soil amendments, and optimizing planting times to in-crease vegetation survival rates and reduce recovery time; (2) Future research should explore more effective regreening techniques, such as using drought-resistant species, soil amendments, and optimizing planting times to in-crease vegetation survival rates and reduce recovery time; (3) Future studies should refine protocols for selecting native plants, including seed priming and stress-resistant varieties, to improve adaptability and reduce manual intervention; (4) A larger and more diverse sample size is needed to ensure findings are representative of other mining regions, allowing for tailored restoration approaches across different environments; (5) A larger and more diverse sample size is needed to ensure findings are representative of other mining regions, allowing for tailored restoration approaches across different environments.
Comment 10: Comments on the Quality of English Language. Extensive editing of English language required.
Response: Thank you for your comments. According to your comments, we have carefully checked and modified the full text, but since the modification time given is only 7 days, we cannot do a more detailed inspection, I hope you don't blame us.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe reviewed manuscript (land-3223128) addresses an important problem, which is the restoration of cold and arid open-pit mines. The authors collected soil samples from Heishan open-pit coal mine in Xinjiang, China and analyze the changes in soil nutrients (N, P, K, and OM). Remote sensing generated indices (RSEI and FVC) were obtained to evaluate the effect of the mine restoration. Correlation analysis was used to figure out the relation between soil nutrient content and vegetation coverage. However, the manuscript would be improved if the following points were addressed:
1. Line 119, Figure 1; This figure caption should be modified to include more information regarding the displayed site map.
2. Section 2.1; Please support the presented information with literature.
3. Lines 153:155; It will be better if different sampling points (green belt, mine restoration demonstration base, dump, original vegetation-covered area, and original non-vegetation-covered area) were shown in Figure 1 using different colors or symbols.
4. Sections 2.3 and 2.4; All equations should be supported with references. In addition, it will be better if the data source (Landsat images, …) were presented in section 2.3.
5. Lines 239:241 and 270:271; Is there any reference that supports this classification.
6. Figures 4 and 6; Please check that the total is (100%) for 2018 and 2020 (Figure 4); 2018, 2020 and 2023 (Figure 6).
7. Lines 276:278; There is no information presented before about the variation in surface temperature and humidity?
8. Conclusions; The main findings should be presented in the same order as the main text.
Author Response
Responses to the reviewers' comments
Reviewer #2:
Comment 1: Line 119, Figure 1; This figure caption should be modified to include more information regarding the displayed site map.
Response: Thank you for your comments and guidance. According to your suggestion, we have made the requested changes to Figure 1 and its name to ensure a clear description of the figure. The revised results have been updated in the manuscript:
Figure 1. (a) The provinces map of study area located; (b) the city map of study area located; (c) distribution map of specific terrain and sampling points of mining area.
Comment 2: Section 2.1; Please support the presented information with literature.
Response: Thank you for your comments. The relevant geographic information of the research area mentioned in this section comes from the ecological rectification project report of the mining area in Urumqi. Most of the data are tested by the staff of the local mining area and have certain reference value, while a small part of the data comes from China Geographic Information Network. Prior to this project, previous researchers were unable to publish relevant papers based on this region, so we cannot add references. We are very sorry about that.
Comment 3: Lines 153:155; It will be better if different sampling points (green belt, mine restoration demonstration base, dump, original vegetation-covered area, and original non-vegetation-covered area) were shown in Figure 1 using different colors or symbols.
Response: Thank you for your comments. According to your request, we marked the sample points in Figure 1 with different colors and annotated the text below the picture.
Figure 1. (a) The provinces map of study area located; (b) the city map of study area located; (c) distribution map of specific terrain and sampling points of mining area.
Comment 4: Sections 2.3 and 2.4; All equations should be supported with references. In addition, it will be better if the data source (Landsat images, …) were presented in section 2.3.
Response: Thank you for your comments. According to your request, the corresponding references have been marked in the article. For equations 4,5,6,7,8 and 9, we refer to the research of Wang et al. The reference of equations 1,2,10,11,12 and 13 are the doctoral thesis of Dr. Liu Li from China University of Mining and Technology. However, it cannot be quoted in the article due to the format of the reference. We are very sorry about that. The data used in this paper were obtained from the official website of the United States Geological Survey (USGS) (earthexplorer.usgs.gov).
- Wang, W. Zhou, Y. Guan, J. Wang, R. Ma, Monitoring the ecological restoration effect of land reclamation in open-pit coal mining areas: An exploration of a fusion method based on ZhuHai-1 and Landsat 8 data, Science of the Total Environment 904 (2023) 166324
- 王丽.恢复力视角下矿区植被扰动-损伤-修复综合评价与恢复方案[D].中国矿业大学,2021. DOI:10.27623/d.cnki.gzkyu. 2021.000006.
Comment 5: Lines 239:241 and 270:271; Is there any reference that supports this classification.
Response: Thank you for your comments. Regarding the classification of remote sensing data in these two places, we refer to the research and classification of Liu et al.
- Niu, Y. Li, Remote Sensing Evaluation of Ecological Environment of Anqing City Based on Remote Sensing Ecological Index, The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (2020) 733-737.
Comment 6: Figures 4 and 6; Please check that the total is (100%) for 2018 and 2020 (Figure 4); 2018, 2020 and 2023 (Figure 6).
Response: Thank you for your comments. We have made corrections to the errors in the graph to ensure that the sum is 100%.
Figure 4. FVC percentage of the study area
Figure 6. RSEI percentage of the study area.
Comment 7: Lines 276:278; There is no information presented before about the variation in surface temperature and humidity?
Response: Thank you for your comments. For this part of the research on temperature and humidity, we refer to the research of Hu et al., and add some actual conditions of the mining area for analysis and judgment.
- Xu, F. Xu, T. Lin, Q. Xu, P. Yu, C. Wang, A. Aili, X. Zhao, W. Zhao, P. Zhang, Y. Yang, K. Yuan, A systematic review and comprehensive analysis on ecological restoration of mining areas in the arid region of China: Challenge, capability and reconsideration, Ecological Indicators 154 (2023) 110630.
Comment 8: Conclusions; The main findings should be presented in the same order as the main text.
Response: Thanks for your comments, we have revised the conclusion in accordance with your request.
(1) RSEI and FVC in the Heishan Open-pit showed an overall upward trend over five years, with significant improvements in 2020 due to slope remediation and restoration projects. Air humidity and surface temperature were key factors influencing RSEI and FVC.
(2) In the same restoration period, soil nutrient contents in vegetation mine restora-tion sites were significantly higher than in naturally restored dump soils.
(3) The contents of N, P, K, and OM in the soil increased annually with longer repair times. After five years, these nutrient levels exceeded those of the original vegetation area.
(4) The correlation coefficients between soil nutrient content and vegetation coverage were higher than 0.78, indicating a close and complementary relationship. These findings help clarify the relationship between natural and artificial restoration in cold and arid mining areas, promoting further research and practice in mine restoration.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors1. Please note that in the revised manuscript, all changes are highlighted in different colors to facilitate identification and review.
2. The conclusion section, which is too long and redundant, has been streamlined and refined to ensure that only key and important conclusions are presented.
Comments on the Quality of English LanguageSome paragraphs are lengthy and could be made more concise. Striving for brevity while retaining essential information will help maintain reader engagement.
Author Response
Responses to the reviewers' comments
Reviewer #1:
Comment 1: Please note that in the revised manuscript, all changes are highlighted in different colors to facilitate identification and review.
Response: Thank you for your comments. In accordance with your comments, we have marked the revised paragraphs and statements with different colors as required.
Comment 2: The conclusion section, which is too long and redundant, has been streamlined and refined to ensure that only key and important conclusions are presented.
Response: Thanks for your comments, we have made a large cut to the conclusion section as requested, and the conclusion section is now about 75% of its original length.
Comment 3: Comments on the Quality of English Language. Some paragraphs are lengthy and could be made more concise. Striving for brevity while retaining essential information will help maintain reader engagement.
Response: Thank you for your comments. For most of the long paragraphs, we further cut out repetitive expressions and sentences with no nutrition. We have marked all the modified paragraphs with different colors.
Author Response File: Author Response.docx
