The Analysis of NPP Changes under Different Climatic Zones and under Different Land Use Types in Henan Province, 2001–2020
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsI thank the editors for inviting me to review this article. This paper provides valuable insights in examining the trends of net primary productivity (NPP) and its drivers under different climatic zones and land use types in Henan Province, but there may be the following potential shortcomings or limitations that need to be upgraded. My specific comments are as follows.
Major Issues:
1 Justification of methodological choices: Although Theil-Sen median trend analysis and Mann-Kendall trend tests were used, no details were provided as to why these methods were chosen and whether they were best suited to the characteristics of the data in this study.
2. limitations of spatial and temporal resolution: the MODIS dataset used in the article has a spatial resolution of 500 metres and a temporal resolution of one year, which may limit the ability to capture small-scale phenomena.
3. assessment of anthropogenic impacts: the assessment of how human activities affect NPP may not be comprehensive enough, especially the direct impacts of agricultural activities, urbanisation processes, etc. on NPP.
4. The checking report of the article shows that this text article has a high repetition rate, therefore the repetition rate needs to be reduced below 15 to highlight the originality of this article.
Specific Issues:
1. Abstract. The abstract provides a clear overview of the study, but it is recommended that the authors provide more information about the novelty of using the Theil-Sen median trend analysis and Mann-Kendall trend test methods and the rationale for choosing them.
2.Introduction. The introduction effectively sets the context of the study, but it is recommended that the authors further discuss the specificity of Henan Province as a study area and its representation in China's changing ecosystem.
4.Methods section describes the techniques used in the study, but it is recommended that the authors elaborate on the applicability of the Theil-Sen median trend analysis method and the Mann-Kendall trend test in this study, and how they help to reveal specific patterns of NPP change.
5.The results section provides a wealth of information, but it is recommended that the authors use graphs and charts to more visually demonstrate the spatial distribution characteristics and trends of NPP.
6. In the Discussion section, it is recommended that the authors delve deeper into the ecological significance of NPP changes and the potential impacts of these changes on the regional carbon cycle and ecosystem services.
7. The conclusion section clearly summarises the main findings of the study, but suggests that the authors highlight the limitations of the study and directions for future research, particularly the wider implications of NPP changes under different climate zones and land use types.
8. The references are severely lacking and the authors are advised to add and ensure that all cited literature is from the last 5 years and closely related to the study topic.
General Review Comments:
1. the article as a whole provides valuable insights into NPP changes in Henan Province. However, it is recommended that the authors include more notes on methodological limitations and assumptions in the discussion.
2. it is recommended that more detailed information on data collection and analysis methods be added to the results section to improve the transparency and reproducibility of the study.
Author Response
Please refer to the attachment-Response to Reviewer 1 comments .
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral comments: This article focuses on Henan Province's emphasis on carbon neutrality in China, and studies the trends and driving factors of NPP changes in different climate zones and land use types from 2001 to 2020. The paper presents a novel application of the Theil-Sen Median trend analysis method and the Mann-Kendall trend test for analyzing NPP changes, which is a valuable contribution to ecological monitoring and climate change studies. The written language is fine. However, the in-depth insights, academic and scientific nature, and better contribution (to the knowledge system in this field) need continuous revision.
1. In Section 1, it is necessary to clarify the gaps, motivations, and practical significance filled by this research institute.
2. In Section 2, the use of NASA's MODIS data products for NPP, NDVI, and land use data is appropriate. Still, the paper should ensure that the data's spatial and temporal resolutions are adequately justified for the study's objectives. Also, can you provide more details on the processing of data?
3. In Section 3, 1) The source of the method and related applications lack literature citations. 2) The “land use transfer matrix” is too short, and its cause and effect require a more detailed introduction. 3) “Geodetector” needs a clearer explanation of how the temporal weighting function q integrates with the other methods to analyze NPP trends.
4. Three 4.3.2 sections? Can the x-axis in Figure 9 be placed at the top?
5.The differences in sunshine duration factors (daylight time) among different climate zones in Table 3 are significant and require further explanation.
6. Discussion section, it is recommended to list it separately. The paper could be strengthened by a more thorough comparison with existing studies, particularly regarding the NPP trends in different climatic zones and the impact of land use changes on NPP, which would situate the research within the broader scientific context. Discuss the innovation, shortcomings, and underlying reasons behind each discovery compared to previous research.
7. Overall, while the paper employs robust statistical methods, it would be beneficial to include a subsection on the statistical significance of the results, including confidence intervals or p-values, to support the conclusions drawn from the data.
8. The authors have appropriately disclosed that the research received no external funding and have declared no conflicts of interest, which is essential for maintaining the integrity of the study.
9. Texts issues
1. In Line 145,"..., precipitation, and PET, were obtained ...", should be "..., precipitation and PET datasets were obtained ...".
2.In Line 147, “... of 1 kilometer. daylight hours data were provided...” should be “... of 1 kilometer. The daylight hours data were provided...”
Comments on the Quality of English LanguageThe written language is fine
Author Response
Please refer to the attachment-Response to Reviewer 2 comments .
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for Authors1. The study should clarify the discrepancies or error characteristics between the actual on-site characteristics and the NASA MODIS-derived NDVI, NPP, and land use data. It is important for the study to address any potential discrepancies between remote sensing data, such as those derived from NASA's MODIS (Moderate Resolution Imaging Spectroradiometer), and the actual on-site conditions. This includes differences in vegetation indices (NDVI), Net Primary Productivity (NPP), and land use classifications. The study should discuss how these discrepancies might affect the accuracy of the findings and what specific factors could contribute to these errors. Providing a detailed analysis of the error characteristics will enhance the reliability and validity of the study's conclusions.
2. Regarding the study’s results, the authors should identify the potential error factors that could explain discrepancies between the results and the actual on-site conditions, and suggest how future research might address these sources of misinterpretation. The authors need to acknowledge and discuss the possible sources of error that could lead to differences between the study's results and the actual conditions observed in the field. This could include factors such as sensor limitations, atmospheric interference, or inaccuracies in land use classification. Additionally, the study should provide recommendations for future research, focusing on methods or approaches that could minimize these errors and reduce the likelihood of misinterpretation. This will help in refining the methodology and improving the accuracy of similar studies in the future.
3. A careful evaluation of the various factors affecting NPP is necessary. Limiting the study to the impact of different land types and climates on NPP might result in a biased analysis. It is recommended to consider other potential factors as well, and even if the current study does not include data on these factors, an analysis of the uncertainties should be provided. NPP is influenced by a wide range of factors, including but not limited to land type and climate. The study should ensure a comprehensive analysis that considers additional variables, such as soil quality, water availability, and human activities, which might also impact NPP. Focusing solely on land type and climate could lead to an incomplete understanding of the factors influencing NPP, potentially introducing bias into the analysis. If the study does not have access to data on these other factors, it is still crucial to discuss the uncertainties and limitations this imposes on the study’s findings. This will provide a more transparent and holistic view of the results and guide future research efforts to fill these gaps.
Author Response
Please refer to the attachment-Response to Reviewer 3 comments .
Author Response File: Author Response.docx
Reviewer 4 Report
Comments and Suggestions for Authors(1) Net Primary Productivity (NPP) is a key indicator for reflecting changes in the ecological environment. Aiming at the phenomena that research on long-term NPP trends in Henan Province is limited, with most studies employing general mathematical models to explore NPP trends and lacking comparative analysis of NPP trends and driving factors across different climatic zones, the study explored the spatial variation in NPP trends driven by meteorological factors (precipitation, day-light hours, PET, temperature) and vegetation factors using the geographic detector model and examined the quantitative relationship between NPP trends and land use types through land use transition matrices and NPP gain-loss matrices.
(2) Overall, the theme of this manuscript is of good significance and worthy of investigation. The structure was well organized and the Theil-Sen Median trend analysis method to examine the actual positive and negative trends in NPP changes in Henan were reasonable. However, there are still several problems and suggestions required to be addressed as follows.
(3) The Abstract section is too wordy and should be simplified significantly to make it more concise. Moreover, the research gap and background should be summarized and clarified at the beginning of the abstract.
(4) Section 2.1: The specific details of climate parameters in Henan province during the experiment (i.e., from 2001 to 2020) should be provided using a figure or a table, e.g., precipitation and temperature.
(5) The language should be extensive revised as there were many grammatical errors, e.g., in line 22: “The results indicate that …” should be “The results indicated that …”.
Comments on the Quality of English LanguageThe language should be extensive revised as there were many grammatical errors, e.g., in line 22: “The results indicate that …” should be “The results indicated that …”.
Author Response
Please refer to the attachment-Response to Reviewer 4 comments .
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsNo additional comments.
Reviewer 4 Report
Comments and Suggestions for AuthorsAfter carefully reading of the revised manuscript, all comments and suggestions have been addressed. The manuscript has been improved and currently can be considered to be accepted for publication.
