Impacts of Shrub Encroachment on Vegetation Community and Soil Characteristics in Coastal Wetlands of the Abandoned Yellow River Course

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is contemporary and dealing with an interesting topic. The authors have explored the change in vegetation rather transition in vegetation community with the shrub layer changes and related variation in soil properties. The study design is appropriate and methodology is properly presented. There are a few minor corrections which can be incorporated to make this manuscript more relevant for the publication. The presentation of the manuscript is sound. See the attached pdf file for a few minor comments which can be incorporated to proceed further.

General Comments:

The manuscript is contemporary and dealing with an interesting topic. The main research question of the manuscript was dealing with is how the changes in vegetation community or the expansion of Tamarix chinensis shrub species in the Yellow River course is impacting the blue carbon sequestration potential mediated by the variation cum interaction between plant community composition and soil physicochemical properties. The authors have explored the change in vegetation rather transition in vegetation community with the shrub layer changes and related variation in soil properties. The topic selected in this study is though covered in different studies conducted in different regions of the world but it has novelty with respect to the site selected and the theme of the work is related to the dominance and impact of a single species stand in the riparian region and a soil-plant interaction. Such types of studies are limited, and thus, the manuscript fills the research gap with a proper experimental setup and outcomes can be effective in holistic understanding of the long-term changed in vegetation structure of a region, particularly riparian regions. The findings of the study provides a key information or successive variation in plant community, soil properties and their interaction which have considerable impacts on the blue carbon sequestration potential.

The presentation of the manuscript is sound. The study design is appropriate and methodology is properly presented. However, authors can improve the methodology section, particularly work on data analysis section to provide a few detailed information. For example, LN 141: How soil organic carbon was determined using Elementar Vario? Can be elaborated or explained as generally this instrument is used for estimated total carbon. Also provide information of the normality of the data, if it was tested before performing empirical statistical analyses. In addition, make a minor change in LN 157: Change Pearson to “Pearson’s”.

The results of the study are well presented and easy to understand. It will enrich the content of the journal after publication. However, authors can reduce the redundant information and can precisely present the most relevant points which are discussed in the discussion section to reduce the volume of the manuscript. Though the results are well discussed, there is a minor correction in Discussion, LN 294: Correct ‘which attributable to competitive’ to ‘which is attributable to competitive’. The conclusion section is well presented and it is in line with the research question. Findings of the study support the research hypothesis and well concluded. The studies referred in this study are relevant and align with the theme of the work. There are a few minor corrections which can be incorporated to make this manuscript more relevant for the publication. See the attached pdf file for a few minor comments which can be incorporated to proceed further.

Some specific comments related to the Figures and Tables are as following:

Additional Comments:

Keywords can be arranged alphabetically. The words already present in the title can be replaced with other relevant keywords

Table 2 can be better presented as Supporting Information table.

Figure 2 x- and y-axis labels: Please write the first letter of a word in capital. Give space between parameter and units throughout such figures.

Figures: Kindly check and correctly present the figure caption (e.g., Fig. 4 caption).

Figure 6: Please improve the clarity of the figure.

Overall, the manuscript is interesting and can be accepted for publication after moderate revisions.

 

Comments for author File: Comments.pdf

Author Response

Comments 1: General Comments: The manuscript is contemporary and dealing with an interesting topic. The main research question of the manuscript was dealing with is how the changes in vegetation community or the expansion of Tamarix chinensis shrub species in the Yellow River course is impacting the blue carbon sequestration potential mediated by the variation cum interaction between plant community composition and soil physicochemical properties. The authors have explored the change in vegetation rather transition in vegetation community with the shrub layer changes and related variation in soil properties. The topic selected in this study is though covered in different studies conducted in different regions of the world but it has novelty with respect to the site selected and the theme of the work is related to the dominance and impact of a single species stand in the riparian region and a soil-plant interaction. Such types of studies are limited, and thus, the manuscript fills the research gap with a proper experimental setup and outcomes can be effective in holistic understanding of the long-term changed in vegetation structure of a region, particularly riparian regions. The findings of the study provides a key information or successive variation in plant community, soil properties and their interaction which have considerable impacts on the blue carbon sequestration potential.

Response 1: We would like to thank the reviewer for their thoughtful and constructive feedback. We are pleased to know that the manuscript's topic, methodology, and findings were well-received and appreciated. Below, we have addressed the specific comments (from comment 2 to 5) and suggestions. We hope that these revisions address the concerns raised and improve the overall quality of the manuscript. Once again, we would like to express our gratitude for the reviewer’s insightful feedback. We believe the manuscript is now stronger and more aligned with the expectations for publication.

Comments 2: The presentation of the manuscript is sound. The study design is appropriate and methodology is properly presented. However, authors can improve the methodology section, particularly work on data analysis section to provide a few detailed information. For example, LN 141: How soil organic carbon was determined using Elementar Vario? Can be elaborated or explained as generally this instrument is used for estimated total carbon. Also provide information of the normality of the data, if it was tested before performing empirical statistical analyses. In addition, make a minor change in LN 157: Change Pearson to “Pearson’s”.

Response 2: Thank you for highlighting these points. We have accordingly specified the determination method for soil organic carbon in LN 197 and clarified that normality testing was conducted on the data prior to empirical statistical analysis in LN 209. Additionally, the term "Pearson" has been revised to "Pearson's" in LN 216.

Comments 3: The results of the study are well presented and easy to understand. It will enrich the content of the journal after publication. However, authors can reduce the redundant information and can precisely present the most relevant points which are discussed in the discussion section to reduce the volume of the manuscript.

Response 3: We sincerely appreciate your recognition of this study's research value and your meticulous suggestions. In response to your guidance on streamlining the manuscript, we have optimized language expressions, logical structure, and content necessity. During revision, we relocated discussions on shrub encroachment study areas from Discussion 4.1 to the Introduction (LN 290). Redundant argumentative paragraphs were consolidated and non-core data descriptions were streamlined (e.g., deleting "Our findings reveal distinct response" in LN 290 and trimming "with statistically significant levels (p < 0.05) observed in available nutrient changes" in LN 339), thereby enhancing narrative efficiency.

Comments 4: Though the results are well discussed, there is a minor correction in Discussion, LN 294: Correct ‘which attributable to competitive’ to ‘which is attributable to competitive’. The conclusion section is well presented and it is in line with the research question. Findings of the study support the research hypothesis and well concluded. The studies referred in this study are relevant and align with the theme of the work. There are a few minor corrections which can be incorporated to make this manuscript more relevant for the publication. See the attached pdf file for a few minor comments which can be incorporated to proceed further.

Response 4: We have corrected the grammatical oversight in the Discussion section (LN 348) by revising the phrase “which attributable to competitive” to “which is attributable to competitive,” as highlighted in your comments. Regarding the Conclusion section, we are grateful for your positive assessment of its alignment with the research question and hypothesis. We also appreciate your acknowledgment of the relevance of the cited literature to our study’s theme. All minor technical corrections noted in the PDF have been meticulously implemented.

Comments 5: Additional Comments:

Keywords can be arranged alphabetically. The words already present in the title can be replaced with other relevant keywords. Table 2 can be better presented as Supporting Information table A1 in Appendix A. Figure 2 x- and y-axis labels: Please write the first letter of a word in capital. Give space between parameter and units throughout such figures. Figures: Kindly check and correctly present the figure caption (e.g., Fig. 4 caption). Figure 6: Please improve the clarity of the figure. Overall, the manuscript is interesting and can be accepted for publication after moderate revisions.

Response 5: Thank you for your valuable feedback. We have implemented all suggestions as follows:

Keywords are now alphabetized, and title-overlapping terms replaced with relevant alternatives. Table 2 has been moved to Supporting Information table A1 in Appendix A for conciseness.

In figures, axis labels now capitalize the first letter, with spacing added between parameters and units. All figure captions (including Fig. 4) were verified for consistency. Figure 6 was re-generated with high-resolution files to enhance clarity.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Work written correctly. There are 6 comments marked in the text. These are mainly editorial comments. Units must be written correctly.

Comments for author File: Comments.pdf

Author Response

Comments 1: According to the magazine's editorial policy. The abstract should not exceed 200 words. Instructions to authors should be read.

Response 1: Thank you for your constructive feedback. We sincerely appreciate your attention to the journal’s editorial guidelines and have carefully addressed both concerns. The abstract has been revised to strictly adhere to the 200-word limit, now condensed to 200 words while preserving the study’s core contributions. Key modifications include streamlining background descriptions from the original version to enhance conciseness. The revised version with tracked changes is available in the submission system. We welcome further guidance should additional adjustments be required to meet editorial expectations. This change can be found page 1, and line 13-29.

Comments 2: No d day only

Response 2: We have revised the units to 'day' in the text. This change can be found page 3, and line 185.

Comments 3: Such a sentence is already in the introduction. Here it is unnecessary.

Response 3: The relevant statements regarding the occurrence of shrub encroachment have been removed. This change can be found page 3, and line 188.

Comments 4: State what the abbreviations mean - ITS, TSI, TWL

Response 4: We have added explanations for the abbreviations ITS (Isolated Tamarix shrub), TSI (Tamarix shrub island), and TWL (Tamarix woodland) in Figure 1. This change can be found page 3, and line 191-192.

Comments 5: Please write the units correctly. Correct everywhere.

Response 5: We thank the reviewer for highlighting this issue. The stoichiometric ratios were calculated as atomic ratios after the conversion from mg/kg to mmol/kg from the soil total C, N and P concentrations. We confirm that the unit "mmol/kg" in the manuscript is written and used in accordance with established scientific conventions and journal guidelines. All instances of units in the manuscript have been carefully reviewed and standardized to ensure consistency and adherence to scientific conventions. Corrections have been applied to the text, figures, tables, and supplementary materials as needed.

Comments 6: Explanations of abbreviations must be given below the table.

Response 6: We have now included full definitions for all abbreviations in the table notes. However, to comply with another reviewer’s suggestion to reduce the manuscript length, we have moved this information to Appendix A for clarity and conciseness.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The study aims to investigate the impacts of shrub encroachment on vegetation communities and soil characteristics within the abandoned Yellow River course's coastal wetlands.

The manuscript requires some revisions before it can be considered for publication in Agronomy. Indeed, while the study presents valuable data on the impact of shrub encroachment in coastal wetlands, several areas need improvement to meet the journal's standards.

In particular, here are reported specific comments:

• the abstract effectively summarizes the study, but the keywords could be more specific;
• the introduction could benefit from a more comprehensive review of relevant literature, particularly concerning the mechanisms of shrub encroachment and its impacts on soil biogeochemical processes;
• the novelty could be enhanced by a more thorough comparison with existing literature and a clearer articulation of the study's unique contribution;
• the interpretation of results could be more nuanced, and the ecological implications of the findings should be discussed in greater depth;
• the discussion section should be expanded to provide a more in-depth interpretation of the results. The authors should elaborate on the ecological significance of their findings and discuss them in the context of broader wetland ecosystem dynamics;
• the language and writing quality need improvement. Some sentences are lengthy and complex, reducing readability. Grammatical errors and awkward phrasing should be corrected through careful editing. Please note the following examples
  • "The synergistic effects of global change drivers and shrub encroachment-induced environmental modifications pose substantial threats to coastal wetland ecosystem stability [13]." This sentence could be broken down into two shorter sentences for improved readability, such as: "The synergistic effects of global change drivers and shrub encroachment-induced environmental modifications pose substantial threats to coastal wetland ecosystem stability [13]. These factors can significantly impact the overall health and resilience of these ecosystems."

• "As the material and energy nexus of wetland ecosystems [14], soil physicochemical properties (e.g., pH, salinity, bulk density) and nutrient characteristics (total/available nutrients) jointly govern vegetation succession patterns." The phrase "As the material and energy nexus of wetland ecosystems" is a bit convoluted. It could be rephrased for clarity: "Soil physicochemical properties (e.g., pH, salinity, bulk density) and nutrient characteristics (total/available nutrients) jointly govern vegetation succession patterns, playing a vital role in the material and energy dynamics of wetland ecosystems [14]."

• the tables and figures are generally well-presented, but figure captions could be more detailed.
• the manuscript should be checked thoroughly for compliance with Agronomy's formatting and referencing style;
• the authors should critically review their self-citations and ensure that each one is justified and essential to the manuscript.

The manuscript shows potential for publication in Agronomy but requires the authors to address the identified shortcomings, particularly concerning language, clarity, and the depth of discussion.

Author Response

Comments 1: the abstract effectively summarizes the study, but the keywords could be more specific

Response 1: Thank you for your positive feedback on the abstract and your constructive suggestion regarding the keywords. We have refined the keywords to better align with the study's core contributions and to more precisely highlight its innovative aspects. The updated keywords now emphasize: Coastal wetland; Stoichiometric ratios; Redundancy analysis; Tamarix shrub; Vegeta-tion-soil interaction. This change can be found page 1, and line 30-31.

Comments 2: the introduction could benefit from a more comprehensive review of relevant literature, particularly concerning the mechanisms of shrub encroachment and its impacts on soil biogeochemical processes

Response 2: We sincerely appreciate your constructive feedback regarding the literature review in the Introduction. As suggested, we have expanded the discussion of shrub encroachment mechanisms and their biogeochemical impacts by integrating recent key studies. Specifically, we added the following synthesis: Shrub encroachment significantly alters soil pH, salinity, and C-N cycling processes through mechanisms including modified soil moisture dynamics, organic matter inputs, and root activity. This change can be found page 2, and line 145-147.

Comments 3: the novelty could be enhanced by a more thorough comparison with existing literature and a clearer articulation of the study's unique contribution;

Response 3: We sincerely appreciate the reviewer's constructive feedback regarding enhancing the novelty of our study. In response to this valuable suggestion, we have strengthened our literature synthesis by explicitly identifying two critical knowledge gaps in existing research. Specifically, we highlight that prior coastal shrub research has disproportionately emphasized organic carbon pools, neglecting the pivotal role of soil inorganic carbon (SIC) dynamics in carbonate-rich systems like our study area. This change can be found page 2, and line 147-149. Furthermore, we emphasize that previous regional investigations have predominantly focused on documenting basic soil physicochemical properties changes while failing to quantify cross-scale mechanisms in vegetation-soil interactions .This change can be found page 2, and line 163-164.

Comments 4: the interpretation of results could be more nuanced, and the ecological implications of the findings should be discussed in greater depth;

Response 4: We have incorporated the following statement in the revised manuscript : “Overall, the studies testified shrub encroachment intensifies nutrient limitation through modifications to soil RCNP stoichiometric ratios, thereby compromising wetland ecosystem stability.” This addition explicitly articulates the mechanistic pathway (shrub-induced stoichiometric shifts in R_CNP ratios) driving nutrient limitation, while directly linking these biochemical changes to broader ecosystem-level consequences (wetland stability loss). This change can be found page 12, and line 475-477.

Comments 5: the discussion section should be expanded to provide a more in-depth interpretation of the results. The authors should elaborate on the ecological significance of their findings and discuss them in the context of broader wetland ecosystem dynamics;

Response 5: We sincerely appreciate the reviewer's constructive feedback regarding the need to strengthen ecological interpretations. We have explicitly connected our findings to broader wetland conservation challenges by adding the following statement: “In the context of global coastal wetland degradation, shrub encroachment may paradoxically serve as a potential restoration tool by enhancing structural complexity and C sequestration capacity, with woody plants demonstrating promise for rehabilitating degraded coastal ecosystems.” This revision emphasizes the ecological benefits of shrub encroachment by reframing a traditionally perceived threat as an active restoration strategy. It contextualizes our carbon sequestration findings within global wetland degradation challenges and rehabilitation frameworks, while highlighting the dual implications of vegetation succession for ecosystem management. The added text explicitly links our results to broader wetland dynamics and practical restoration scenarios. This change can be found page 12, and line 487-490.

Comments 6: the language and writing quality need improvement. Some sentences are lengthy and complex, reducing readability. Grammatical errors and awkward phrasing should be corrected through careful editing. Please note the following examples: "The synergistic effects of global change drivers and shrub encroachment-induced environmental modifications pose substantial threats to coastal wetland ecosystem stability [13]." This sentence could be broken down into two shorter sentences for improved readability, such as: "The synergistic effects of global change drivers and shrub encroachment-induced environmental modifications pose substantial threats to coastal wetland ecosystem stability [13]. These factors can significantly impact the overall health and resilience of these ecosystems."

"As the material and energy nexus of wetland ecosystems [14], soil physicochemical properties (e.g., pH, salinity, bulk density) and nutrient characteristics (total/available nutrients) jointly govern vegetation succession patterns." The phrase "As the material and energy nexus of wetland ecosystems" is a bit convoluted. It could be rephrased for clarity: "Soil physicochemical properties (e.g., pH, salinity, bulk density) and nutrient characteristics (total/available nutrients) jointly govern vegetation succession patterns, playing a vital role in the material and energy dynamics of wetland ecosystems [14]."

Response 6: We thank the reviewer for the constructive feedback on writing clarity. We have revised the highlighted sentences as suggested. We have conducted thorough editing to simplify complex phrasing, correct grammatical issues, and improve readability throughout the manuscript.This change can be found page 2, and line 134-139.

Comments 7: the tables and figures are generally well-presented, but figure captions could be more detailed.

Response 7: Thanks. We have updated the captions for Fig. 1 and Supplementary Information Table A1 (originally labeled as Table 2, which was converted to Supporting Information in Appendix A following suggestions from other reviewers) to enhance the clarity and completeness of the figure/table information.

Comments 8: the manuscript should be checked thoroughly for compliance with Agronomy's formatting and referencing style

Response 8: Thank you for your suggestion. We have thoroughly checked the manuscript to ensure full compliance with Agronomy's guidelines.

Comments 9: the authors should critically review their self-citations and ensure that each one is justified and essential to the manuscript.

Response 9: The self-citations in the manuscript serve to corroborate and extend our previous relevant research findings, while also providing a foundation and suggestions for subsequent studies. We have rigorously reviewed all self-citations to ensure that only well-justified and essential references are retained in the manuscript. Thank you for your valuable feedback.

Author Response File: Author Response.docx