Effects of Afforestation on Soil Organic Carbon and Nitrogen Stocks in the Long Term in Semi-Arid Regions of Türkiye

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The core scientific question addressed in this paper is the impact of long-term afforestation (using black pine as an example) on soil properties, particularly soil organic carbon (SOC) and nitrogen (N) stocks, in semi-arid regions, as well as the driving mechanisms behind these impacts. This scientific question responds to the core needs of combating land degradation and ecological restoration in arid and semi-arid regions, with a particular focus on the long-term effectiveness of afforestation as a carbon sequestration measure, thus holding clear ecological and climatic significance. Specific suggestions，

1. Suggestions on Soil Background Differences and Deepening Mechanistic Interpretation

The paper indeed does not explicitly verify whether the initial soil backgrounds (e.g., SOC, N content, texture) of the afforestation plots in 1968, 1973, 1985, 1996, and 2002 were consistent. It merely defaults to their homogeneity based on "the same region and similar management measures," which may introduce biases.

• Supplement and collect initial soil data for each afforestation year (e.g., soil census data before afforestation in 1968, baseline survey records during afforestation in 1973). If historical data are missing, calibration can be performed using soil properties of adjacent non-afforested plots (e.g., "native degraded land" in the study area not subjected to afforestation) to quantify the impact of initial differences on subsequent results.
• Integrate multiple driving factors using Structural Equation Modeling (SEM): Treat soil background (initial SOC, N), meteorological factors (annual precipitation, temperature), stand age, soil preparation intensity (tillage depth, frequency), and soil physicochemical properties (bulk density, CEC, clay content) as exogenous variables, and SOC and N stocks as endogenous variables. Quantify the direct/indirect effects and contribution ratios of each factor, such as verifying the path intensity of "soil preparation → reduced bulk density → SOC accumulation," to enhance the depth of mechanistic interpretation.

2. Suggestions on Converting Tables 2–4 to Stacked Bar Charts

This suggestion can significantly improve data visualization. Tables 2 (CEC, pH, EC, etc.), 3 (soil texture, bulk density), and 4 (C and N contents) contain numerous depth-specific and treatment-specific values, and textual tables may obscure key differences.

• Design of stacked bar charts: Use "treatment type (afforested/non-afforested) × year" as the x-axis, soil depth (0–10 cm to 40–50 cm) as stacked layers, and parameter values (e.g., SOC content) as the y-axis. Distinguish depths by different colors to intuitively show: ① Differences between afforested and non-afforested plots at the same depth (e.g., comparison of 0–10 cm SOC in afforested and non-afforested plots in 1996); ② Proportional distribution of each depth within a single treatment (e.g., the proportion of CEC in 0–10 cm vs. 40–50 cm in 1968 afforested plots).
• Advantages: It allows quick identification of "treatment effects along the depth gradient" (e.g., whether SOC is mainly accumulated in the topsoil) and "temporal trends across years" (e.g., whether the vertical distribution of clay content changed from 1968 to 2002), enhancing data readability.

3. Suggestions on Converting Figures 3 and 4 to Stacked Bar Charts

This suggestion can simplify the chart structure and highlight core trends. The current Figures  (SOC, inorganic carbon, total carbon stocks) and 4 (N stocks) are split by depth, with five subplots that are scattered and difficult to compare holistically.

Please revise it as Q2.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript entitled "Does Afforestation Increase Soil Organic Carbon and Nitrogen Stocks in the Long Term in Semi-arid Regions of Türkiye?" is a study on exploring the soil C sequestration potential of black pine plantations in the long term in the Semi-arid Regions of Türkiye. The topic/theme of the study is not novel as there are a number of studies which have explored the role of plantation in different regions of the world, including arid and semi-arid regions. However, the work has some merit related to site specificity. The work is very extensive. Authors have considered five plantations events viz., 1968, 1973, 1985, 1996, and 2002 which reflect the plantation year and an adjacent plot which was tilled during that particular time of afforestation was selected for comparison, but remain open land throughout the time period of afforestation. At each site, three plots of 20x20 m was selected for exploring the soil properties such as pH, EC, carbonate or alkalinity content, total C, inorganic and organic C, total N etc. The findings are statistically analyzed and results are extensively presented. The findings of the study are extensively presented and sometimes it seems difficult to understand the crux of the findings. Authors need to substantially work on the manuscript to make it more clear in presentation. The manuscript needs a major rehaul in terms of sentence formulation and presentation of data, tables and figures. Detailed comments are outlines in the attached pdf file. Specifically,

1. The title of the manuscript must be changed as it is first of all assertive in nature and since a number of studies have been done on related topic and afforestation has been established as a C sequestration tool, so no need to pose this question in the title itself. It decrease the strength and novelty of the manuscript. Authors can choose another title which directly reflect the findings of the study.
2. The last paragraph of introduction, particularly related to research gap, hypothesis and objectives can be better presented.
3. The Material and methods section can be elaborated and presented well. The design can be better explained, the year of the study can be mentioned, treatment names or plantation years can be better presented in terms of chronological sequences which will make it easier to present and understand the key findings of the study. For example, it would be much appreciated if the authors could replace the names of different years i.e. 1968, 1973, 1985, 1996 and 2002 with the age of the plantation i.e. 50 years, 40 years, 30 etc. Such details in chronosequence like studies are much clearer than the present version. It will reduce the ambiguity and will increase the clarity in presentation and understanding. Take a reference year for comparison, no need to compared each and everything, keeping in mind the limitations of the publications.
4. The Statistical analysis section can be a bit elaborated. Path Analysis or SEM or multivariate analysis can be included for better presenting the data. At present it is so simplistic.
5. Results section can be concise and better presented by highlighting the key findings of the study and reducing the presentation of excessive percentage change. A reference year can be selected and all the other values can be calculated with respect to that value. It will make the comparison much better and easier to understand.
6. The discussion and conclusion sections can also be improved.

See the attached pdf file with detailed and more specific comments. The manuscript needs substantial changes in the presentation. After incorporating the changes suggested, it can be reconsidered further publication. Authors are advised to respond to each query raised by the reviewer in detail in the response to reviewer file for clarity.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

There are several sentences which need to be rephrased for more clarity. Authors are advised to rephrase the manuscript and recheck for the grammatical errors. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I think it's ok for publication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has been revised substantially in light of the comments given earlier. However, the revised version is still not appropriate for recommending it for publication in its current form. There are several corrections in the manuscript which need to be addressed appropriately before proceeding further. For example,

1. The no. of years of study presented (earlier suggested were Abstract version) are not aligning with the actual years presented. Kindly pay attention to this. What was the reference year for considering these study years? Was it 2022 or 2015? For example, if 2022 is the reference year, then 2002 would be 20 years old plantation, 1996 would be ~25 years old plantation, 1985 would be ~35 years old plantation, 1973 would be ~45 years old plantation, and 1968 would be around ~50 years old plantation. Kindly check it and correct it throughout the manuscript accordingly as per the actual years, not the Abstract years suggested (50 to 10 years). See Table 1 and other instances (LN 146, and many others).
2. Was the study sampling was conducted in 2015? Why this much old data is presented in this study? Why not the sampling was done recently?
3. In Figure 1, authors need to present the coordinates and scale bar for more clarity.
4. Also correct the number of years in Figure 2. Figure 2 can be more clearly presented.
5. Authors are suggested to present the Statistical package names in italic fonts throughout the manuscript. For example, LN 191 - lavaan, LN - 211, 213 and many such instances.
6. LN - 194: STC? Soil Total Carbon? elaborate at first mention.
7. LN - 194-195: present in a sentence form.
8. Figs. 3-5 and related figures: Kindly improve the figure quality. The Post-hoc analysis results presented in red or not clearly visible. Kindly check the units superscript and subscript presentation. Kindly check the presentation of all the figures for clarity. The figures are not clear and difficult to follow.
9. Fig. 3 caption. Kindly check the whole manuscript for superscript and subscript related corrections.
10. Kindly delete ± Std. Err from all such figures' captions.
11. LN - 299-300: So what was the reference year of comparison? 10-years plantation of the date of sampling?
12. Fig. 10: Is it SEM or correlation analysis result?
13. Fig. 11: The figure caption can be better presented. Even the Figure or path diagram can be better presented.
14. LN 394: This is your finding, then why the reference support is given here?
    If it is discussed in light of the literature, then only reference support is needed. Or are the findings corroborate with the mentioned references / studies?
15. LN - 440-443: The sentence can be rephrased for clarity.
16. LN - 446: Kindly follow consistent abbreviation in the whole manuscript.
17. LN - 502: But the depth taken in this study was 0-50 cm only? then why 30-80 cm depth is mentioned here?

Authors need to really work on the manuscript, particularly results part and rephrasing of discussion part for more clarity. Figures also can be presented in a better way.

Comments on the Quality of English Language

The manuscript needs to be corrected for language as there are many sentences which are not clear. The results are also not presented well.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf