Soil organic matter interactions along the elevation gradient of the James Ross Island (Antarctica)

This manuscript examines SOM interactions on James Ross Island, Antarctica, focusing on SOC, GRSP, P, and microbial activities across altitudes. It provides insightful data on how extreme polar conditions affect soil C dynamics, contributing to our understanding of carbon sequestration processes in polar ecosystems. Despite its promising contributions, the manuscript would benefit from further refinement in areas such as methodological descriptions, statistical analyses, and discussion to enhance overall clarity and impact.

The introduction of this manuscript could benefit from a clearer connection between global soil C significance and the specific contexts of Antarctic soils. Currently, the introductory section opens with a sentence that seems unrelated to the central theme of the research (L39), which might distract from the focal point of the study. By consolidating the first and second paragraphs into a more cohesive unit, the narrative could be strengthened, thus providing a clearer justification for the research focus.

Materials and Methods:

1. Please verify and standardize subscript and superscript usage throughout this section to maintain consistency.
2. It is essential to specify the number of soil samples collected at each site. Detailing this information will strengthen the study's replicability and statistical validation.
3. Section 2.3 lacks details on soil C and N testing methodologies.
4. The absence of ANOVA or similar statistical tests to analyze data variability among elevation gradients and treatments should be addressed.
5. The inclusion of delta pH in the statistical analysis needs reevaluation.
6. I have not seen papers using the difference between pH_H2O and pH_KCl as an indicator of soil buffering capacity. I am not saying that’s incorrect, but an explanatory experiment or references justifying this approach would be beneficial.
7. Please use built-in functions for equations like this (Δ[H+] = 10^(-pHKCl)–10^(-pHwater)) to enhance readability.

Results:

1. Inclusion of statistical significance and standard error details in Tables 2-4 is necessary to substantiate the research findings.
2. For Table 2:
   1. the symbols (***, **, *) generally used to denote statistical significance. Please consider used other symbols to avoid any potential confusion;
   2. The term "coarse fractions" needs to be specified—do these refer to gravels or sands?
   3. M&M does not address the presence of total N explicitly. If total N is measured, does and how SOC is measured? In addition, I don’t really understand why SOC is in Table 3 instead of Table 2. I think Table 2 and some parts of Table 3 should be combined or represent their data through a figure that illustrates changes across elevation gradients.
   4. The rationale for displaying both ∆pH and ∆[H+] is unclear. The expression 10^(-5.80) may not be readily interpretable by all readers.
3. Table 3: Please specify what "N" stands for—is it referring to soil total N?
4. Figures 3 and 4: captions should be positioned underneath the figures.

Discussion:

1. L271-273 redundantly states the last part of Introduction.
2. L286: I think another important thing that could be mentioned is P has low mobility. Apatite has calcium. If the decrease in weathering intensity of apatite is indeed the cause behind the correlation observed between Melich-3-P and altitude, then why is it that we do not observe a similar correlation between altitude and available Ca?
3. While the manuscript provides data on total N, the discussion on N cycling is notably brief. Given the unique environmental conditions of Antarctica, incorporating a detailed analysis of N transformations could significantly enhance the understanding of nutrient dynamics in polar ecosystems. The effects of Antarctic conditions, such as low SOM concentrations and C/N inputs, along with the ecological influences of freeze-thaw cycles and seabird activities, warrant deeper exploration.
4. Something about Table 3:
   1. I didn’t find any linear curve in Table 3 (L300).
   2. The most important data in this study were in Tables 2-4 and Figure 2. I do think the authors have spaces to provide more in-depth relationship of measured parameters, like presenting the linear curve mentioned in L300.
   3. By just looking at numerical values in Table 3, I felt the deviation of the conversion factor would be large. The authors should also provide R² and p-value of the regression lines.
   4. Another question is, is C in GRSP not part of SOC? The authors didn’t provide information about C (and SOM) analysis in M&Ms, but I think GRSP is part of SOC for dry combustion analysis. If C analysis approach in this study is not the most common approach, does it make sense to compare the conversion factor to studies with different SOC/SOM measurement method?
5. I am not sure how to interpret Fig 4 to get this statement “OM decomposition was linked with microbial activity”.

Dear colleagues, 



I had a privilige to review a manuscript titled "Soil organic matter interactions along the elevation gradient of the James Ross Island (Antarctica)", which presents important study of soil organic matter in Maritime Antarctica region.



Despite, soil organic matter is quite studied topic in soil science, still only few research exists dedicated to complex investigationn of soil organic matter in Antarctic soils. It is also worth to note that the carbon stocks in Antarctica are  underestimated compared to the Arctic due to the lack of data on many parts of this continent due to the high occurrence of rocky soils, as well as the high variability of the carbon content in

fine-earth material. This also highlight the importance of the abovementioned submission, since every single work providing assessment of carbon content in Antarctic soils is vital for delineating the stocks along the sixth continent as well as its changes along the latitudinal, longitudinal gradients and different landscapes.  For example, current estimates report the stocks of organic carbon in Antarctic soil are 0.5 kg m2 100 in polar deserts, about 1.0 kg m2 in barrens, up to 3-5 kg m2 in subantarctic tundra and up to 30 kg m2 in localities under penguin nesting sites in Maritime Antarctica.



I believe that this article is worth publishing in the journal. The experimental design of this paper is clear and understandable, all the goals highlights the importance of provided results. However, some minor revision is needed. My comments are below:

1. Could you please try to combine Results and Discussion into one chapter, so it will be easier for readers to follow the discussion after the respective results (which are many and of great importance for soil and permafrost communitym and not only for them!)



2. Please think about performing (if possible) some detailed SOM molecular study, i.e. 13C-NMR or FTIR, to show the difference in molecular composition in soil organic matter along the studied environmental gradient. This is also imprtant for assessment of stability of organic matter and for assessment of current and potential stocks of organic carbon and related to the degree of humification in Antarctic soils. 

3. Please try to expand the "Conclusions" part, since in the present form there are less conclusions than results provided in the manuscript (which are of course worth to be explained as Conclsuions of the presented work).



I would be pleased to review the revised manuscript and see it published in the journal in near future.