Distribution and Factors Influencing Organic Carbon Stock in Mountain Soils in Babia Góra National Park, Poland

Round 1

Reviewer 1 Report

In this straightforward paper the authors report the results of soil carbon sampling across diverse landforms within a mountainous region of south western Poland.  Soils were sampled by horizon to a depth of 1 m in 59 plots in Babiogorski National Park and analyzed for organic carbon, texture, pH, base cations, and bulk density including % stones.  Each plot was further characterized according to its soil type, Topographic Position Index and vegetation cover.  Data were analyzed with a combination of general linear modeling and principle components analysis.  Methods are standard, well described and well executed.  Results were clearly presented and showed that soils in this region conform to general expectations, with most organic carbon occurring in the upper 20 cm, histosols having the highest organic carbon content, and nitrogen fixing vegetation enhancing soil carbon accumulation.  The authors do a good job of putting their results within the broader context of European soil carbon distribution and its environmental drivers.  While largely confirmatory, this paper nonetheless adds valuable quantitative, and robust, data to the soil carbon literature and should be of interest to a diverse group of readers.

I have no substantive concerns.  The paper should be edited carefully for English language and typographical errors, e.g., lines 47, 52, & 166.

Author Response

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Reviewer 2 Report

The contribution deals with soil organic carbon stock in Babiogorski National Park, Poland. I consider the current topic as much demanded, realized work brings interesting new insights about the Carbon in the soils of the mountain forests. According to me, however, is to be done in the whole text major changes, supplements and adjustments.

Comments:

1.  In abstracts (Row 7), it was estimated more than 47% of carbon accumulation that is above 20 cm depth. Such results, however, are no supported with scientific analysis in this work. Analysis needs to be added to text. The topographical factors influence soil conditions and vegetation which results in a diversity of carbon accumulation in mountain soils of the BNP. What nearer topographical factors? Add and adjust text.

2.  Histosols show very high amount of organic carbon (> 550 tC.ha-1). This result is for me marvelous. It is really? Maybe continual area of histosols is not very large and results from one little sample cannot calculate to hectare. I see by soils very high variability, this fact limits generalizations. How variability of carbon content was determined by histosols? Add results.

3.   To keywords was chosen “altitude”. Why just altitude? Your results of soil organic carbon stock show no dependence from altitude. Check all keywords and choose that are more appropriate!

4.  R31: – the amount and quality of soil organic matter depends of the forest land management. How? Management increases or decreases? Add appropriate text.

5.   R44:49 35´18´´ N 19◦ 32´ 55´´. It is a center of the National Park or which point of monitored area? I recommend leaving only the approximate coordinates 49 ° 35 ' and 44 ° 19 ´ or put the margin boundaries of Babia Gora National Park from – to (north, east, south and west).

6.   R47: over 1400 mm [?] What is it? Maybe add source of information’s.

7. R48: growing season in the lowest portion of the Babia Góra National Park is 202 days. In addition, in the central or upper area? Too, add information’s and append source!

8.  Fig 1: Remake and adjust. I recommend map of Poland to enlarge, highlight the republic boundaries. I think, area of the BNP be enough just in once map (not two), in which highlight monitored area. Why you not watched  “white areas” in central part? How large areas you monitored? Add value (hectare).

9. Soil sampling. Instead of test areas I recommend to use research plots or inventory plots. What was the size of each soil sample? Specify weight or volume! How you differentiate the horizons – visually or by constant depths? If not constant, what should be the minimum, average, and maximum depth of 59 samples? What were the depths of all soil samples? What depth represented samples and, therefore, the results in the monitored area? I recommend to add a table or histograms with statistic of soil depths. Too classification of forest stand is very simplified. All 59 IP you classify explicitly only into 4 classes? I think that in the Mixed forests class should be allowed all plots, whose haven´t Spruce, Beech or Alder over 80%. Is it so? For example: if spruce had share 70% and beech 0%, what is result? Explain and adjust text.

10. Statistical analysis: Add in the methodology, the used form of results. It is everywhere reported the average ± standard deviation or standard error? What is the "T" in the equation (2)? What is the fraction 0-1? It does not reflect the "stoniness"? Explain in details.

11.  Laboratory analysis. To align the unit, for example: tha-1, g kg-1, Mg* m3... You use Gram or Kilogram or Megagram or Tonne? Same in table 1 and whole results.

12. Results. Table 1 is in my opinion OK. But due to the high variability (somewhere to incredible), however, I recommend a supplement in addition to the average and minimum or maximum; the table or histogram with more classes would be appropriate. For example: the pH of the class 3-4, 4-5, 5-6, 6-7, > 7 indicate frequency (number) or proportion (share) of  soil sample (inventory plots). As well you can add this too for other characteristics – SOC, N, C/N, Na, Mg, Ca, K,. To supplement the results of pH KCL, or is it omitted in the methodology (R82)?

13. The results indicated Stonines. (Fig 2). How was Stonines determined? In Laboratory from soil samples, or only visual estimate? Add in detail in the methodology.

14. In the results, you must in charts necessary to mention too the number of cases (share %). I suppose that the Fig 2 always has 59 cases (soil samples). However, figure 3 reflects the average data of the entire territory? Specify this. How much was a proportion of Alder, Spruce, Mixed and Beech stands in figure 4? Too in the Figure 5 and 6? In addition to the average, would fit well as histograms. You must in the results highlight the fact, which the relationship between T-SOC and altitude has failed in detail!

15. Fig 7 left is not good visible. Change this picture. Just as in Fig 8 supplement comparison of T-SOC depending on topography.

16. Conclusion (R243). SOC stock after your results is not depended from altitude (fig 7). Alder had a greater capacity to incorporate organic carbon in the soil. In average, maybe, but the variability is very large (fig. 4). Can you such a generalization? Adjust text.

Author Response

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Reviewer 3 Report

The authors have collected a valuable data set. Yet, the evaluation of the data is not strong enough. I recommend rejecting the paper and fully technically overhauling it.

Presently, the paper reads like a student's project. Many analyses are done, but the interpretation of the results is weak.

Different parts of the text may have been written by different authors. There are style changes.

Specific comments:

The idea that alder leads to a strong accumulation of soil carbon is not well supported. In order to do that alder needs to have a lot of litterfall and / or poorly decomposable litter and / or needs to inhabit a particular site for a long time (centuries) in order to be responsible for a marked accumulation of soil organic matter.

Introduction

In the first sentence the authors are talking of carbon accumulation. I think the term 'carbon stock' would be better (as used in the title of the two references).

lines 24-25: the sentence is overly complicated.

the ref[11] on line 27 is unexpected. what kind of info has been found in the encyclopedia?

the statement of lines 32-33 needs strong references. Managed forests and forests under protection status may equally have similar soil C stocks.

Material and methods

l 53 typo hyeperdystric

l. 58 I suggest ... the NP is covered with ..

chapt 2.2

the used humus classification Oh, ...OM should be cited.

The soil sampling is not clear:

there is a statement that the upper 2 mineral horizons have been sampled

in figures 2.. the soil profile is divided in sections

and some results refer to soil C stocks to a depth of 1 m.

A clarification is required.

Elevational zones

in section 2.1 a different classification is given as in section 2.2.

chapter 2.4

the first two sentences belong to chpt 2.2.

The description of the used parameters needs to be formulated better.

Figure 4 shows that soil C stocks are highest under alder. Possible conclusions are that alders grow preferentially on C rich soils. the used conclusion that alder creates C rich conditions is not supported.

Comparing C stocks of different forest types is trickery. The differences can be caused by differences in rock contents. Therefore, it is required to also compare C contents (C mg/g). (this comment applies for several graphs).

The statement on line 158 ff may be inapplicable. The 'position along the slope', in this case base of slope, may fully explain the differences.

In fig 5 a typo: fuvisols; attn: this txt has been copied and pasted several times

line 166 typo sotck.

The Discussion is very much independent of the studied sites and the collected data. The text is rather a literature review. It is recommended to put the results in perspective to the studied region.

The statements from line 225 to the end are potentially mis-interpretations.

l. 195: the term 'efficiency of ecosystems' is not clear.

References

Ref 10 has an unexpectedly abbreviated second author.

Author Response

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Round 2

Reviewer 2 Report

The authors have made a number of changes according to the reviewers comments, but unfortunately, it seems to me that they were not very consistent, respectively, a number of changes are insufficient.

I think that the "Forest ecosystem" is not the most appropriate keywords. I recommend instead abbreviation to indicate the full name of the SOC.

Modified was the text to the effect of forest management (R34-35). But what are the main differences between managed and unmanaged forests? Supported by the relevant citations? In my opinion, are managed forests also very significant for carbon sequestration! Even more significant as unmanaged. The most fast-growing plantations aged 20-40 years sequestrated most carbon in tree biomass per hectare and year. The text is necessary to significantly modify and complete!

Figure 1 was changed, but the text is not readable in the published version (small letter size), and would be entirely lost significance. Edit to better visible to the readers. The text was added: The share of stones in particular genetic horizons was determined as a percentage. Even duplicate (R84-85 and R95)! However, it does not explain how to investigate the share! Amend the method of calculating!

R100-BD is certainly does not reflect in g. m3 but in g. cm3! Rather, I would recommend to adjust the “t” on the “Mg”. 

What is the fraction 0-1 (R101)? Explain! 

What are Profile sections in Fig 2 and Fig 3? How were to estimate? State the reason, explain, supplement it! 

Profile 6 in Fig 2 does not have an standard deviation intervals, append. Even in the methodology. I recommend append graph express dependency the carbon content from the soil depth. Either scatter graph, or histogram, both optimally.

In Chapter 3.2 you complement the Carbon content after A, B and C horizon too the total Carbon content. Just add their shares in A, B and C horizon, in order to have complete data on the percentage of carbon in the horizons. What were the depths of horizons, if did not use the same sampling depth? Add-on.

In Fig 3 standard deviation intervals are not referred. Add-on.

Fig 7. Correct data on the Y axis (-5 to 35 t ha-1 is nonsense). Axis X needs to start at 0.

R196 – in this study was 47% in not estimated. Where? Add in the results! Compare Row 197 with Figure 3. What are the surface horizons?

Description of the X axis in Fig 10 is absolutely unreadable. Overall, I don't find significant chart, I recommend delete.

Chapter Conclusion I think is weak, a little concise, do not select the main results and conclusions, I'd recommend it to all the make over.

Author Response

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Reviewer 3 Report

The manuscript has been greatly improved. My congratulations to the authors. I recomment its publication.

Author Response

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