Dynamics of Leaf- and Root-Specific Biomarkers during 1-Year of Litter Decomposition
Rienk Smittenberg
Round 1
Reviewer 1 Report
Altmann et al present a useful study to test the assumed specificity of certain lipids, upon base hydrolysis, for root vs leaf material. They found that there is, in fact, a low specificity at best. The study was set up appriopately. However there are a number of unclarities in the text that need to be looked at. Also, the English used is clearly from a German-speaking author(s), and could use one more round of improvement. I have given my comments on the annotated pdf, including some spelling/grammar mistakes.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
Thank you very much for reading and considering improvements for our manuscript.
Your extensive and sharp comments were certainly very helpful for further enhancing the quality of our text.
We corrected and improved the points mentioned in your review.
See below our answers:
line 29: suggestS : remove S
corrected
line 53: over- or underestimation
corrected
61: Norway spruce.
The use of species names was checked and corrected throughout the whole manuscript
line 65: reachED reaching
corrected
line 67: in SOME cases, in OTHER cases...
corrected
line 113: mL......should be : ml
corrected
line 120: ...of root- and leaf-derived...
corrected
line 163: xt/x0= e ( -kt) (...) should be higher!
The formular was changed to xt/x0 = e-kt
fig 1: All tree species names should be checked: European ash, European beech and further. Same applies for Table 1
corrected
line 199: ..., for coniferous speciES
corrected
line 234 ....after 6 months , for Oak....
corrected
line 284. suberized.........
corrected
line 292: " needle material of Oak" ??????
corrected
line 297: ...in our selection..OF......leaf indicator molecules.
corrected
line 298: .......GEOSCIENCES.......
corrected
line 308: who observed (skip comma).........
corrected
line 324: ...two monthS of litter....
corrected
line 335: ...cutin anD suberin.....
corrected
line 342: .....PROVED to be ....
corrected
line 387 ....archAelogy.....
corrected
line 451: 2008 should be in bold!
corrected
line 500: Comparative....
The sentence was corrected to: „A comparative study…“
Reviewer 1
line 126
We appriciate the remark of reviewer 1. The fraction of free extractable lipid is dominated by n-alcanes, aliphatic alcohols and carboxylic acids. These compounds are not specific enough to distinguish between free extractable lipids and free lipids generated by cleavage o fester bonds. We could not detect hydroxy-fatty acids in the extracts in previous studies, that’s why we discarded the results.
line 144
we used this standard method, which was applied in various publications. We will conduct a trial in the future and compare the two timespans. To our knowledge it did not harm the samples to stay in the reaction vessel for 1 hour.
Pyridin is not a considered in this method
line 157
we added literature references for mass spectral interpretation
line 163
the formula was corrected
line 164
the litter material was dried and brittle. Therefore, we aimed at weights between 9,97 and 10,03 g. We tried not to destroy the structure of the incubation material more than necessary, to imitate natural conditions as close as possible. Therefore, maximal homogenization of the samples was not our primary goal. Before CO2 measurements, the samples were water extracted. At the beginning and at the end of each water extraction, the samples were intensely stirred and homogenized.
line 170
the respicond apparatus was set to hourly measurements of the CO2 emission rate. These rates were used to calculate and characterize mass loss over time. The figure only has the function to characterize the state and intensity of litter degradation in our experiment at the sampling dates. With the objective to keep the article focused on biomarker degradation, but with reference to the characterization of the whole process of mass loss. The principal results achieved in our experiment would not be any different, if a second figure would be added.
line 184
Significant differences between the sampling dates were tested using the one-way analysis of variance (ANOVA) with Tukey’s honestly significant difference (HSD) post-hoc test. This was to our belief expressed in the method part. Hence this might be too short, we added some more information to chapter 2.4.
line 229
the misleading use of the word “amount” was corrected
line 244
- the units were corrected
- the presented concentrations are shown as amount of biomarker per amount of organic carbon. The amount of carbon in the sample is calculated with the CO2-loss-data.
- With this article, we want to test the suitability of established biomarker methods about making assumptions regarding the amount of leaf- or root-derived organic matter. This approach requires constant concentrations over time. Only constant concentrations or concentration changes with the same factor would allow linear calculations in combination with the soil carbon content. Increasing or decreasing biomarker concentration over time, would result in overestimation or underestimation of the remaining source material. The amount of biomarker over time, in our opinion, does not contain any information of interest for ecological or climatological questions.
Line 265
The proposed wording was adopted
Line 278
The intended improvement of the reviewer was not to clear to us. Therefore, we decided to leave the wording as it was.
Line 297
corrected
Line 298
corrected
Line 313
Text was extended. Further information was added.
Line 338
Thank you for the very interesting remark, we will consider this fraction for future studies.
Reviewer 2 Report
The authors (Altmann et al.) have submitted a manuscript entitled " Dynamics of leaf and root specific biomarkers during 1-year of litter decomposition". The manuscript over a currently important topic and the subject meets well with the journal's scope. This is an interesting study, however, from my aspect, there are at least three significant flaws. Firstly, the method. The litter decomposition digresses from the environment (climate, soil animals, et al.) is incomplete. In this study, the authors use quartz sand instead of soil to simulate the environment decomposition, how can leaf and root degradation without soil organisms? Only leaching may happen during the incubation. Secondly, the major technical errors in writing. In my opinion the manuscript and thus the referenced study on the whole contain major technical errors. The manuscript fails to fulfil basic standards regarding the scientific consensus. e.g., the authors must define abbreviations when they first appear in the main body of the article. Thirdly, the introduction. I was missed in the section of Introduction, since there are too many paragraphs. Reading the introduction, I feel that the authors are not clear about what they want to achieve with this study and have expressed my concerns below. Moreover, only one-year incubation experiment, how can the author improve the understanding of the long-term decomposition of tree root and leaf derived ester-bound lipids?
Results
From my aspect, I don’t think the authors calculated the k value correctly, since the value are only around 0.001.
Author Response
Dear Reviewer,
Thank you for having read our manuscript and giving such useful advises.
We checked for abbreviations and added all necessary definitions.
But we do not share the view, that “the k-values are only around 0.001”, as we clearly showed, that k values range from 0,0008 to 0,0023. k-values were grouped after statistical analysis in two clusters, labeled as cluster a and cluster b. Within each cluster the results can be interpreted as close to similar, but between two clusters they are significantly distinct.
Best regards
Reviewer 3 Report
The paper conducted an incubation experiment with roots and leaves of six different temperate European tree species under standardized laboratory conditions for 1 years. The valuable focus is to select on biomarkers for the distinction of leaf and root material. This is important for explore the behavior of litters and toots for soil organic inputs. However, Some important information such as the description of how to add the mixed quartz sand and litters or roots were not provided in the paper. And the method of 27-different ester-bound lipids should be clear introduced in the method section. And how to use those lipid to judge which bounds can be used the biomarkers for leaves and roots should be clearly introduce in the Incubation experiment. except those flaws, it is a good paper can provide one method to select the best biomarkers for leaves and roots.
Author Response
Dear Reviewer,
Thank you very much for reading and considering improvements for our manuscript.
Your comments were helpful for further bettering of our text.
We corrected and improved the points mentioned in your review.
We are confident, that we gave all relevant information to make it possible to reproduce our experiment. We are sorry, if we could not give all details of our laboratory method, but we are very open to scientific exchange of ideas and discussions. Please feel free to get in contact with us!
Best regards
