Stocks and Stoichiometry of Soil Organic Carbon, Total Nitrogen, and Total Phosphorus after Vegetation Restoration in the Loess Hilly Region, China
Round 1
Reviewer 1 Report
The MS “Stocks and stoichiometry of soil organic carbon, total nitrogen, and total phosphors after vegetation restoration in the Loess Hilly Region, China” by Xu et al. deals with the effects induced by vegetation restoration in a Loess Region of China on the soil nutrient properties. Different vegetation types, vegetation ages and soil depth on the content of organic carbon, total nitrogen and phosphorus were considered. The study presents a good experimental design and a good statistic elaboration. The data are well presented. However, the manuscript reveals some shortcomings that must be resolved before it can be published.
General and specific comments
The MS has several typos and needs to be checked with attention.
Discussion
The authors should also remember that the restoration (and/or change) of vegetation in addition to having an effect on the amount of the organic carbon and nitrogen of the soil might have repercussions on the process of mineralization/humification of the soil organic matter (Pizzeghello et al., Forests 2017, 8, 197; De Feudis et al., Forests 2017, 8(6), 213). The pool of humic substances present in the soil is, in fact, important for the ecosystem as it strongly contributes to fertility but also because durable carbon that lends itself to being stored (Pizzeghello et al., Forests 2017, 8, 197).
Conclusions
Conclusions are badly written and need to answer (at least in part) the questions made by the authors in the aim of the paper (lines 81-91).
Abstract
In light of the aforementioned changes, the abstract will also be modified.
Other minor comments have been written directly into the text.
Author Response
Responses to Reviewer 1 Comments
Point 1: The MS has several typos and needs to be checked with attention.
Reply: Thank you very much. We have carefully checked and modified our manuscript to ensure the correctness of all words and grammars. At the same time, the paper has been professionally edited for English language by a service.
Point 2: Discussion
The authors should also remember that the restoration (and/or change) of vegetation in addition to having an effect on the amount of the organic carbon and nitrogen of the soil might have repercussions on the process of mineralization/humification of the soil organic matter (Pizzeghello et al., Forests 2017, 8, 197; De Feudis et al., Forests 2017, 8(6), 213). The pool of humic substances present in the soil is, in fact, important for the ecosystem as it strongly contributes to fertility but also because durable carbon that lends itself to being stored (Pizzeghello et al., Forests 2017, 8, 197).
Reply: I am very grateful for the reviewer's comments which are very helpful for my paper. We have been revised our discussion according to the reviewer's comments. And the literature suggested by the reviewer to quote had been referenced in the paper. Thanks again to the reviewer for these good comments.
Point 3: Conclusions
Conclusions are badly written and need to answer (at least in part) the questions made by the authors in the aim of the paper (lines 81-91).
Reply: The conclusion has been revised into “We examined the changes in SOC, soil TN, and soil TP stocks and stoichiometry at depths of 0–100 cm following vegetation restoration in the Loess Hilly Region. Our results revealed that the SOC stocks appeared to increase and reach stable levels; the soil TN stocks first increased and then decreased with restoration age but it is difficult for them to reach the levels seen in natural grassland or natural forest in the Loess Hilly Region without appropriate management; the soil TP stocks with changes were poor with restoration age; the C:N, C:P, and N:P ratios gradually increased with restoration age. At the same time, the SOC, soil TN, and soil TP stocks, and C:N, C:P, and N:P ratios decreased with soil depth. Additionally, forestland had the highest sequestration rate of SOC and TN at 0-10 cm soil depth. The results of this study provide data for the assessment of the long-term SOC, soil TN, and soil TP stocks and stoichiometry after vegetation restoration under different restoration types in the Loess Hilly Region.” according to the reviewer’s comments.
Point 4: Abstract
In light of the aforementioned changes, the abstract will also be modified.
Reply: The abstract has been revised according to the reviewer’s comments.
Author Response File: 
Author Response.doc
Reviewer 2 Report
Comments on Xu, H., et al.
The paper is easy to read and in general the English is up to par. However, I recommend the authors not to use the words positive and negative, it is confusing. In general the figures, in particular Fig. 2, Fig. 4, and Fig. 6, are too small to be read. A possible explanation for the observed is storage of N and P in the vegetation, I would like the authors to elaborate. Parts of the Results and Discussion parts are difficult to read with all the abbreviations’, the passages would benefit from introduction of clearer paragraphs.
Minor comments
Line 38, change ‘earth’ to ‘soil’
Line 108, write vegetation type before each abbreviation
Line 126, It is not clear how the estimates were performed,
Figure 2 caption move FL after ‘and’
Author Response
Responses to Reviewer 2 Comments
Point 1: The paper is easy to read and in general the English is up to par. However, I recommend the authors not to use the words positive and negative, it is confusing. In general the figures, in particular Fig. 2, Fig. 4, and Fig. 6, are too small to be read. A possible explanation for the observed is storage of N and P in the vegetation, I would like the authors to elaborate. Parts of the Results and Discussion parts are difficult to read with all the abbreviations’, the passages would benefit from introduction of clearer paragraphs.
Reply: Thanks for your kind suggestions. All the figures in our manuscript have been redrawn. In our study, we aim to examine changes of the stocks and stoichiometry of soil organic carbon (SOC), soil total nitrogen (TN), and soil total phosphorus (TP) after vegetation restoration with soil depth and restoration age in different restoration types on the Loess Plateau, rather than the plant nutrients characteristics. In order to exclude doubts from reviewers and readers, we have added relevant content in the Materials and Methods and also made clearer expression in the picture. All the abbreviations in Results and Discussion have been replaced by the full name.
Point 2: Line 38, change ‘earth’ to ‘soil’
Reply: The earth has been replaced by soil.
Point 3: Line 108, write vegetation type before each abbreviation
Reply: Thanks for your kind suggestions. All the abbreviations in our manuscript have been replaced by the full name.
Point 4: Line 126, It is not clear how the estimates were performed,
Reply: The “Calculation of SOC, soil TN and soil TP stocks” part has been revised into “The stocks of SOC and soil TN and soil TP from five soil depths of 0–10, 10–20, 20–30, 30–50, and 50–100 cm in different restoration types were selected in our study to research the carbon budget of the soil, and soil fertility issues after afforestation. The SOC, soil TN and soil TP stocks (Mg ha−1) were calculated as follows:
SOCi stock = SOCi × BDi × Di/10 (1)
Soil TNi stock = soil TNi × BDi × Di/10 (2)
Soil TPi stock = soil TPi × BDi × Di/10 (3)
SOCi is soil organic carbon content of the ith layer of soil (g kg−1), soil TNi is soil total N content of the ith layer of soil (g kg−1), soil TPi is soil total P content of the ith layer of soil (g kg−1), BDi is soil bulk density of the ith layer of soil (g cm−3), and Di is the soil depth of the ith layer of soil (cm).”
Point 5: Figure 2 caption move FL after ‘and’
Reply: The caption has been revised into “Changes in stocks of soil organic carbon (SOC), soil total nitrogen (TN), and soil total phosphorus (TP) with restoration age. Note: Values are mean ± standard error.”
