Evaluation of Forest Conversion Effects on Soil Erosion, Soil Organic Carbon and Total Nitrogen Based on 137Cs Tracer Technique
Round 1
Reviewer 1 Report
This manuscript presents a study designed to examine differences in SOC and nitrogen storage and loss following forest conversion from conifer/broad leaf (CBF) to apple (AF), chestnut (CF), or hawthorn (HF). Soil erosion rates were inferred using 137Cs analysis, and other soil characteristics were evaluated using standard methods. Given the widespread and ongoing conversion of natural forests into managed forests, and the potential effects of these forests on climate change and other ecosystem services, this study has the potential to be of broad interest. The results generally are straightforward, and the discussion generally is appropriate for the results, so I think the manuscript is acceptable with fairly substantial changes - I do have a suite of concerns, noted below, about certain aspects of the manuscript that may detract from its usefulness for forest managers and the likelihood that it might be cited by other authors.
Comments:
The text needs to be carefully rewritten for typos, grammar and word choice. There are several errors (e.g., ‘planet’ instead of ‘plant’) that fundamentally alter what is trying to be conveyed. Also, some words and phrases (e.g., forest transformation and forest conversion) are used interchangeably, though they don’t necessarily mean the same thing. For example, forest conversion and forest transformation potentially could refer to two very different outcomes, such as forest conversion to managed stands and forest transformation into housing tracts. In this example, because forest conversion is defined in the text, while forest transformation is not, I would only use forest conversion.
Because only one forest of each type was studied, the Discussion should reflect this limitation on extending the results to other forests. For example, the benefits of chestnut forests may not be realised in other areas, where environmental conditions may be different.
Along those lines, the confounding effects of litter depth and forest management need to be addressed more clearly. As the authors note, litter fall played a key role in differences among the forests. But the study didn’t address the degree to which litter fall may differ among forests of the same type. (For example, this chestnut forest may have more litter fall than other chestnut forests, due to site-specific characteristics not related to the stand management.) As a result, the potential benefits of chestnut forests observed in this study may rely more on the depth of litter at the study sites than on management for chestnut trees. This issue is partially addressed in Section 4.1 (l. 264-269), but should be addressed in more detail. For example, one implication of these results is that forests should be managed in multiple ways to maintain litter, not just in the types of trees selected. This study has the potential to be of interest to a fairly wide audience involved in forestry and forest management, but the management recommendations are more likely to be adopted, and the paper more likely to be cited, if the results of the study are placed in the proper context.
The statistical analyses appear to be appropriate and correctly interpreted, with a couple of suggestions. The Results (l. 182-183) indicate Cs activity differed between 0-10 and 10-20 cm in all treatments except AF, but there don’t appear to be any statistical analyses that support this statement. Also, the statement (l. 210-211) that the SOC and TN storage of the CF soils was greater than those of the other three forest types does not appear to be correct - I think CBF was meant to be listed here. I also have a couple of other questions and comments. First, the number of significant digits after the decimal should be consistent (e.g., Table 2), and, for the % data, should either be only one or no digits after the decimal (e.g., in Table 2, the % data shouldn’t have any digits past the decimal). Also, which version of R was used for the statistical analyses? Data were tested for normality and homogeneity of variances, but it’s not reported whether the data might the assumptions.
Author Response
Response to reviewer 1 Dear Editor and Reviewers: We greatly appreciate your favorite considerations and reviewers’ careful review of our revised manuscript. We have made correction according to the reviewer’s comments. I am submitting the revised one for your consideration as well as detailed responses to the reviewer comments. The manuscripts with no track changes and with track changes were both uploaded. We do feel these comments help improving the quality of the paper. I hope this revision can make the paper more acceptable. The revisions were addressed point by point below. Sincerely Xi Zhu. Reviewer 1 This manuscript presents a study designed to examine differences in SOC and nitrogen storage and loss following forest conversion from conifer/broad leaf (CBF) to apple (AF), chestnut (CF), or hawthorn (HF). Soil erosion rates were inferred using 137Cs analysis, and other soil characteristics were evaluated using standard methods. Given the widespread and ongoing conversion of natural forests into managed forests, and the potential effects of these forests on climate change and other ecosystem services, this study has the potential to be of broad interest. The results generally are straightforward, and the discussion generally is appropriate for the results, so I think the manuscript is acceptable with fairly substantial changes - I do have a suite of concerns, noted below, about certain aspects of the manuscript that may detract from its usefulness for forest managers and the likelihood that it might be cited by other authors. reviewer1: Comments: Point 1: There are several errors (e.g., ‘planet’ instead of ‘plant’) that fundamentally alter what is trying to be conveyed. A: Sorry It should be “plant distribution”. I misspelled. Point 2: Some words and phrases (e.g., forest transformation and forest conversion) are used interchangeably, though they don’t necessarily mean the same thing. For example, forest conversion and forest transformation potentially could refer to two very different outcomes, such as forest conversion to managed stands and forest transformation into housing tracts. In this example, because forest conversion is defined in the text, while forest transformation is not, I would only use forest conversion. A: After reading your explanation of the two words, I found my choice of words inaccurate. I have corrected it to “forest conversion”. Thank you for your correction. Point 3: Because only one forest of each type was studied, the Discussion should reflect this limitation on extending the results to other forests. For example, the benefits of chestnut forests may not be realised in other areas, where environmental conditions may be different. A: Your suggestion has been supplemented in the discussion section 4.1 Point 4: Along those lines, the confounding effects of litter depth and forest management need to be addressed more clearly. As the authors note, litter fall played a key role in differences among the forests. But the study didn’t address the degree to which litter fall may differ among forests of the same type. (For example, this chestnut forest may have more litter fall than other chestnut forests, due to site-specific characteristics not related to the stand management.) As a result, the potential benefits of chestnut forests observed in this study may rely more on the depth of litter at the study sites than on management for chestnut trees. This issue is partially addressed in Section 4.1 (l. 264-269), but should be addressed in more detail. For example, one implication of these results is that forests should be managed in multiple ways to maintain litter, not just in the types of trees selected. This study has the potential to be of interest to a fairly wide audience involved in forestry and forest management, but the management recommendations are more likely to be adopted, and the paper more likely to be cited, if the results of the study are placed in the proper context. A: Your opinions are invaluable to my thesis. According to your opinion, the discussion part 4.1 has been revised. Point 5: The Results (l. 182-183) indicate Cs activity differed between 0-10 and 10-20 cm in all treatments except AF, but there don’t appear to be any statistical analyses that support this statement. A: As can be seen from the histogram, the specific activity of 137Cs at the 0-10 cm soil depth was greater than that at the 10-20 cm soil depth in all land use types except AF. If this conclusion cannot be clearly seen on the graph, I can delete this one. Point 6: The statement (l. 210-211) that the SOC and TN storage of the CF soils was greater than those of the other three forest types does not appear to be correct - I think CBF was meant to be listed here. A: This conclusion has been revised according to your opinion. Point 7: I also have a couple of other questions and comments. First, the number of significant digits after the decimal should be consistent (e.g., Table 2), and, for the % data, should either be only one or no digits after the decimal (e.g., in Table 2, the % data shouldn’t have any digits past the decimal). A: The number of significant digits after the decimal should has been corrected to be consistent. the number of significant digits after the decimal point for the % data has been reduced to one. Point 8: Also, which version of R was used for the statistical analyses? Data were tested for normality and homogeneity of variances, but it’s not reported whether the data might the assumptions. A: The version of R was R 3.4.3. The data processing used in this paper did not test for normality and homogeneity of variances, which was added by me carelessly. It has been deleted from the article
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript brings interesting results on how forest conversion into economic forest increases soil erosion and affect soil properties (nutrients). There is a need for results which can be bring to the practice to protect the soil.
According to the instructions, the Methods section should be after Discussion (but it is jus a formality). The reference format do not correspond to the instructions.
The manuscript language is sufficient although sometimes a little difficult to read. Although I am not native English speaker, I have a feeling that the formulation and sentence formation should be improved. The specific comments follows.
Title: conversion in what
TN I am not sure if this abbreviation is so widely used so everyone knows what i tis (I would suggest to replace it for „total nitrogen“ or „nitrogen content“).
Evaluation of …. Based on…“ or …. Evaluated based on …
Key words:
Soil erosion and 137Cs are already in the title, please remove them
Abstract
The last sentence seems to me too strong conclusion. To conclude from the study on three species that the chestnut forest is the best is not appropriate. You may say that chestnut is the most convenient from the studied forest or, as you said in discussion, species which product litter are the most suitable to minimize soil erosion (or something like that)
Introduction
L37: delete the dot at the end after problems
L41. Insert space before [9-11]
L42: delete the comma at the end of the line
L44 and 45: abbreviations SOC and TN appear here for the first time in the text. Please explain.
L47. Insert space before [27]
L50: is “single” the right expression? Maybe uniform?
L51: I cannot see the purpose of this sentence in relation to the topic. Moreover, what did the authors mean with planet distribution?
L54: please, replace with: Such a change of …
L69: please specify what kind of conversion (into economic foret?)
L74: replace affect for affects
L76: what kind of distribution? Vertical?
L69-76: in research goals I miss the comparison of the studied forest types and search for the best forest type for conversion (which is one of the main issues in the conclusions)
2 Materials and Methods
Figure 1: please add “the” before study site
L103-115: I suggest to replace this paragraph into the section 2.1. Study sites. Are there any information about characteristics of the forest stands? (height, tree density)
L112: delete “old”
L245-246: I would suggest to connect these two sentences in to one ( …. because ….) as the second one is the explanation for the first one
2.3 Data processing: Please specify here what the individual analyses were used for. Then it do not have to be specified in results.
Table 1: Are those really information about plots? I think it is more about forest types. All abbreviations in the table should be explained (HF, CF, AF, CBF, LAI). There are some mean values – are that means from three replicates of forest types? It should be specified. It should be also specifies what the value after ± means. Please replace “Age” for “Forest age”
Results
L181: please add “to” after decreased
L182: please add” , respectively” after …and CF
L183: CBF had (instead of has)
L185: Put the dot after the layer and start new sentence to be easier to understand: “The specific activity of 137Cs in CH and CF was 1.28 and 1.06 times greater in 0-10 cm layer compared to 10-20 cm layer, respectively.
Table 2: Because the layer is the same for all forest types, I suggest to replace it to the title of the table: 137C loss in the depth of 10-20 cm for different forest types.
Figure 2: It should be stated whether those are the mean values and what the error bars indicate.
Figure 3: it seems to me that the
L218: this is the only place where you use the term “transition”. Did you mean conversion?
L222-223: It is not clear here what you compare, and please make the sentence shorter not repeating the same thing (The annual loss of topsoil nitrogen in HF, AF and CF was 1.51, 1.42 and 0.61 that of CBF, respectively.)
Figure 4: All abbreviation should be explained (AF, CF …). What do the boxes show? (mean, median, percentiles?)
Figure 5: In the caption, use please carbon and nitrogen relative losses (instead SOC and TN). Plus the same comment as in Figure 5.
Discussion
L264: according to table 1, the litter thickness is 1.1-1.3 mm. I do not thing it corresponds to ”much litter cover”
L265: I would be interested why there is no litter in AF and HF.
Figure 6. if this is the result of another study, it should be quoted in the figure caption (adopted from …)
Table 4: this output should be in the Results section
Conclusions
L318: I would suggest to replace “forest transformation” to “conversion of coniferous broad-leaved mixed forest into the economic forest” to be clear and correspond with the overall text.
I miss here the conclusion drawn in lines 267-269, which is kind of practical.
Comments for author File: Comments.docx
Author Response
Response to reviewer 2 Dear Editor and Reviewers: We greatly appreciate your favorite considerations and reviewers’ careful review of our revised manuscript. We have made correction according to the reviewer’s comments. I am submitting the revised one for your consideration as well as detailed responses to the reviewer comments. The manuscripts with no track changes and with track changes were both uploaded. We do feel these comments help improving the quality of the paper. I hope this revision can make the paper more acceptable. The revisions were addressed point by point below. Sincerely Xi Zhu. Reviewer2: The manuscript brings interesting results on how forest conversion into economic forest increases soil erosion and affect soil properties (nutrients). There is a need for results which can be bring to the practice to protect the soil. Comments: Point 1 Title: conversion in what TN I am not sure if this abbreviation is so widely used so everyone knows what i tis (I would suggest to replace it for „total nitrogen“ or „nitrogen content“). Evaluation of …. Based on…“ or …. Evaluated based on … A: The title has been changed to: Evaluation of Forest Conversion in Soil Erosion, SOC and Total Nitrogen Based on 137Cs Tracer Technology. Point 2 Key words: Soil erosion and 137Cs are already in the title, please remove them A:I have deleted them. Point 3 Abstract A: The last sentence seems to me too strong conclusion. To conclude from the study on three species that the chestnut forest is the best is not appropriate. You may say that chestnut is the most convenient from the studied forest or, as you said in discussion, species which product litter are the most suitable to minimize soil erosion (or something like that) I have changed the last sentence to “Therefore, we suggest that when developing economic forest, we should select species which can product litter to realize soil conservation as far as possible to reduce the risk of soil erosion.” Point 4 Introduction L37: delete the dot at the end after problems A: This error has been corrected. Point 5 L41. Insert space before [9-11] A: This error has been corrected. Point 6 L42: delete the comma at the end of the line A: This error has been corrected. Point 7 L44 and 45: abbreviations SOC and TN appear here for the first time in the text. Please explain. I have added the explanations. Point 8 L47. Insert space before [27] A: This error has been corrected. Point 9 L50: is “single” the right expression? Maybe uniform? A: Yes. ‘uniform’ more accrate. Point 10 L51: I cannot see the purpose of this sentence in relation to the topic. Moreover, what did the authors mean with planet distribution? A: It’s “plant distribution”. Sorry I misspelled. What I want to express is that forest conversion will affect all aspects of the whole ecosystem, and the impact of these interactions on forest soils should not be underestimated. Point 11 L54: please, replace with: Such a change of … A: This error has been corrected. Point 12 L69: please specify what kind of conversion (into economic foret?) A: Yes. I have completed it. Point 13 L74: replace affect for affects A: This error has been corrected. Point 14 L76: what kind of distribution? Vertical? A: Vertical Point 15 L69-76: in research goals I miss the comparison of the studied forest types and search for the best forest type for conversion (which is one of the main issues in the conclusions) Yes, I've added that. Point 16 Materials and Methods Figure 1: please add “the” before study site A: This error has been corrected. Point 17 L103-115: I suggest to replace this paragraph into the section 2.1. Study sites. A: I've moved it to 2.1. Point 18 L112: delete “old” A: This error has been corrected. Point 19 L145-146: I would suggest to connect these two sentences in to one ( …. because ….) as the second one is the explanation for the first one A: This sentence has been revised. Point 20 Data processing: Please specify here what the individual analyses were used for. Then it do not have to be specified in results. A: The individual analyses have been specified what they were used for Point 21 Table 1: Are those really information about plots? I think it is more about forest types. A: The title has been changed to” Basic information of different land use types”. Point 22 All abbreviations in the table should be explained (HF, CF, AF, CBF, LAI). A: All abbreviation have be explained. Point 23 There are some mean values – are that means from three replicates of forest types? It should be specified. It should be also specifies what the value after ± means. A: Yes, the mean values are that means from three replicates of forest types. I have completed below the table. Point 24 Please replace “Age” for “Forest age” A: This error has been corrected. Results Point 25 L181: please add “to” after decreased A: This error has been corrected. Point 26 L182: please add” , respectively” after …and CF A: This error has been corrected. Point 27 L183: CBF had (instead of has) A: This error has been corrected. Point 28 L185: Put the dot after the layer and start new sentence to be easier to understand: “The specific activity of 137Cs in CH and CF was 1.28 and 1.06 times greater in 0-10 cm layer compared to 10-20 cm layer, respectively. A: This error has been corrected. Point 29 Table 2: Because the layer is the same for all forest types, I suggest to replace it to the title of the table: 137C loss in the depth of 10-20 cm for different forest types. A: The loss of 137Cs is compared with the measured background value, not between soil layers, so the title cannot be changed. Point 30 Figure 2: It should be stated whether those are the mean values and what the error bars indicate. A: Statements have been completed below the Figure 2. Point 31 L218: this is the only place where you use the term “transition”. Did you mean conversion? This is my misuse of word. It should be “conversion”. Point 32 L222-223: It is not clear here what you compare, and please make the sentence shorter not repeating the same thing (The annual loss of topsoil nitrogen in HF, AF and CF was 1.51, 1.42 and 0.61 that of CBF, respectively.) A: This sentence has been revised according to your opinion. Point 33 Figure 4: All abbreviation should be explained (AF, CF …). What do the boxes show? (mean, median, percentiles?) A: All abbreviation have be explained. The boxplot consists of five statistics: minimum, upper quartile, median, lower quartile and maximum. The center of the boxplot is the median (It has been added in the article). Point 34 Figure 5: In the caption, use please carbon and nitrogen relative losses (instead SOC and TN). Plus the same comment as in Figure 5. A: The title has been revised. Comment has been completed below Figure 5. Discussion Point 35 L264: according to table 1, the litter thickness is 1.1-1.3 mm. I do not thing it corresponds to ”much litter cover”L265: I would be interested why there is no litter in AF and HF. These two questions will be revised together. What I want to convey is that the litter of CBF and CF is higher than that of AF and HF. The surface litter of AF and HF was not totally absent during our investigation, but rather very thin and could not be represented by data. These two sentences have been revised to “CBF and CF have more litter cover on the surface than HF and AF”. Point 36 Figure 6. if this is the result of another study, it should be quoted in the figure caption (adopted from …) A: It is not quoted from other papers. It is the relevant data measured by this experiment. It can not be logically combined with other results in the result part, so it is the theoretical basis of the discussion part. Point 37 Table 4: this output should be in the Results section A: The table and related analysis have been moved to the results section. Conclusions Point 38 L318: I would suggest to replace “forest transformation” to “conversion of coniferous broad-leaved mixed forest into the economic forest” to be clear and correspond with the overall text. A: This error has been corrected. Point 38 I miss here the conclusion drawn in lines 267-269, which is kind of practical. A: The missing conclusion has been supplemented.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The author's reply, and associated edits to the text, generally addressed my comments. My only remaining comment is that there are still some typos and grammatical errors, but these should be easy to fix.
Reviewer 2 Report
The manuscript has been sufficiently improved and I recomend it for publication
