Effects of Different Forest Types on Stoichiometric Characteristics of Carbon, Nitrogen, and Phosphorus in Tropical Soils, China

Round 1

Reviewer 1 Report

This study explored the soil C, N and P contents, along with their stoichiometric characteristics, soil microbial biomass and extracellular enzyme across various tropic forest types in China. Overall, the experimental design of this study is reasonable, and the data results are also reliable. However, I have a few suggestions and questions before acceptance.

The authors examined soil C:N, C:P, and N:P, as well as microbial biomass C:N, C:P, and N:P. Therefore, what's the correlation between the C:N:P ratios of soil microbial biomass and those of the soil itself? Is there a trend of increase with rising values, decrease, or no discernible change?

Vegetation type and soil water content had a considerable impact on microbial biomass carbon, nitrogen and phosphorus and extracellular enzyme activities, showing different spatial patterns in the four forest types. How did the authors consider the influence of these factors?

In this study, only four soil extracellular enzyme activities were measured at a single time point, without exploring the seasonal variations of these enzymes.

I think one of the most interesting finding in this study to be the P limitation, thus emphasizing the discussion on how soil extracellular enzymes adapt to this limitation. Again, some parts of the discussion seem quite flat. I suggest the authors remove the excessive description of results in the discussion section and focus more on the key discussion points regarding the novel findings of this study. For example, Part 4.1, 4.2 

I would suggest the authors consider including a conceptual diagram at the end to highlight the differences in soil total nutrients, available nutrients, microbial biomass nutrients, and the exoenzymatic stoichiometry characteristics among various tropical forest types.

Please Keep the number of the cited references to within 40.

Minor editing of English language required

Author Response

Thank you for reviewing our manuscript. Below I will respond to each of your suggestions.

1.Therefore, what's the correlation between the C:N:P ratios of soil microbial biomass and those of the soil itself?

I agree with your suggestion. In part 3.6 of the manuscript, we added the linear regression results of the ratio of soil C: N: P to microbial biomass C: N: P, available nutrient C: N: P, and enzyme activity (Figure 9). And it's described on line 284.

2.Vegetation type and soil water content had a considerable impact on microbial biomass carbon, nitrogen and phosphorus and extracellular enzyme activities,  showing different spatial patterns in the four forest types. How did the authors consider the influence of these  factors?

I agree with your suggestion. In part 3.6, we added the F value of the influence of forest type on soil C: N: P, microbial biomass C: N: P, available nutrient C: N: P and enzyme activity ratio to indicate the significant influence of forest type on the index (Table 2, row 291). As for water content, we listed it as soil background data in Section 2.2 without considering its impact on the index (Table 1, row 127).

3.I suggest the authors remove the excessive description of results in the discussion section and focus more on the key  discussion points regarding the novel findings of this study. For example, Part 4.1, 4.2.

I agree with your suggestion. In Discussion Section 4.1 and 4.2, we removed some of the unimportant descriptions of the results (lines 299, 302 and 315) and described the P-limiting results found in the study in more detail at lines 308, 326, 342, and 352.

4.I would suggest the authors consider including a conceptual diagram at the end to highlight the differences in soil  total nutrients, available nutrients, microbial biomass nutrients,  and the exoenzymatic stoichiometry characteristics among various tropical forest types.

I agree with your suggestion. At the end of the article, we submit the results of structural equation models for different forest types (Figure. S1) and describe them in line 272.

5.Please Keep the number of the cited references to within 40.

I agree with your suggestion. We have reduced the number of references to 40 and cited references from the last five years as much as possible.

Thank you again for your review and I hope my reply will be satisfactory to you. At the same time, we have submitted the latest revised manuscript for your confirmation. (Sorry, I discovered that I mistakenly uploaded the manuscript as a cover letter to the section responding to your review comments. And I don't know how to undo it. I will upload the revised manuscript in the correct place for your confirmation)

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear,

I am not convinced that the publication is at the appropriate level for this journal. Aspects that need to be improved for consideration to publication would be:

1- Strongly update references. The vast majority of articles cited are old, >= 5 years old. It is necessary to justify the research with more current things that report the problem and the need for studies on the subject.

2- It is necessary to locate the reader on the study area. Not everyone knows Chinese territory. A figure with the geolocation of the location where the data came from is required.

3- It is necessary to better design the experiment for the reader. A picture of the area where the experiment was conducted sounds appropriate.

4- The article talks about different specific characteristics of tropical soils, without providing an adequate characterization of these soils, nor where they are located. What is their temperature and humidity profile like? What climate are they located in?

5- Figures 1-4 are very bad. With a zoom of 175% I still cannot read the axes legend. These figures need to be improved.

6- Figure 6 in the discussion section is not at all reasonable. Results are results...discussion is discussion. Either you separate the sections, or you do everything together.

Author Response

Thank you for reviewing our manuscript. Below I will respond to each of your suggestions.

1. Strongly update references.

I agree with your suggestion. We have updated and cited references from the last five years, especially the introduction.

2. It is necessary to locate the reader on the study area.

I agree with your suggestion. In Section 2.2, we added the location diagram of the sampling points (Figure 2). For some reasons, we did not cite the picture of China's administrative divisions, so we gave a detailed description of the location of Hainan Province in Section 2.1, line 95.

3. It is necessary to better design the experiment for the reader. A picture of the area where the experiment was conducted sounds appropriate.

I agree with your suggestion. At the end of section 2.1, we added a photo of the sampling point (Figure 1).

4. The article talks about different specific characteristics of tropical soils,  without providing an adequate characterization of these soils, nor where they are located. What is their temperature and humidity profile like? What climate are they located in?

I agree with your suggestion. In Table 1 of Section 2.2, we added the basic physicochemical properties (water content, bulk density and pH) of soils of different forest types. The location of the sampling points is described in Section 2.2, line 114. In addition, in Section 2.1, we added more detailed climate data such as temperature and humidity for the study site (lines 99-104).

5. Figures 1-4 are very bad. With a zoom of 175% I still cannot read the axes legend. These figures need to be improved.

I agree with your suggestion. We adjusted the text of the pictures to make them clearer (they are now numbered as Figures 3-6).

6. Figure 6 in the discussion section is not at all reasonable.

I agree with your suggestion. We have made changes to section 4.4, and the images and descriptions have been moved to Section 3.4 (Figure 7, line 265).

Thank you again for your review and I hope my reply will be satisfactory to you. At the same time, we have submitted the latest revised manuscript for your confirmation.

Reviewer 3 Report

The manuscript entitled “Effects of different forest types on stoichiometric characteristics of carbon, nitrogen and phosphorus in tropical soils, China” investigated the basic elements, available nutrients, microbial biomass nutrients, and ecological enzymes in the soil of a primary forest, a secondary forest, and two kinds of plantation forests (Dacrycarpus imbricatus and Pinus caribaea Morelet) in tropical areas in China. The results showed that different forest types had significant effects on soil chemical properties and stoichiometric characteristics. The primary forest showed relatively good nutrient cycling. The manuscript is well written and organized. The results are fully explained, and the conclusions are clearly expressed. The comments for the manuscript are as follows：

1.      In the 3^rd paragraph of the Introduction section, the “C” in the beginning of the first sentence (line 42) is suggested to be changed to “Carbon (C)”.

2.      In the Materials and Methods section 2.2, the sentence “Within each replicate, 5 individual samples of 0-143 10cm, 10-20cm, 20-30cm depth were made separately using a soil auger with a 5 cm inner 144 diameter and mixed to form one sample.” (line 143-145) should be revised to make its meaning clearer for understanding.

3.      The resolution of all the figures should be improved. The word size of X and Y axis should be enlarged to make them legible.

4.      For the figures (1-5), titles are missing. For example, figure 1 is mainly about the soil basic elements.

5.      For the figure 6, the figure title and the figure caption should be separated.

6.      The references should to be carefully checked and revised. The doi of the references were doubled.

The English of the manuscript is good. The manuscript is clearly written.

Author Response

Thank you for reviewing our manuscript. Below I will respond to each of your suggestions.

1.In the 3rd paragraph of the Introduction section,  the “C” in the beginning of the first sentence (line 42) is suggested to be changed to “Carbon (C)”.

I agree with your suggestion. In line 42, we have changed this.

2.In the Materials and Methods section 2.2, the sentence "Within each replicate, 5 individual samples of 0-143 10cm, 10-20cm,  20-30cm depth were made separately using a soil auger with a 5 cm inner 144 diameter and mixed to form one sample.”  (line 143-145) should be revised to make its meaning clearer for understanding.

I agree with your suggestion. We have modified this to make it more explicit (lines 122-126).

3.The resolution of all the figures should be improved. The word size of X and Y axis should be enlarged to make them legible.

I agree with your suggestion. We adjusted the images to make them clearer (they are now numbered as Figures 3-7).

4. For the figures (1-5), titles are missing. For example, figure 1 is mainly about the soil basic elements.

I agree with your suggestion. We have added titles to the figures (now numbered as Figures 3-6 and 8).

5.For the figure 6, the figure title and the figure caption should be separated.

I agree with your suggestion. We have adjusted the title and comment of Figure 6 (now numbered as Figure 7).

6.The references should to be carefully checked and revised. The doi of the references were doubled.

I agree with your suggestion. We have revised the reference to bring it up to standard.

Thank you again for your review and I hope my reply will be satisfactory to you. At the same time, we have submitted the latest revised manuscript for your confirmation.

Round 2

Reviewer 2 Report

I believe the modification suggestions were made. Therefore, I recommend acceptance.