Carbon, Nitrogen and Phosphorus Stoichiometry in Natural and Plantation Forests in China

Round 1

Reviewer 1 Report

Comments and suggestions for the authors follow in the attached file

Comments for author File: Comments.docx

Author Response

Reviewer #1: All Title/subtitle notations are incorrect.

>>> Thanks, we have fixed it.

 

>> “Samples and measurements”

• Detailed information on materials and methods has been previously published in other papers and the authors often refer to these papers. Yet, the manuscript would benefit from a short paragraph summarizing these absent data: plant species in NF and PL, growth stages, etc.;
• Number of samples: 2936 forest sites were considered, but how many samples were collected per site/per growth stage/per NF, PL?

>>> Thanks for your comments. We have added the plot details including samples, plant species of the two forest origins in Table S1. We have also added the detail information as “We divided the country into three grid sizes (100, 400 and 900 km²) based on vegetation distribution using a 1: 1,000,000 vegetation map. A grid size of 100 km² was designed for tropical and subtropical regions with rich species diversity, and 400 and 900 km² were for temperate and alpine vegetation regions where species diversity is relatively poor. Then we overlaid the grid maps with administrative maps and randomly select 3% to 5% of the grid for the field surveys by considering forest origin, age and type [25]”. 

• Litter sampling: in each 10 m² subplot were considered three 1mx1m sub(sub) plots? This must be clarified; according to the text each subplot is 10mx10m;

>>> Thanks. We have re-described the method of litter sampling as “We also set up three 1m×1 m quadrats in each subplot to for litter sampling.”.

• Correct 10x10m by 10mx10m (or consider 10x10m²).

>>> Thanks! We have corrected 10x10m by 10mx10m.

Figure 1 legend is incorrect, replace “nature forest” by “natural forest”

>>> Thanks for point out. We have fixed it now.

 

In all the figures and tables n, the number of samples considered, should be mentioned

>>> Thanks for your comment. The number of samples have added in all figures and tables.

Improve formatting of figures legends and add more elements to figure caption to facilitate interpretation

>>> Thanks for your suggestions. We have improved it.

 

 “Discussion”

• Last sentence of third paragraph: “However, decreased P in PL might be due to its low P-retention ability.” Explain/develop why there is a lower P retention ability.

>>> Thanks for your comment. We have explained the reason why there is a low P retention ability. We added “However, decreased P in PL might be due to its low P-retention ability, which mainly due to the loss form erosion, harvest and low efficiency of P retention system. Yu et al. [25] also hypothesized that the P loss caused by horizontal (i.e., surface and subsurface runoff) and vertical (i.e., leaching into subsoils) transport played an important role in systems with low P efficiency”.

• Last sentence of page 9: “Soil C:P ratios can act indicators” replace by “Soil C:P ratios can act as indicators”.

>>> Thanks, we have replaced “Soil C:P ratios can act indicators” by “Soil C:P ratios can act as indicators”.

• Paragraph “Factors affecting C, N and P concentrations and their stoichiometry in different succession stages in NF and PL”
• Line 9: “This may because” replace by “This may be because”

>>> Thanks, done.

• The authors aim to discuss the factors affecting C, N and P concentrations, yet, the discussion is mainly focused on the P concentrations. The authors start by introducing a small discussion on the impact of climatic factors on N concentrations: “Certain studies report that climatic factors only have a weak impact on plant N concentrations,…”, but the discussion ends by merely stating that temperature/precipitation affected the distribution of vegetation N. This final observation on N could be further developed.

>>> Thanks for your comments. The results of P concentrations were different between NF and PL. We try to explain it well in the next paragraph. But, we agree with you, and we have further developed this point by added these sentences “Moreover, MAP and MAT showed opposite effect on root and litter N content between NF and PL, while they were only significantly effect on soil N content in middle and later stage of NF. These results also suggested that plant species, rather than climatic variation, was the major determinant of plant N concentrations [55]”. These together with other sentences above can make our point.     

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript is interesting and addresses important environmental issues related to Carbon, nitrogen, and phosphorus stoichiometry in natural and plantation forests. The authors put a lot of work into downloading and developing material that was downloaded almost all over the country. But they made a few mistakes, namely:
1. In the Materials and methodology, do not clearly describe the way of performing the analyzes. In general, this chapter is treated only marginally.
I have not found any information on meteorological data for individual climatic zones. In figure 1. They appear to be the sampling sites (impressive) but these sites include warm temperate climate, moderate transitional, dry and extremely dry subtropics, mountain upland, tropical, and subtropics.
2. In the results, the authors compare, for example, in Figure 5 Changes in P concentration with latitude and longitude, mean annual precipitation (MAP), mean annual temperature (MAT), and height in various stands in the early stage (ES).
 And where are the precipitation and temperature dishes from 2011-to 2015?
On what basis do they draw their conclusions: "Overall, our results indicate that natural forests (NF) are more capable as growth progresses of storing P nutrients than plantations (PL). Different plant N: P ratios in NF and in PL during the progress of succession/growth suggests that the difference between forest origins should be considered in future research. Our study also reveals that geographical and climatic factors were not the dominant drivers of the differences in P concentrations between NF and PL in China, although more studies are still required to confirm this finding. " In my opinion, this is over-interpreted. N
Data should be completed and a closer look at them. Divide the material into years and climatic zones. The spinning samples collected in 2011 cannot be related to the conditions that prevailed from 2011-to 2015.
The authors did not separate the summary chapter, which in my opinion is very important.
The authors did not prepare the manuscript in accordance with the journal's requirements - references and the year of publication should be written in Bold

Author Response

Reviewer #2: The manuscript is interesting and addresses important environmental issues related to Carbon, nitrogen, and phosphorus stoichiometry in natural and plantation forests. The authors put a lot of work into downloading and developing material that was downloaded almost all over the country.

>>> Thanks for your comments. We have provide a point-by point response below.

But they made a few mistakes, namely:

1. In the Materials and methodology, do not clearly describe the way of performing the analyzes. In general, this chapter is treated only marginally.

>>> Thanks for your comments. As with the question posed by Reviewer 1, we have corrected the 'Materials and Methods' in detail. We have added the detail information as “We divided the country into three grid sizes (100, 400 and 900 km²) based on vegetation distribution using a 1: 1,000,000 vegetation map. A grid size of 100 km² was designed for tropical and subtropical regions with rich species diversity, and 400 and 900 km² were for temperate and alpine vegetation regions where species diversity is relatively poor. Then we overlaid the grid maps with administrative maps and randomly select 3% to 5% of the grid for the field surveys by considering forest origin, age and type [25]”. 

I have not found any information on meteorological data for individual climatic zones. In figure 1. They appear to be the sampling sites (impressive) but these sites include warm temperate climate, moderate transitional, dry and extremely dry subtropics, mountain upland, tropical, and subtropics.

>>> We appreciated it that Reviewer for asking this valuable question. We have also considered distinguishing climatic zones, but we have found that if we distinguish between climatic zones, there will be a situation where a succession stage does not have enough sample sites in a certain climatic zone, so we chose to focus on the national large-scale range between natural forest and plantation forest.

 

2. In the results, the authors compare, for example, in Figure 5 Changes in P concentration with latitude and longitude, mean annual precipitation (MAP), mean annual temperature (MAT), and height in various stands in the early stage (ES).

 And where are the precipitation and temperature dishes from 2011-to 2015?

>>> Thanks, we have added the MAT and MAP information in detail in 'Materials and Methods' as “Climate data (MAT and MAP) were obtained from the National Ecosystem Research Network of China (www.cnern.org.cn).”.

On what basis do they draw their conclusions: "Overall, our results indicate that natural forests (NF) are more capable as growth progresses of storing P nutrients than plantations (PL). Different plant N: P ratios in NF and in PL during the progress of succession/growth suggests that the difference between forest origins should be considered in future research. Our study also reveals that geographical and climatic factors were not the dominant drivers of the differences in P concentrations between NF and PL in China, although more studies are still required to confirm this finding. " In my opinion, this is over-interpreted.

>>> Thanks for your comments. We have rewritten this paragraph as our summary part. In this study, the most interesting things were that we found P concentrations significantly decreased in litter, root and soil in plantation forests (PL) as succession/growth proceeded, while the opposite occurred in natural forests (NF). Therefore, we think the results indicated NF maybe more capable as growth progresses of storing P nutrients than PL. We saw the different between forest origins, and think this should be considered in future research, and more studies are still required to have a solid conclusion.

Data should be completed and a closer look at them. Divide the material into years and climatic zones. The spinning samples collected in 2011 cannot be related to the conditions that prevailed from 2011-to 2015.

>>> Thanks for your comments. As mentioned above, if we divided the data into climatic zones, it will be not enough samples in a certain climatic zone for a succession stage, we want to focus on the different between forest origins among succession/growth stage. Moreover, our field sampling time was from 2011 to 2015, as the climate data also chose from 2011 to 2015. We have added this information in “Materials and Methods”.

The authors did not separate the summary chapter, which in my opinion is very important.

>>> Thanks, we have separate the conclusion to a summary chapter now.

The authors did not prepare the manuscript in accordance with the journal's requirements - references and the year of publication should be written in Bold

>>> Thanks for your reminder, we have bolded the year of the reference according to the submission manuscript format.  

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Thank you for sending the information and for indicating the appropriate page by the authors. in the current version, the manuscript is acceptable and if everything is fine, I accept it and in my opinion, it can be published.