Piling Secondary Subtropical Forest Residue: Long-Term Impacts on Soil, Trees, and Weeds

Round 1

Reviewer 1 Report

The manuscript entitled “Piling secondary subtropical forest residue: long-term impacts on soil, trees, and weeds” aims to assess the different impacts of residue piling on soil properties, and vascular plants in secondary subtropical forest in Brazil. By designing suitable plants intercepting horizontal transects, they explicitly measured the plant height, herbaceous weeds biomass, soil chemical content as well as the Normalized Difference Vegetation Index using drone. They found residue piled areas exhibited a decrease in soil pH and an increase in available soil P and K. Although residue piling areas enhanced herbaceous and shrub weed biomass increased 2.5 to 10 times, there is weak promotion on pine growth. Overall, this work has clear study objectives, solid data and interesting findings, which will provide vital merits on the management practices such as increasing soil nutrition, reducing negative environmental effects, and ensuring forest productivity and sustainability. 

The below is my minor suggestion:

1）Adding a diagrammatic sketch to illustrate how the transect was displayed and how the samples plots were design.

2）It would be better to supply the detail sampling time

3) NDVI is very nice indices to reflect the forest structure and productivity, but the current text did not show how to convert the drone image to the NDVI indices, and how the accurately match the filed plot positions with drone image. 

4) I suggest the authors further the stoichiometry of different soil properties, rather than focusing on the analysis of individual variables.

5) Separate the results and discussion sections into two individual parts.

6) In the context of carbon neutrality, some references could be cited to link this work to be more depth and meaning if showing whether or/and how or to what extent the residue piling management could promote the soil and aboveground carbon storage. These are two examples:

Li et al. 2021. Crystal-phase-engineering of PdCu nanoalloys facilitates selective hydrodeoxygenation at room temperature

Wang et al. 2021. Technologies and perspectives for achieving carbon neutrality

Author Response

Obrigado por seu tempo e críticos positivos em relação ao nosso manuscrito intitulado “Pilhagem de manuscritos florestais subtropicais secundários: impactos de longo prazo no solo, árvores e ervas daninhas” (ID do manuscrito: forest-1763030). As respostas positivas dos revisores foram muito úteis para melhorar o manuscrito. Obrigado pelas sugestões.

Sugestões de revisão, grandes mudanças foram feitas na seção de processo de materiais e métodos para revisão. Por favor, nossas respostas abaixo respostas aos comentários dos comentários em vermelho.

Obrigado novamente.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript “Piling secondary subtropical forest residue: long-term impacts on soil, trees, and weeds” provided a better understanding on the role of piling in affecting forest ecosystem functioning and structure.

 Line 35:  clarify the mean of “shrub weed biomass”. Weed in this manuscript was used in many parts, and I think this word should be clarified and is accord with the trait of manuscript.

Line 104-108: authors should add the content of objectives or hypothesis of this manuscript.

Line 147: clarify the sampling size of the transect line, including length and width.

Line 211: definite the version of R.

Line 222: table 1 is not a good display, and revise this table. The difference was among sites or soil depths? P value did not showed better information, and the capital letter has unclear meaning. The manuscript contains similar problem in following tables.

Author Response

Obrigado por seu tempo e críticas construtivas em relação ao nosso manuscrito intitulado “Pilhagem de resíduos florestais subtropicais secundários: impactos de longo prazo no solo, árvores e ervas daninhas” (ID do manuscrito: forest-1763030). As respostas positivas dos revisores foram muito úteis para melhorar o manuscrito. Obrigado pelas sugestões.

Seguindo sugestões de revisão, grandes mudanças foram feitas na seção de materiais e métodos para esclarecer o processo de amostragem. Por favor, encontre nossas respostas aos comentários dos revisores abaixo em vermelho.

Obrigado novamente.

Author Response File: Author Response.docx

Reviewer 3 Report

The work presented for review is very interesting. Importantly, the research results are based on long-term experience lasting up to 3 decades. The discussed issue is important from the point of view of forest management and the ongoing discussion on how to deal with felling residues.

The work is multifaceted and includes both the results of biometric measurements of plants, chemical analyzes of soil and plants, as well as a modern analysis of NDVI indicators of photos taken from a drone.

The text of the work is written in clear language, the methodology of the research and the research methods used are correct. The analysis of the results was performed correctly. The concluded conclusions summarize the obtained research results

Author Response

Revisor:

Obrigado por seu tempo e críticas construtivas em relação ao nosso manuscrito intitulado “Pilhagem de resíduos florestais subtropicais secundários: impactos de longo prazo no solo, árvores e ervas daninhas” (ID do manuscrito: forest-1763030). As respostas positivas dos revisores foram muito úteis para melhorar o manuscrito. Obrigado pelas sugestões.

Seguindo sugestões de revisão, grandes mudanças foram feitas na seção de materiais e métodos para esclarecer o processo de amostragem. Por favor, encontre nossas respostas aos comentários dos revisores abaixo em vermelho.

Obrigado novamente

Author Response File: Author Response.docx

Reviewer 4 Report

The paper entitled “Piling secondary subtropical forest residue: long-term impacts on soil, trees, and weeds” focuses on the effects of the practice to accumulate forest slash piling on a Brazilian ecosystem. Various interesting parameters are taken in account to delineate a causal effect on forest grown inside the piling areas and outside the piling areas.

Overall the manuscript is well written, interesting and based on relevant hypothesis. However I have some of major methodological concerns:

a)    I’m sorry I don’t understand completely your experimental design. At lines 147-151 you describe transects 300 meters long intersecting 5 residue piling areas that have been sampled “systematically” every 7.5 meters. How many transects did you have? How was this repeated in the 3 areas? Math tells me you should have 40 samples per transect. However at line 183 you report that “5 soil samples per transect were collected”. Please explain better how many transects and how many samples were collected (and composited) for each sample. Also please specify how many technical replicates (I.e. repeated measures of the same sample) was performed for each analysis. Please report the number in the tables caption. 

b)    As far as I understand you collect data in the transect(s) and based on the sampling point position you assign the sample to IP (inside the piling) and OP (Outside the piling). B1) How could you assign the sampling point to each category in a certain way? B2) Along the transect the number of samples falling in IP and OP might not be the same: did you have an unbalanced statistical design? How many samples you had in IP and in OP in your research?

c)    This is the most important: you discussed changes in the analyzed parameters as caused by the historical piling process. How could exclude other local factors of variation? Was the soil in the 3 areas so uniform? Were preliminary soil analyses performed? Are there data on texture, Cation Exchange Capacity, and on other possible interfering characteristics? There could have been some differences in the parent rock that might confuse your data?

d)    You analyzed total carbon content and discussed the data as ORGANIC carbon content. Also in the conclusion (Lines 369-371). I agree organic carbon is a parameter of major importance in soil, but this is not what you measured based on line 189. Please rephrase.

e)    There is an aspect missing in this study: soil microbiology. In a future work please consider studying soil enzymatic activities and/or microbial biomass or soil respiration.

 Minor comments:

Line 66 depends should read depend

Lines 66-76 in 10 lines the world “amount” is repeated 6 times. Please try rephrasing.

The aim of the present study should explicitly stated at the end of the introduction. 

Line 369: You should not draw the major take home message of your study from a parameter you did not evaluate directly.

Author Response

Revisor

Obrigado por seu tempo e críticas construtivas em relação ao nosso manuscrito intitulado “Pilhagem de resíduos florestais subtropicais secundários: impactos de longo prazo no solo, árvores e ervas daninhas” (ID do manuscrito: forest-1763030). As respostas positivas dos revisores foram muito úteis para melhorar o manuscrito. Obrigado pelas sugestões.

Seguindo sugestões de revisão, grandes mudanças foram feitas na seção de materiais e métodos para esclarecer o processo de amostragem. Por favor, encontre nossas respostas aos comentários dos revisores abaixo em vermelho.

Obrigado novamente

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The munuscript have been revised better, and this vesion can be accepted in my mind.

Reviewer 4 Report

All the points I raised in the previous review have been replied.

I thank the authors and suggest the manuscript for publication.