Mapping of the Successional Stage of a Secondary Forest Using Point Clouds Derived from UAV Photogrammetry

Round 1

Reviewer 1 Report

This study classifies the stage of ecological succession in Areas of the Atlantic Forest with the use of Cloud of Aerial and Terrestrial 3D Points. The topic is interesting, but several issues should be considered before publication:

Major comments:

The manuscript needs extensive revision for language and grammar.

For example:

Line 61: Please rewrite this sentence

“, state that accurate forest inventories improve confidence in forest management decision-making.[8][9][10]”

Line 73. Please put the full stop (.) after the references.

What is the scientific contribution of this work? What is the research gap addressed by this study?

Authors should comprehensively explain the existing methods for classifying forest ecological succession and their limitations, and how your work addresses those limitations.

I would suggest adding more detailed information about the control points. What was the distribution of these points for each study area? 

Minor comments

Title:

Please use “Successional” instead of “Sucessional”.

Please use “3D” instead of “3d”.

Abstract:

The abstract is too long. I would suggest that the authors limit the abstract to around 300 words given the instructions for authors provided at https://www.mdpi.com/journal/remotesensing/instructions.

I would suggest adding two more keywords. For example, “Atlantic Forest” and “classification” can be included in the keywords.

Introduction:

Line 61: Please rewrite this sentence

“, state that accurate forest inventories improve confidence in forest management decision-making.[8][9][10]”

Line 69: What does "IFTs" mean? Interpreted Forest Types??

Please write the full name first.

Line 116: please remove this line

Figure 1. Please add a scale for each map. What is the source of these maps? Google earth?

Figure 2. This figure is not readable. Please write in English 

Author Response

"Please see the attachment."

Author Response File: Author Response.docx

Reviewer 2 Report

General comments

In general this is research that should  be published.

I do not have the statistical expertise to fully evaluate the point cloud quality criteria but it seems in line with the data I have seen in other studies.   

I found the use of abbreviation difficult to follow. I don’t know in the use of ab ab and ba for basal area is a method to differentiate  plot measures from point cloud.  I am not sure because several other abbreviations  also do not follow the English word order.  It seems dap is used for manual dbh  and DAP  for drone aerial photography but the capitalization is very hard to follow.

Between lline 500 and 700 there are so many abbreviations that are not consistently used I found the reasoning hard to follow.  From what I can make out the methodology seems sound and the results similar to the general findings of these technologies.

For example table 10  has so many undefined acronyms as to be incomprehensible

Figures are not all in English fonts are too small  are not distinct even when magnified.

There is a real need to use clear and consistent acronyms and abbreviations and careful attention to capitalization of them.   

I am not sure that I can agree with the cost benefit analysis of the manual method.  Small plots are used with some type of statistical design to represent a wider area.  I am not sure that I agree with using only the area of the plot as a denominator in the cost calculation is justified.  Alternatively do you really need the expense of RTK equipment to do the drone survey for the vegetational stage comparisons.

I see two papers in this manuscript. 1 Performance of drones in this vegetation type.  In this I believe the results are a confirmation that drone SfM works equally well in this vegetation as in other ecosystems across the globe.

2. For classification of succession  for the CONAMA   procedure drone based aerial photography by small drones can be a very cost effective technology.  This paper could stress the wide ranges of tree height in the classification which can be adequately addressed even with the inaccuracies of the drone-based system.

Specific comments

Line 49  conservation not conversation

Line 50  as being mainly responsible for climate change.

Line 61 Author missing at beginning of sentence  which of 8 ,9 or 10 said this.

Line 66 population to be studied.

Line 69 ITF ?  Traditional Forest Inventory ?

Line79- 84 a very well written paragraph.

Line 92 Atlantic forest Biome  need a little better definition  I would guess it is what North Americans call the Amazon rain forest  or is it the non-mountainous section   or coastal plain?

Line 100 forest settlements?  Seems you are discussing stands or at least vegetation homogeneity.  Settlement would imply human clearings.  Or are you referring to  remnants of roving slash and burn agriculture . 

Line 105 liabilities?   Why this negative word. Would not ecological values, or biodiversity be better.  

Line 107-109 this non-sentence  answers several questions I had reading the above paragraph.

Figure  are not in English and font is very small

Line 138 CONAMA resolution 29/24  this needs to be defined.   reader shouldn’t be required to look it up on Google.    

Line 140 – 144  need to be consistent  dap = dbh  ab = ba   h=ht?

Line 196 aswes? Local name?  misspelled?

Line 222 rpa   RPA ?

Line 226 terrain control point why PCT     I guess word order changes with translation.

Line 266 DTM is standard abbreviation.

Line 271 do you mean inverse distance weighting

Line  384 SMEHOROUS   I can find no definition in English or Portuguese translator

Line 453 r 2 of 8.7 .87?  or 8.7%  .087

Line 457 move references to end of sentence.

Figure 5 caption  needs to define the abbreviations  VS VSM  VSME etc.  caption should define all terms in the figure without need to reference the text.

Line 547  reference should be after by, .  The sentence would read better if the authors of [10] were listed.

Table 15 DAP-RPA  data acquisition cost R$83,40   83.40 ? Ok 83.40 in text

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Accept in present form

Author Response

Thanks for the contributions! We are happy that we were able to respond to all the suggestions.

Reviewer 2 Report

I complement you on the thorough revisions you have done on this paper. My last small comment . I think a small inset of South America on the location map with a star or other mark on the location of the study. Since this is an international journal readers from other continents might find that helpful. Since you have included latitude  and longitude  it  is not absolutely necessary  but  might make it easier for an international reader. 

Author Response

Thanks for the contributions! We are happy that we were able to respond to all the suggestions. The map of South America was included in the location map in the manuscript and it really got that much better. We have also included the corrected figure in the .zip file with all the figures.