Estimating Structure and Biomass of a Secondary Atlantic Forest in Brazil Using Fourier Transforms of Vertical Profiles Derived from UAV Photogrammetry Point Clouds

Round 1

Reviewer 1 Report

This manuscript tested the performance of 3D products derived from DAP and a technique based on Fourier transforms of vertical profiles of vegetation to estimate AGB and other forest attributes of interest in a secondary fragment of Atlantic Forest located in northeast Brazil. The Fourier transforms of vertical profiles is a new method to derive lidar metrics. The application on the special secondary frament of Atlantic forest should be new. The accuracy is promising. The writing is lengthy and completed. I can not find major weakness for this sparse forest type. However, many questions are remained.

Is it possible to apply your methods on dense forests or steep mountain areas? The elevation values collected with the GNSS in RTK mode varied between 15 and 45 m. The surface looks so flat. How about the slope distribution in the whole areas of Atlantic Forest?

What is the minmimum canopy cover or gap to allow DAP seeing the ground?

What is the efficiency to cover larger area? Multi-motor UAV can not last for a long time for flying a large area.

Please reply to these general questions. Specific comments are as follows:

1. In Materials and methods section, major species should be introduced in Characterization of the study site.
2. Line 139: “Before the beginning of the inventory of each plot, at least five height estimates of the trees were also performed with the aid of a Haglöf electronic clinometer (Hcor).” ‘At least’ means thetotal tree number should be larger than 150. However, you mentioned that “The differences between the tree heights (n = 150) estimated by the trigonometric (c-linometer) and visual methods are presented in Figure 3.”. So, ‘at least’ could be deleted.

Author Response

We thank the editor and all three reviewers very much for the careful review and valuable comments that improve the paper a lot. We have addressed all of the comments carefully. All the changes made throughout the paper in response to the reviewers’ comments are explained point-by-point below.

Author Response File: Author Response.docx

Reviewer 2 Report

The work done by authors is quite an interesting and somewhat new concept.  However, some suggestions are proposed for further improvement.

1. LN122: Why did you select August and October 2018? If it has any specific reason, please mention it.
2. Figure 4: Please add basic map components (North arrow and scale bar) to the a,b. Better to add image capture date and time for a-d.
3. There are so many abbreviations, and they are affecting the readability of the manuscript. It is better to add an abbreviation table.
4. LN 137-138 “The total height values (Hobs) of the trees were estimated visually by a trained observer” I supposed that calculating height by visually may not bring accurate results. Better to use some scientific method/s.  

Author Response

We thank the editor and all three reviewers very much for the careful review and valuable comments that improve the paper a lot. We have addressed all of the comments carefully. All the changes made throughout the paper in response to the reviewers’ comments are explained point-by-point below.

Author Response File: Author Response.docx

Reviewer 3 Report

The work done by authors is quite an interesting and somewhat new concept.  However, some suggestions are proposed for further improvement.

1. LN122: Why did you select August and October 2018? If it has any specific reason, please mention it.
2. Figure 4: Please add basic map components (North arrow and scale bar) to the a,b. Better to add image capture date and time for a-d.
3. There are so many abbreviations, and they are affecting the readability of the manuscript. It is better to add an abbreviation table.
4. LN 137-138 “The total height values (Hobs) of the trees were estimated visually by a trained observer” I supposed that calculating height by visually may not bring accurate results. Better to use some scientific method/s.  

Author Response

We thank the editor and all three reviewers very much for the careful review and valuable comments that improve the paper a lot. We have addressed all of the comments carefully. All the changes made throughout the paper in response to the reviewers’ comments are explained point-by-point below.

Author Response File: Author Response.docx

Reviewer 4 Report

The paper is interesting an it presents a satisfactory contribution to the body of knowledge.

Abstract:

Lines 4,8 and 21 authors could specify which are these other poducts.

Introduction:

lines 80-84 why?

line 93 another time which others?

Material and methods:

Line 99: authors should give the exactly study area covers.

line 100 could add principal species are present in the study area

line 139 why five? some reference should be given.

line 245 any reference in why use 2.5 value?

Results are clearly presented

Discussion is extensive and appropiate described

Author Response

We thank the editor and all three reviewers very much for the careful review and valuable comments that improve the paper a lot. We have addressed all of the comments carefully. All the changes made throughout the paper in response to the reviewers’ comments are explained point-by-point below.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

All questions have been answered. It is able to be published.

Reviewer 2 Report

The manuscript has been improved. 

Reviewer 3 Report

The article has improved by incorporating the reviewer's comments.