Modeling and Spatialization of Biomass and Carbon Stock Using LiDAR Metrics in Tropical Dry Forest, Brazil
, José Antônio Aleixo da Silva 2, Robson Borges de Lima 1,*, Emanuel Araújo Silva 2, Anderson Francisco da Silva 2, Josias Divino Silva de Lucena 2, Nattan Adler Tavares dos Santos 2, Iran Jorge Corrêa Lopes 3, Mayara Maria de Lima Pessoa 2 and Cybelle Laís Souto-Maior Sales de Melo 2Round 1
Reviewer 1 Report
Dear authors,
Regarding the article “Modeling and spatialization of biomass and carbon stock using Lidar metrics in tropical dry forest, Brazil: Preliminary results”. I would like to say that in general the article is interesting, even if Lidar is a well-known technology and the novelty of the work is in an average range, it is always appreciating the application of this technology in different types of ecosystems, as in the Caatinga vegetation. The article is written in a clear English with an interesting data elaboration. However, there is some issues with the format, specially in the way of citing and references. The validation is not clear (conventional forest inventory), there are no references regarding the allometric equations used in the research. More suggestion can be seen in the specific comments.
General comments:
I encourage the authors to read the formatting guidelines carefully due some inconsistences in the references. Please, be consistent with the format of the journal. Use only numbers and not name of the authors (e.g., Dalla-Lana et al. 2019, Brown and Lugo, 1982, Roy et al. 2001, Malhi et al. 2004, Elias and Potvin, 2003, Jansen 2005, Crookston and Finley, 2007, Silva et al. 2007, Magnusson et al. 2007, etc.). Including also the technical reports (IBGE, 2012, EMBRAPA, 2007, Agritempo, 2018, etc.)
These have to be added in the references section. Therefore, reorder the numbering both in the text and in the references section.
Review carefully the text, a typing error was found in line 49, a letter is missing in “In many cases” and in table 2 was written “Atributo” instead of “Attribute”, “Valores”, instead of “Values” and “Data de aquisição” instead of “Data acquisition”.
In acknowledgments three researchers are mentioned, but they are also mentioned as co-authors. If it is just coincidence of names, it is completely fine. But if they are the same persons there is no reason to acknowledge them. If they qualify for authorship keep their names as co-authors and delete it in acknowledgments (see more details in Instructions for Authors: https://www.mdpi.com/journal/forests/instructions#authorship). Otherwise, delete the names as co-authors and keep it in acknowledgments.
Specific comments:
|
Row |
Commented text |
Note |
|
126 |
The vegetation in these areas is predominantly Caatinga (dry tropical forest). |
Please, describe deeper the vegetation in the material and methods. You should mention at least the dominant species with scientific names in order to familiarize better to the (international) reader with the type of vegetation that the paper is dealing. |
|
154 |
Absolute square errors (RMSE) of 18.28 kg. trees-1and bias of 0.20 kg.trees-1. |
Use the right abbreviation “Root Mean Square Error” (RMSE). As in line 146 was mentioned that equation 1 was previously developed. I strongly suggest to present the RMSE and bias in percentage and not in units as kg.trees-1. Specially, considering that developing allometric equations in shrubs species follow different strategies of fitting. DBH is not a suitable covariable in shrubs and it is recommended use crown areas or crown volumes as covariables in these cases. Therefore, in this way the validation of the equation is clearer. |
|
170 |
Table 1. Descriptive values (mean and standard deviation). |
If you could add the minimum and maximum values, the readers can have a better overview of the data set. |
|
280 |
The model parameters were estimated using the Ordinary Least Squares (OLS – Ordinary Least Squares). |
Delete “Ordinary Least Squares” inside the brackets. |
|
299 |
Figure 4. LiDAR data(.las). MDT and MDS. |
Use the right abbreviation Digital Terrain Model (DTM) Digital Surface Model (DSM) In lines 67 and 68 the abbreviations are correct. Apparently, the Canopy Height Model (CHM) is missing in the part of LiDAR data (.las) flowchart. |
|
299 |
Figure 4. Forest inventory. 2014 biomass generation (local equation). |
Is there any technical report or scientific publication from 2014 where the local allometric equation can be cited? |
|
355 |
The estimated average density of TAGB and TAGC for the Transposição area was 9.2 ± 6.1 Mg.ha-1 and 4.6 ± 14 Mg.ha-1, respectively. |
In line 353 it was mentioned that the carbon fraction used was 0.48, thus if the total aboveground biomass was 9.2, with this carbon fraction the total aboveground carbon should be 4.4 and not 4.6. Probably, the difference can come from the full data set using more decimals. Otherwise, you applied a carbon fraction of 0.50 as you wrote in line 159. Please, double check. |
|
363 |
Figure 6 |
Please, write the units as Mg ha-1, instead of Mg/ha |
Author Response
Responses to general comments
General comments:
I encourage authors to read the formatting guidelines carefully due to some inconsistencies in the references. Please be consistent with the format of the magazine. Use only numbers and not the authors' names (for example, Dalla-Lana et al. 2019, Brown and Lugo, 1982, Roy et al. 2001, Malhi et al. 2004, Elias and Potvin, 2003, Jansen 2005, Crookston and Finley, 2007, Silva et al. 2007, Magnusson et al. 2007, etc.). Also including technical reports (IBGE, 2012, EMBRAPA, 2007, Agritempo, 2018, etc.)
These must be added in the references section. Therefore, reorder the numbering both in the text and in the reference section.
Review the text carefully, a typo was found on line 49, a letter is missing in “In many cases” and in Table 2, “Attribute” instead of “Attribute”, “Values” instead of “Values” is written and “Acquisition date” instead of “Data acquisition”.
Answer: Modifications made to the main text
In the acknowledgments, three researchers are mentioned, but also mentioned as co-authors. If it's just a coincidence of names, that's okay. But if they are the same people, there is no reason to recognize them. If they qualify for authorship, keep their names as co-authors and exclude them in the acknowledgments (see more details in the Instructions for Authors: https://www.mdpi.com/journal/forests/instructions#authorship). Otherwise, exclude the names as co-authors and keep them in thanks.
Answer: Modifications made to the main text
Author Response File: 
Author Response.docx
Reviewer 2 Report
In the manuscript “Modeling and Spatialization of Biomass and Carbon Stock Using Lidar Metrics in Tropical Dry Forest, Brazil: Preliminary Result” authors estimate biomass and carbon stock using Lidar data matrices and two models. The study is valuable to understand the carbon sequestration in the dry tropical forest, however a loophole is that the limited application for other forests. I have several comments to improve the manuscript.
Title: subtitle (Preliminary Result) seems unnecessary for the title
Abstract: The objective is not clearly stated. The results are lean in the abstract.
L 27: What these acronym stands for? TAGB and TAGC
I did not see full description on those terms throughout the manuscript
Introduction:
L 64-70: The paragraph seems pretty general information, where readers already know that Lidar point could data can used to create DEM, DSM, canopy height models.
Materials and Methods:
L 133: Symbol: km
L 137: Not italic Figure 3.
L150: When it derives biomass equations, it needs to indicate rainfall and forest type information. Some information has given earlier but it worth to mention here as well.
Here is an example authors can find the particular information with biomass equations.
Kuruppuarachchi, K. A. J. M., Gamini Seneviratne, and D. Madurapperuma. "Carbon sequestration in tropical forest stands: its control by plant, soil and climatic factors." (2016).
L 157: number citation (Dalla-Lana et al. 2019)
L 159-161: Use number citation instead of author, year citation
Table 2: Give English terminology - Atributo, Valores, Data de aquisiçã
L 298: Spelling mistake “Figura 4”
L298: Figure 4: What MDT and MDS acronym stands for?
Results:
L 203: Fusion is a cool tool to obtain Lidar metrics. The table gives only Lidar metrics and symbology but it is good to give some values for each matrix.
Visualization plot metrics with profile and overhead view would be nice. You can find more information from the following tutorial.
http://gsp.humboldt.edu/OLM/Courses/GSP_326/lidar_introductory_lab/instructions.html
L 252: Pearson's correlation metrics is useful to see how variables correlate. So it is good to give a Pearson's correlation plot metrics to see the multicollinearity.
L 387: Anderson et al. [19]
Conclusions:
Generally, a summary paragraph is given for the conclusions beside bullet points.
Author Response
Responses to general comments
- Title: subtitle (Preliminary Result) seems unnecessary for the title
Answer: It has been removed from the title of the manuscript
- Summary: The objective is not clearly defined. The results are dry in the abstract
Answer: the objective was to quantify biomass and carbon stock using LiDAR metrics.
- L 27: What does this acronym mean? TAGB and TAGC
Answer: Means above-ground total biomass and above-ground total carbon, respectively
- L 64-70: The paragraph looks like very general information, where readers already know that the data from the Lidar point can be used to create DEM, DSM, canopy height models.
Answer: For the authors, this information is important because it brings a little bit of the basic concept and applications of the LiDAR tool.
- Materials and methods:
- L 133: Symbol: km
Answer: Corrected in the main text
- L 137: Without italics Figure 3.
Answer: Corrected in the main text
- L 157: number citation (Dalla-Lana et al. 2019)
Answer: Corrected in the main text
- L 159-161: Use the citation number instead of the author, year of citation
Answer: Corrected in the main text
- Table 2: Provide terminology in English - Attribute, Values, Date of purchase
Answer: Corrected in the main text
- L 298: Spelling error “Figure 4”
Answer: Corrected in the main text
- L298: Figure 4: What is the acronym MDT and MDS?
Answer: Corrected in the main text - the correct one is DTM and DSM, Digital Terrain Model and Digital Surface Model
- L 252: Pearson's correlation metric is useful to see how the variables correlate. Therefore, it is good to provide the Pearson correlation graph metrics to see multicollinearity.
Answer: We use multivariate methods to select variables with a high degree of correlation
- L 387: Anderson et al. [19]
Answer: Corrected in the main text
- Conclusions: Generally, a summary paragraph is provided for the conclusions next to the markers
Answer: Corrected in the main text
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear authors,
The manuscript was improved substantially, and it is really appreciating the effort in formatting the manuscript regarding cites and references. Valuable information was added, such as the main dominant species of Caatinga vegetation, the minimum and maximum values in table 1 and the inclusion of the CHM in figure 4. However, two important issues have to be solved 1) The figures 1 and 2 were found in Pereira de Oliveira et al. 2021 “Prediction of biomass in dry tropical forests: An approach on the importance of total height in the development of local and pan-tropical models. Therefore, it is highly recommended modify the layout of the figures or cite them as Pereira de Oliveira et al. 2021 in the manuscript. On the other hand, the full text between lines 114 and 120 was found in the previous paper mentioned. Please, modify the text, including the figures descriptions. 2) The RMSE (3.31 %) mentioned in line 156 is too low, probably there is an error of typing or in the way how the error was computed. Not even in pine plantation is possible to obtain such low errors. Due to the structure (architecture) of the shrubs (as we can appreciate in figure 1C), we expect higher errors. Authors as Huff et al. 2017 or Kralicek et al. 2017 reported higher values in RMSE (%) regarding shrub species. In case of Caatinga vegetation, according to Dalla Lana et al. 2018, this type of species (e.g., Mimosa ophthalmocentra and Poincianella bracteosa, which are part of this study.) present an error in a range of 18.6 to 54.5 % according to the Furnival Index. Please, double check this value.
Below, some small suggestion that could improve the quality of the manuscript:
If you change the title, deleting “Preliminary results”. Please, modify line 29 and instead of “Our preliminary results provide …” write “Our finding provides …”
A suggestion in the keywords “caatinga vegetation; aboveground biomass; carbon stocks; allometry; statistical models”
Add “total” height (Ht) in line 55 to match the text with the abbreviation in parenthesis as it was written in line 146. The same in line 153.
In figure 3, remove the accent in “Tmax”
In line 227 the cite (R Development Core Team, 2017), if the analysis was carried out recently, the cite should be updated as R Core Team, 2021 and please, remove the word “Development” and transform this cite in number [28]. The same in line 272.
Please, modify lines 466 to 469 because the same text was found in Pereira de Oliveira et al. 2021
Author Response
1) The figures 1 and 2 were found in Pereira de Oliveira et al. 2021 “Prediction of biomass in dry tropical forests: An approach on the importance of total height in the development of local and pan-tropical models. Therefore, it is highly recommended modify the layout of the figures or cite them as Pereira de Oliveira et al. 2021 in the manuscript. On the other hand, the full text between lines 114 and 120 was found in the previous paper mentioned. Please, modify the text, including the figures descriptions.
answer: Change made in the manuscript including the citation [22] for Oliveira et al. 2021
2) The RMSE (3.31%) mentioned in line 156 is very low, there is probably a typo or in the way the error was calculated. Even when planting pine trees it is not possible to obtain such low errors. Due to the structure (architecture) of the bushes (as we can see in figure 1C), we expect bigger errors. Authors such as Huff et al. 2017 or Kralicek et al. 2017 reported higher values in the RMSE (%) in relation to shrub species. In the case of Caatinga vegetation, according to Dalla Lana et al. 2018, this type of species (for example, Mimosa ophthalmocentra and Poincianella bracteosa, which are part of this study) presents an error in the range of 18.6 to 54.5% according to the Furnival Index. Please check this value.
Answer: The values of RMSE% and bias % have been corrected in the manuscript to (RMSE) of 18.2% and bias of 0.20%, respectively . In the article by Oliveira et al. 2021 this values should be in percentage order.
Below, a small suggestion that can improve the quality of the manuscript:
If you change the title, excluding “Preliminary results”. Please modify line 29 and, instead of "Our preliminary results provide ...", write "Our discovery provides ..."
Answer: Correction added in the manuscript
A suggestion in the keywords “caatinga vegetation; above-ground biomass; carbon stocks; allometry; statistical models ”
Answer: Correction added in the manuscript
Add the “total” height (Ht) in line 55 to combine the text with the abbreviation in parentheses as it was written in line 146. The same in line 153.
Answer: Correction added in the manuscript
In figure 3, remove the accent in “Tmax”
Answer: Correction added in the manuscript
In line 227 of the quote (R Development Core Team, 2017), if the analysis was carried out recently, the quote should be updated as R Core Team, 2021 and please remove the word “Development” and make this quote into the number [28 ] The same on line 272.
Answer: As the analyzes come from 2017 of Cinthia Oliveira's doctoral thesis, the analyzes were carried out in 2017 with the 2017 R project.
Modify lines 466 to 469 because the same text was found in Pereira de Oliveira et al. 2021
Answer: This acknowledgment is continuous because the publication of the article by Oliveira et al. 2021 and this manuscript come from Cinthia Oliveira's doctoral thesis and had the support of FACEPE and CNPq.
Reviewer 2 Report
L 27: Give full name prior to acronym for TAGB and TAGC.
Authors define TAGB as above-ground total biomass, then I guess then acronym is AGTB?
Similarly, above-ground total carbon acronym should be AGTC
L137: Do not italic Figure 3
L273: Use number format for citation: R Core Team, 2017
L 296: Check spelling: Figura 4
L 433- 455: Comment not address in the revised manuscript. Generally, A summary paragraph is given for the conclusions beside bullet points.
Author Response
L 27: Give the full name before the acronym for TAGB and TAGC.
Answer: Correction made in the manuscript
The authors define TAGB as total above-ground biomass, so I think the acronym is AGTB?
Likewise, the acronym for total carbon above ground must be AGTC
L137: Non-italic Figure 3
Answer: Correction made in the manuscript
L273: Use number format for quote: R Core Team, 2017
Answer: Correction made in the manuscript
L 296: Check spelling: Figure 4
Answer: Correction made in the manuscript
L 433-455: Comment not addressed in the revised manuscript. Generally, a summary paragraph is provided for the conclusions next to the markers.
Answer: Correction made in the manuscript
