Modelling the Dynamics of Carbon Storages for Pinus densata Using Landsat Images in Shangri-La Considering Topographic Factors
Round 1
Reviewer 1 Report
In the paper entitled: “Modelling the dynamics of carbon storages for Pinus densata using Landsat images in Shangri-La City considering topo-graphic factors”, Landsat 5 and 8 data are used to estimate the carbon stocked by P. densata over time. The study area is Shangri-La in southwestern of China. Although the work seems carefully developed, there are some critical issues that need to be attentively clarified.
I would ask you to answer the questions carefully and make appropriate changes. In case I misunderstood some aspects I would ask for careful review to edit and clarify.
The results and discussions have not yet been properly revised due to the many requests in the methodological part. I would ask to review them independently given the changes made
General considerations
Prefer to use t ha-1 instead of t/ha
In this study is quite abused at the beginning of several sections.
Specific requests
Abstract: please make short sentences. Avoid the repeated use of semicolon
Line 17. Consider to change extracted
Lines 26-27. consider to remove “to a certain extent”
Lines 27-28. Are these statistics the average for the three models considered?
Keyword. consider to change acronym TNI, with full name
Introduction
Lines 44-45 consider to present the changing of CO2 ppm
Line 45 GHG are all part of global warming, please start from the general aspect and after that focus on CO2
Line 61. The development of a model is not a simulation. Remote sensing variables are the covariate of a model to evaluate a dependent variable (such as carbon stock). Please be more precise in this statement.
Lines 64-65. Usually the model already available are used in remote sensing field. Change the word developed.
Lines 69-70. Add some accuracy evaluation to support the research of Gomez and Zhang.
Lines 104-105 is the study carried out in Shangri-La or is it correct Shangri-La City?
Lines 106 the “different kinds of change data” are not clearly presented in the introduction.
Materials and Methods
Consider to add a flowchart image to better understand the analysis and the difference between yearly and 5 years change.
Figure 1. Please, provide some change in plots colour or dimension (maybe related to survey year). Consider to add a forest mask or map highlight the relevance of forest in the study area. Moreover, add the scale in the Part of terrain
Lines 126-128. The sentence is clear but consider to revers it. Consider to present the total amount of NFI plot available and after that state that the study focus on P. densata (presented as main species in 136 plot).
Lines 134-137. Is it a common way to calculate AGB in China? Why do not use the single tree dimension for calculate AGB of each tree and then sum all?
Lines 140-142. Please in the discussion introduce some statement about the value of removed outlier plots.
Lines 155-156. It is superfluous present the values reported in the traditional boxplot.
Line 157. Consider to add the “maximum annual mean” and so on.
Figure 2. Rephrase the caption, add the word: boxplot, year.
Lines164-170. The paragraph is acceptable. Otherwise, consider the numerous approaches to create a cloud free composite (BAP, medoid, C2C, From the Canadian White et al. Hermosilla et al).
Paragraph 2.3.2 instead of extract, consider to present the evaluation of indices per pixel. Moreover, in the study are used images from Landsat 5 and 8 and the bands numbers are not coincident. For clarity you may stated that the equations are evaluated considering the band names of Landsat 8 and the closer wavelength of Landsat 5.
Lines 187-193. The statements are incorrect. Please read carefully reference [35] to better understand the texture feature meaning. You calculate indices.
Lines 235-237. The statement is correct, however, it is necessary to have reference data close in time to provide accurate estimates of the process of change.
Lines 242-243. Please rephrase.
Lines 244. Are the 244 indices the total considering all the year? So, you do not consider the same index per year. Is it correct?
Line 246. Which package or function implementing RF are used?
Lines 293-297. Was the effect of TNI evaluated by including it among the predictors of the models, without changing other predictors?
Line 301. Is CV provided in the 70%?
Accuracy evaluation. Considering equation 6, you evaluate the average annual change. Which yi are considered for the accuracy evaluation? Please
Results
366. is it not decreasing also in period 2012-2017?
Figure 3. Consider to putt in different bars each indicator
Consider to change the order of Figures 6 and 7.
Author Response
请参阅附件。
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript addresses the estimation of changes in forest carbon stocks using satellite remote sensing data. Carbon stock changes can help to estimate the carbon sink of forests, so this research meets a recent societal demand regarding climate change. I believe this manuscript is worth publishing, but recommend the following minor revisions.
1. [lines 65-67] It is difficult to understand what is means of "static model" and "dynamic model" in this sentence. Since these are important concepts in this study, please explain them clearly here.
2. [line 121] Please describe whether the Pinus densata, targeted in this study, is artificial or natural forests.
3. [lines 128-129] I felt curious as to why the number of NFI sample plots varied from year to year. Please explain the reason for this, along with whether the NFI adopts permanent sample plots.
4. [lines 139-140] Please describe the respective units of AGB, DBH, and H.
5. [line 152] Similarly, please describe the respective units of CS and AGB.
6. [line 159 & Figure 2] I think the unit of carbon storage should be "t-C/ha" to distinguish it from AGB.
7. [lines 200-202] The algorithms used in this study (PLSR, GBRT, RF) require multiple input parameters. Why did the authors adopt the parameter TNI, instead of two input parameters, elevation and slope? Please describe the reason for adopting TNI.
8. [lines 229-230] There seem to be some missing sample plots depending on the year (line 129), and please describe how to deal with them.
9. [lines 300-302] Please describe the specific number of data used for model fitting and validation.
10. [Table 4] It is difficult for the reader to know whether these RMSEs and MAEs are large or small. For example, please include the %RMSE, or the average values of the 5-year interval change and annual average change (perhaps in the main text). By the way, is "5a" a typo for "5-year"?
11. [section 3.2] When creating the carbon storage maps, how was the distribution area of Pinus densata identified? Also, what is the spatial resolution of these maps? Please describe them.
12. [Figure 5] Usually a scatter-plot should include 1:1 line. I guess this is a fitted line to the plots. Please show a 1:1 line.
13. [lines 420-423] According to the description in section 3.2, I guess that the authors could easily compare and validate the dynamic model and the static model in this study as well. Why was this not conducted?
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The second version of the paper seems more accurate. The authors have made an effort to address the various queries with additions and changes to clarify some doubtful points.
Methodological choices have been clarified overall. However, some parts of the text are redundant. For some clarifications a few words may be enough. E.g., lines 73-75 the readers of the journal know what is remote sensing and how it is commonly used.
Line 229 change with The remote sensing pixel values.
Line 306 is a correct concept (also correct in grammar) but please rephrase it. The sentence is not structured as required by academic English.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
