Disentangling Soil, Shade, and Tree Canopy Contributions to Mixed Satellite Vegetation Indices in a Sparse Dry Forest
Round 1
Reviewer 1 Report
General comments
I have been invited to review this paper by Wang et al. The paper aims to quantify the fractional contributions of each surface component (soil, shade, canopy) in the mixed pixels, and to develop a new approach to calculate the actual canopy NDVI from mixed satellite data. Generally, the manuscript is well-written, and the used English language level is more than satisfactory. However, some points need to be considered and revised. The overarching aim of the study needs to be clearly mentioned within the last paragraph of the introduction. Furthermore, some sections in the results and discussions should be moved to other sections. Lastly, a “conclusions” section is missing and needs to be added. Please see my specific comments below:
Specific comments
Abstract
Line 9: “Yatir forest”. Where is this forest located? Needs to be mentioned in the abstract, particularly since it was not mentioned in the title.
Line 11: “NIR” needs to be spelt out explicitly.
Line 13: “UAV” needs to be spelt out explicitly.
Line 17: “NDVI” needs to be spelt out explicitly.
Introduction
Lines 62-63: Ref(s) needed.
Lines 64-65: Ref(s) needed.
Lines 66-69: Ref(s) needed, and by the way, this is a lengthy sentence that needs to be shortened.
Lines 77-80: Ref(s) needed.
Line 87: “the objectives of this paper/study were to”
Lines 87-90: OK, these are the objectives. What is the overarching aim of your study?
Materials and Methods
Line 100: “LAI” needs to be spelt out explicitly.
Lines 113-114: “the 2010”. Remove “the”.
Line 119: Figure 1: A new window needs to be added (e.g., d) to present the location of this study area relative to the country’s map.
Results
Line 266: “m2”.
Lines 277-278: “The canopy NDVI values were the highest”.
Line 278: “while the soil NDVI values were the lowest”.
Line 321: Section 3.5: Most of this section should be presented within the methods section.
Line 370: Figure 8: “2013-2019”. Is it 2019 or 2018?
Discussion
Lines 405-416: This section can be considered a conclusion rather than a discussion.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This paper investigated the relationship between field-measured canopy NDVI and Landsat 8 measured NDVI and tried to disentangle the contributions to satellite NDVI from soil, shade, and tree canopy. However, it is unclear how this research could help unravel the canopy NDVI from Landsat NDVI on large spatial scales. The manuscript was not clearly and coherently written. The authors should address the following detailed comments before the manuscript be published.
l In the abstract, please write the full name of NIR, UAV, and NDVI when they first appear in the manuscript.
l Line 89: How do the authors define “canopy NDVI?”
l Figure 1: How did the authors locate the boundaries of Landsat pixels?
l Section 2.2.2: the view geometries of the tower sensor and Landsat OLI sensor are very different—how do the authors consider the discrepancy of the sun-view geometry for the two sensors. In addition, the NIR spectral bands for the tower sensor and OLI are different; could this also contribute to the discrepancy between Landsat and tower NDVI?
l Section 2.2.3, the NIR band setting of the UAV sensor is different from those of the tower sensor and OLI; could the authors discuss this issue in the paper?
l Line 163: could the authors elaborate on “complex processing?”
l Line 177: “Geographical”—the first letter doesn’t need to be capitalized.
l Equation 1: how did the authors get the parameter of 1.5?
l Equation 2: could the authors validate that this equation also fits the study area?
l Equation 3: how did the authors co-allocate the Landsat pixel and the UAV image?
l Section 2.4: when simulating the forests, how did the authors simulate the distribution of trees in the scene?
l Lines 226-228: these lines from the template should be deleted.
l Figure 2: the data derived from Landsat and the tower sensor were very different, and this is expected because of the different spectral band settings and view geometries. What is the purpose of including this figure in the paper?
l Figure 3: how did the authors locate the Landsat pixel?
l Figure 4: what’s the reason for the variation?
l In Figure 6, the inconsistency between Landsat 8 and UAV at the NIR band could be due to different spectral band response functions. Could the authors consult related literature and discuss this issue in the Discussion section?
l Section 4: please set a few sub-headings.
l There should be a Conclusion section.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
V
The present manuscript "Disentangling soil, shade, and tree canopy contributions to mixed satellite vegetation indices in a sparse dry forest" by Wang et al. is an interesting study presenting a procedure that aims to improve the canopy NDVI by using mixed satellite data. The topic is in line with the scope of Remote Sensing. I have just some comments and suggestions for the authors.
The introduction is clear and presents the state of the art of the topic but misses to highlight the importance of applying this procedure in a broader context. Who can have an advantage from these findings? In which fields can be used? I suggest adding a paragraph that highlights the importance of the present study for a wider audience.
Lines 66-69: Please, rewrite this sentence and make it clearer and more fluent.
Lines 81-83: The last part of the sentence is not clear
Line 101: Please move “mean” before “annual”
Line 109: Rendzina is a well-known soil type, however, you have to add the reference to the soil classification system. What do you mean by “light Rendzina”?
Line 209: the sensor “is/was” located…
Results
Lines 226-228: I suggest deleting this part, it is a too general sentence
Line 280: The meaning of the following sentence is not clear: “…presumably due to the appearance of annuals that enhanced the soil NDVI”.
The following sentences sound more like a discussion and the author’s opinion than a simple result: Lines 235-236; 255-257; line 280; lines 291-294; lines 310-313
Discussion
Lines 430-434: These sentences sound more like a simple presentation of the results than a real discussion; please, could you better discuss the meaning of your results?
Line 468: “short season annual”?
Lines 468-473: Most likely it's just my misunderstanding: what do you mean by "annual" in this context?
Conclusions are missing: I suggest to resume your main findings in the conclusive part, with also an indication of the rationale of your study.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I would like to thank the authors for considering my comments and suggestions. The current version of the paper is now significantly improved over the previous one.
Line 135: Figure 1: I can see two figures labelled as figure 1. Looks like they are both the old and the new figures, consider removing the old one.
Author Response
Line 135: Figure 1: I can see two figures labeled as figure 1. Looks like they are both the old and the new figures, consider removing the old one.
Response: Done.
Reviewer 2 Report
The authors did not address the reviewer's concerns appropriately and sufficiently but reiterated their arguments. They did not take the previous review seriously.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
