Mapping Floristic Composition Using Sentinel-2A and a Case Study Evaluation of Its Application in Elephant Movement Ecology in Sagalla, Kenya

Round 1

Reviewer 1 Report

The manuscript by Mugo et al. presents an investigation using Sentinel-2 data to classify vegetation cover in an area in Kenya which exhibits conflicts between (raiding) elephants and humans. The investigation aims at identifying connections between vegetation cover and its location and elephant movement.  

In general, the manuscript demonstrates that quite some work has gone into the research and it provides good ideas and interesting implications. It is certainly not cthe most innovative approach when it comes to image anaysis but that does not reduce its value. However, I say 'interesting' as the actual relevance remains a bit unclear to me. I understand that raiding elephants are not a good idea in no village or settlement. But the authors unfortunately do not document what the actual impact is, in terms of financial loss, damage or other effects. Also unfortunate, they to do not put their investigation into a larger context and describe the problematic phenomenon on a larger scale. So, while the introduction reads very well, it misses two points: how much damage is caused how frequently, and how large is the problem in Kenya or on a larger scale? This would put at least some price tag to the topic of relevance.  

Also, what has been done in this domain of investigations? A short review would certainly help.

Secondly, while the text is generally well written except for a few odd sentences or colloquial statements ("deforestation contributed to climate change", "This process was both expensive and consumed a lot of time"), it is very convoluted. I mean, 39 pages for basic image classification and correlation is a bit overwhelming in any case. What is more problematic is that the results presentation is extremely organic and switches between results, discussion, interpretation and anecdotes (see. e.g., l613++). I would suggest to clean up the whole presentation, not only text-wise but also with respect to figures. Not because a figure can be included means it has to be included. There are, in my opinion, too many figures documenting similar, or marginally supplementary information, while the main results -- the maps -- are of low quality and do not provide much insights as their design blocks their exploration.  

Thirdly, I believe the abstract can be shortened. It contains relevant material and is well written, but it seems a bit too overloaded with background.  

Also, I might have missed that point, but is there a reason why you did not perform a PCA to reduce correlation effects between bands? Much of your discussion focuses on interband correlation, yet a PCA could solve some headache (e.g., l.458) and reduce complexity.  

The presentation evolves quite a bit around abstract vegetation IDs and comparisons based on these IDs. This gets more complicated further down in the results presentation and discussion. Figures/tables become quite abstract. I believe that with a bit of a cleaner concept, lots of confusion can be reduced in the presentation.  

For the conclusions I would suggest to put this whole research exercise into a larger context. Again, it is about relevance (see above) but also implications for further research and in how far these research results can be transferred to other locations suffering from similar issues.  

Some specific questions:  

"buffer zones where elephants reside is a significant challenge for conservation planning" -- why is that the case? If you could highlight exactly these kind of issues, the relevance would become clearer.  

What is the difference between aim (i) and (iii)? Approaches are different but results seem the same to me?  
"i) determine the natural vegetation species communities and their concentrations in the resulting classification classes, ... , and iii) map these vegetation communities based on their floristic associations.  

Figure 1 needs some improvement, tracks are not visible, it's just a blob of lines, the association between sub-maps is unclear. Also, is the legend correct? Settlements (pink) are in the mountains? The figure with tracks is actually quite relevant though it does not contain vegetation cover. The overview figure is too wide to associate tracks with land cover... and the partial country map only gives very limited information about the location of the study area.  Perhaps this map can be improved by separating information and by generalising?  Also  you might want to check the last figure regarding the same issues.

I suggest to explain this exact process a bit more in detail:  
"We developed comparisons between Landsat 8 and Sentinel 2A band resolutions to define suitable feature identification composite band combinations as illustrated:"  

Figure 2 shows image classification as first step without actually describing its purpose. That is for the removal of atmospheric effects?  

The concept of Importance Value Index (VI) comes from where?

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

General comments

The paper is well written, provides the necessary background information and stepwise introduces the new approach. Furthermore, the methodology is sound. However, there are some improvements that should be made.

The main focus of the manuscript is the mapping of floristic composition based on Sentinel-2A data. In fact, the approach to this topic is more in-depth compared to the analysis made of the relation between the elephant movement and presence and the plant communities present.

Also, in the material and methods section, with the exception of the elephant tracking data collection, only the methodology used to process data and classify vegetation is presented with no mention of the methodology used to establish a correlation between elephant tracking data and vegetation communities or plant species.

Specific comments

Figure 6 and Figure 7 - The present figures are negatives (inverted, with black as the background). Please consider eliminating Figure 7 which is not necessary. Figure 6 has all the information needed.

Line 715 - The page numeration has a break on page 23.

Table 3 - Lack of legend for the symbols showing the time of the day of the elephant’s presence.

Line 738 to 749 - Consider including this text in the introduction section.

Line 759 - Repetition of the word “size”.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The present research paper contributes with analysis and methods to mapping the vegetation communities and composition, determining the natural vegetation species,  their concentrations in the resulting classification classes, investigating if these vegetation communities’ locations have any significance to the elephants moving, and mapping these vegetation communities based on their floristic.

I have the following comments and suggestions for including information and improvements.

Abstract

I suggest the authors add more information and details about the methods and results found. The current abstract does not contain information on this aspect, making it a fragile abstract.

Keywords: I suggest that authors include keywords not already contained in the title. This may help readers locate this article more efficiently as it has a broader range of search terms.

Introduction

The authors should illustrate more about the state of the art between lines 81 – 110, and more citations should be included.

A more explicit justification must be included regarding the importance of studying in different locations and counties. This information is essential to give a more general aspect to the study, helping it not appear that the results are only of local importance.

Another critical point that will bring more information to the reader is to describe directly and with greater clarity the objectives of the work. Of course, when reading the complete introduction, we know what the objective is. However, making it more explicit will help readers understand the work's importance.

Methods  

More details must be included in Figure 2, and all tables cited in terms of presentation and details.

Results

Figures (3, 4, 5, 6, 7, 8, 10, 11, 12, 13, and 14) need more details in terms of presentation. All figures cited above need clarity in terms of their description.

In figure 3, it is necessary to include the legend of the y-axis right side. In addition, it is necessary to put more details in the figure caption.

Please replace it with one with a better resolution Figures (3, 10, 11, 12, and 13) in the available pdf show poor image resolution and distortion.

Figure 5 must be a table to communicate all information better.

In Figures (4, 9, 10, 11, 12), I suggest using the same package ggplot2 in R.

Disscution

Citations that give conceptual support to the results found in this section must be included. It is also imperative that the authors include a topic that compares the results found from the methods and analyses proposed in the article with the literature results.

Conclusions

Although the Conclusions section is not mandatory in this Journal, I suggest that authors include this field. Conclusion inclusion will help readers obtain information more synthetically about the main results of the work and their possible applications. In this section, I suggest that information be added about future advances in this field of research, based on the results found in this article.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I thank the authors for their constructive feedback and for incorporating many suggested changes.

I do see that aims are now expressed more clearly, there is now some more background regarding the actual problem this phenomenon causes in communities, and figures/descriptions have been cleaned up as well. The conclusion now also manages to highlight the importance of this research.  Also, the intention behind keeping the original Sentinel bands, rather than performing a PCA, has been made clear, thank you. With that, all my major issues have been addressed.

The authors also introduced new maps and revisited diagrams which resulted in a clear improvement. I further believe that the removal of some of the more confusing figures has helped to clean up the overall manuscript, while the appendix helped to reduce the manuscript's length which makes it more accessible to a wider readership.

However, I still believe this work has a bit of an excessive length and is convoluted in its result description, but I am also convinced it will serve as a transparent and hopefully often-cited basis for future research in this field.  I have no further objection and would recommend publication.

Author Response

Please see the attachment

Author Response File: Author Response.docx