Hyperspectral Analysis and Regression Modeling of SPAD Measurements in Leaves of Three Mangrove Species

Round 1

Reviewer 1 Report

Dear Sirs,

your manuscript was methodologically well-planned, and the research for a suitable model of SPAD values prediction was properly performed. I only have reservations about its content significance, since both hyperspectral and SPD observations were carried out in the laboratory; it could be a solid background for future hyperspectral data collected by UAVs or satellites, as you yourselves write, but I think the model should be in this case recalibrated.

Some minor flaws are reported in the attached file.

I think your paper need a minor revision, best regards

 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

 Your manuscript requires fixing several issues prior to publication.

 

The most important issue is the term “Chlorophyll content” – although SPAD is correlated to leaves’ chlorophyll content, you do not show any measurement of this parameter. Thus, in order not to mislead the reader, you need to change the text accordingly by exchanging “Chlorophyll content” with “SPAD measurements”. Here are several examples:

·       The title should be changed to “Hyperspectral analysis and regression modeling of SPAD measurements in leaves of three mangrove species”

·       In the Results section 3.1, lines 212-214, you wrote that your findings “indicates that leaves with a higher chlorophyll content also have less discrete SPAD values, and the distribution of chlorophyll content becomes more uniform”.

·     In Conclusions, lines 421-423, you wrote: “The leaves of B. sexangula had lower chlorophyll content than those of C. tagal and R. apiculata. Plants with higher leaf chlorophyll content had less dispersion of chlorophyll content.”

 

Furthermore, when you described the correlation between the SPAD and the chlorophyll content in lines 53-57, you cited 3 papers that test these relationships in rice, wheat, and cotton. Not in forest or orchard trees and especially not in Mangroves. Can you please find at least one paper that justifies these relationships in Mangroves?

 

A different issue is your hyperspectral measurements – looks like your measurements were taken inside a room, utilizing a specific lamp and not direct sunshine. If so, please add this information.  Why I’m guessing it? Because outdoor measurements show atmospheric interference in the range of 1200-1300 and 1800-1900 nm, and most researchers remove the data from this range. Furthermore, your statement that your research “can provide a methodological reference for large-area SPAD prediction at UAV and high-altitude satellite scales” (Lines 336-337) is not accurate because UAV and satellite imagery do use Sunshine with all the problems of atmospheric correction you did not take care. Therefore, this sentence should be rewritten.

 

Section 3.1 – the entire paragraph should be rewritten. The sentences in Lines 205-210 directly describe the values in Table 1, and no new information is added. These can be removed or explained in shorter. What is important in these results are the low values of the Coefficient of Variation, indicating that your measurements are of good quality. Yet, one issue you need to explain to the reader: these results show there is no real difference between the studied species. Why not treat them together? Please explain this issue or present statistical analyses to confirm there is a significant difference, which requires different analyses for each one of these species.

Author Response

Please see the attachment.

Author Response File: Author Response.docx