Assessing the Magnitude of the Amazonian Forest Blowdowns and Post-Disturbance Recovery Using Landsat-8 and Time Series of PlanetScope Satellite Constellation Data

Round 1

Reviewer 1 Report

The manuscript explained how Satellite Remote Sensing imagery is used to survey and assess magnitude of Amazonian forest blowdowns and post-disturbance recovery. Non-Photosynthetic Vegetation (NPV), Green Vegetation (GV) and Shade Fractions were calculated for each imagery using Spectral Mixture Analysis. The result indicated the Planet NICFI data provided more accurate characterization of post-disturbance vegetation recovery than Landsat 8 data. But there were still some doubts that need to be clarified:

(1) The first occurrence of "ΔNPV" in the abstract needs an explanation about its meaning. 

(2) In the chapter of "Landsat-8 and Planet NICFI satellite data", it's necesseary to list the data "scene number" used in this research for the convenience of repeatability checkout.

(3) The description were needed to explain the role of "normalization using BRDF-corrected Sentinel-2 data".

(4) How to caculate the abundance fraction using the endmember spectral signature M, which be obtained from reference spectral libraries derived from field or laboratory measurements?

(5) How to obtain  GV value and ΔNPV threshold value?

All in all, The theme of the manuscript is good. It comprehensively assesses the magnitude of the Amazonian forest blowdowns and post-disturbance recovery using Landsat 8 and Planet NICFI satellite imagery. However there is too less description in the manscript. I hope the authors can expound it.

Author Response

Please see the responses in the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

This paper studies the blowdown phenomenon in the Amazon forest, providing an accurate assessment of the damage caused by forest blowdown, and providing the possibility for accurate mapping and statistics.

There are the following issues for reference and modification:

1. In the citation of the paper, it should not only consider the monitoring of the blowdown phenomenon using optical data, but also include research on the blowdown phenomenon using radar data.

2. When comparing landsat8 and NICFI data, the paper only study their differences through gap. You should focus on the impact of spatial resolution and Spectral resolution differences on the blowdown phenomenon, and accurately evaluate its effectiveness. Especially for NICFI data, due to the small number of spectral bands, how to ensure the stability of its extraction from the spectrum.

3. In addition, it should be noted how to accurately identify blowdowns. Not all changes in NPV or GV are caused by blowdowns, and how to distinguish them should be explained.

4. At present, the results discussion section of the paper is too simple, only discussing changes and thresholds, and the significance of the results is limited. It is recommended to combine field sampling data and focus on analyzing the remote sensing image features or various vegetation index features of these blowdown areas, quantifying the changes in blowdown areas, and proposing relevant feature indices that can accurately reflect their changes, similar to those related to vegetation phenology.

5. Meanwhile, due to the damage caused by the blowdown, it is highly recommended to include radar data for comparison. One is that the radar data is not affected by weather images and the temporal data is stable. Additionally, the special structural changes of the blow down can be displayed in the radar data.

Author Response

Please see the responses in the attachment.

Author Response File: Author Response.docx