# Sensitivity of Optical Satellites to Estimate Windthrow Tree-Mortality in a Central Amazon Forest
## 5 Conclusions  
Increasing the spatial resolution of satellite images reduced the uncertainty of estimates of windthrow tree-mortality but did not improve their accuracy. Compared to WorldView 2 and Sentinel 2, Landsat 8 provided more reliable estimates that reflected our field measurements at the individual tree-level. These results highlight the feasibility of Landsat 8 for mapping windthrows and monitoring forest recovery in the Amazon. To fully benefit from high-resolution images, field surveys used for model calibration should account for individual tree-damage (e.g., defoliation, crown breakage, and branch fall). However, high spatial resolution satellite imagery are expensive and restricted to small areas and time periods, which limits their application for large-scale and long-term assessments of mortality and recovery. Future studies applying high spatial resolution imagery could focus on overcoming the limitations of coarser sensors in detecting small clusters of dead trees and quantifying individual tree-damage. This will improve current knowledge on mechanisms and rates of tree mortality, as well as on associated processes regulating forest dynamics and carbon balance in Amazon forests. The following are available online at [[https://www.mdpi.com/article/10.3390/rs15164027/s1](https://www.mdpi.com/article/10.3390/rs15164027/s1)]([https://www.mdpi.com/article/10.3390/rs15164027/s1](https://www.mdpi.com/article/10.3390/rs15164027/s1)), Figure S1. General aspect of the studied windthrown forest, Figure S2. Delimitation of the accessing trails for conducting the forest inventory, Figure S3. Delimitation of the central tracks of the forest inventory plots, Figure S4. General aspect of fallen trees and piled debris in the studied area, Figure S5. GLM models describing the relationship between windthrow tree-mortality measured in the field and estimated using remote sensing data (\(\Delta\)NPV), Figure S6. Distribution of windthrow tree-mortality (%) estimated with \(\Delta\)NPV calculated for Landsat 8 and Sentinel 2, Figure S7. Windthrow tree-mortality measured in the field and estimated using \(\Delta\)NPV calculated for Landsat 8 and Sentinel 2, Figure S8. Analysis routine for selecting endmembers used in Spectral Mixture Analysis and modeling, Figure S9. Spectral signature of the selected endmembers calculated for (a) Landsat 8, (b) Sentinel 2, and (c) WorldView 2, Figure S10. Distribution of NPV values estimated from satellite data with varying spatial resolution (i.e., from 2 m to 30 m pixel), Figure S11. Distribution of NPV values calculated from satellites with varying spatial resolution (from 2 m to 30 m pixel), Table S1. Reference data of tree density in Terra Firme/Campinarana forest in Central Amazon, Table S2. Satellite image collection and specifications, Table S3. Forest inventory and satellite estimates for the field subplots, Table S4. Fitting summary of GLM models used to relate field with remote sensing estimates of windthrow tree-mortality using \(\Delta\)NPV for Landsat 8 and Sentinel 2 in a Central Amazon forest, Brazil, Table S5. Descriptive statistics for windthrow tree-mortality (%) measured in the field and from \(\Delta\)NPV values calculated for Landsat 8 and Sentinel 2 for a Central Amazon forest, Brazil, Table S6. Forest inventory and satellite estimates of windthrow tree-mortality using \(\Delta\)NPV values calculated for Landsat 8 and Sentinel 2 at the subplot level. [PERSON], R.I.N.-J. and [PERSON] planned and designed the research; R.I.N.-J. and D.M.M. collected field data; [PERSON] carried data analyzes with support from R.I.N.-J., J.d.S., A.J.N.L., J.Q.C., S.T. and D.M.M. ; [PERSON] and [PERSON] wrote the manuscript with the support from all authors. All authors have read and agreed to the published version of the manuscript. This research is part of the INVENTA (Interacao Vento-Arvore na Amazonia), and the ATTO projects funded by the German Federal Ministry of Education and Research (BMBF contracts no. 01 LB1001A and no.