Potential of TerraSAR-X and Sentinel 1 imagery to map deforested areas and derive degradation status in complex rain forests of Ecuador

Abstract

This study explores the use of TerraSAR-X (X-Band) and Sentinel-1 (C-Band) SAR data for detecting degraded forests and deforestation in the Sumaco Biosphere Reserve, Ecuador. The study area shows a complex topography and permanent cloud cover, which complicates forest monitoring from optical remote sensing. Thresholds of canopy cover for degraded forest were identified by field data. Then a straightforward object-based approach was applied. Statistics on SAR backscatter were estimated from the objects and used as input to a random forest classification to map forest and non-forest areas. Finally, forest degradation was assessed using a moving window procedure applying the earlier identified thresholds on the forest / non-forest map. The SAR data were found adequate to map deforestation (overall accuracy of 81% for forest/non forest maps) but less accurate to fully assess forest degradation. However, multi-temporal SAR data can be useful to construct baseline data of the forest extent. Polarization and interferometric information could enhance the presented results for classifying forest / non forest areas and mapping forest degradation.