Testing TerraSAR-X for forest disturbance mapping. Research Report for the German Aerospace Center (DLR)

This is the final report on the testing of the free science data provided by DLR for application LAN_0101. The idea was to test TerraSAR-X data for forest monitoring, with a particular focus on interferometric processing for forest disturbance monitoring. With disturbance is here meant damage such as insect defoliation or whole tree removal by storm or tree harvesting. It turned out that coherence is a promising tool for detecting and monitoring low biomass stands, in particular clear cuts. Coherence derived from the Tandem-X mission might be a valuable supplement to InSAR processing and the use of InSAR height. A number of key forest variables, including tree height, biomass and stem volume, are strongly correlated to InSAR height. This SAR variable represents the height of the RADAR echo above ground and is derived as the difference between an InSAR DEM and a DTM. InSAR height is promising for forest monitoring, however, a possible problem is that the accuracy in low biomass forests might be low due to inaccuracies in the DTM and DEM. Hence, coherence which is particularly effective on the low-biomass stands might be a valuable auxiliary data set forest monitoring.