|Title||TanDEM-X elevation model data for canopy height and aboveground biomass retrieval in a tropical peat swamp forest|
|Author(s)||Schlund, Michael; Poncet, Felicitas von; Kuntz, Steffen; Boehm, Hans Dieter Viktor; Hoekman, Dirk H.; Schmullius, Christiane|
|Source||International Journal of Remote Sensing 37 (2016)21. - ISSN 0143-1161 - p. 5021 - 5044.|
Earth System Science
|Publication type||Refereed Article in a scientific journal|
It was demonstrated in the past that radar data is useful to estimate aboveground biomass due to their interferometric capability. Therefore, the potential of a globally available TanDEM-X digital elevation model (DEM) was investigated for aboveground biomass estimation via canopy height models (CHMs) in a tropical peat swamp forest. However, CHMs based on X-band interferometers usually require external terrain models. High accurate terrain models are not available on global scale. Therefore, an approach exclusively based on TanDEM-X and the decrease of accuracy compared to an approach utilizing a high accurate terrain model is assessed. In addition, the potential of X-band interferometric heights in tropical forests needs to be evaluated. Therefore, two CHMs were derived from an intermediate TanDEM-X DEM (iDEM; as a precursor for WorldDEMTM) alone and in combination with lidar measurements used as terrain model. The analysis showed high accuracies (root mean square error [RMSE] = 5 m) for CHMs based on iDEM and reliable estimation of aboveground biomass. The iDEM CHM, exclusively based on TanDEM-X, achieved a poor R2 of 0.2, nonetheless resulted in a cross-validated RMSE of 54 t ha−1 (16%). The low R2 suggested that the X-band height alone was not sufficient to estimate an accurate CHM, and thus the need for external terrain models was confirmed. A CHM retrieved from the difference of iDEM and an accurate lidar terrain model achieved a considerably higher correlation with aboveground biomass (R2 = 0.68) and low cross-validated RMSE of 24.5 t ha−1 (7.5%). This was higher or comparable to other aboveground biomass estimations in tropical peat swamp forests. The potential of X-band interferometric heights for CHM and biomass estimation was thus confirmed in tropical forest in addition to existing knowledge in boreal forests.