C-BAND INTENSITY-BASED GROWING STOCK VOLUME ESTIMATES VERSUS THE MODIS VEGETATION CONTINUOUS FIELDS TREE CANOPY COVER : DOES C-BAND SEE MORE THAN CANOPY COVER ?

In [1] the validation of a novel algorithm for the retrieval of boreal forest growing stock volume, GSV, with multi-temporal stacks of ENVISAT ASAR C-band intensity data was presented. The high retrieval accuracies that were reported contradicted the widely accepted notion that C-band is not suited for GSV retrieval since the signal hardly penetrates into the canopies and rather reflects the horizontal structure of forests, e.g. the canopy cover, than their threedimensional structural properties. In this paper we aim at providing evidence of the capability of C-band to sense the vertical structure by comparing the GSV maps that were produced for Central Siberia and Sweden with the MODIS Vegetation Continuous Field canopy cover product [2]. The comparison with reference GSV data showed that canopy cover is a major predictor for GSV up to the point of canopy closure, which was reached at the validation sites at ~200 m/ha. The GSV maps produced with ENVISAT ASAR data showed a clear sensitivity to GSV differences beyond canopy closure, suggesting that C-band senses more than just canopy cover but also the vertical forest structure.

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