Vegetation drives the carbon cycle between the atmosphere and the land surface by photosynthesis and respiration, and storing the carbon as biomass. Because the carbon cycle dominates the concentration of atmospheric CO2, the most essential greenhouse gas, the investigation of the carbon stock stored as the biomass over extensive geographical regions is important for climate change studies.

This study made an attempt to develop an estimation algorithm of the forest above-ground biomass (FAGB) by PALSAR of ALOS, targeting forests in the south-north transect from the boreal forest to tundra in Alaska. First, 20 PALSAR scenes in summer of 2007 were collected, then, this study develops a simple approach to reduce so-called “slope-effect” by calculating a combination of back scatter intensities in HV and HH modes. Next, the FAGB estimation algorithm was parameterized by the in-situ FAGBs at 29 forests that were acquired by ground-based survey in July 2007. Finally, the slope-effect reduced FAGB mapping was done. Generally, it was found that there is a south to north gradient in FAGB that reflects the vegetation biomass gradient from southern forest-rich region to northern forest-sparse region in the ecotone. The FAGB in some southern regions reaches 100 Mg/ha.