How to reduce greenhouse gases emissions from deforestation and forest degradation? This is the heart of the REDD mechanism, launched by the United Nations in 2005. CAP conseil takes part to the EO4REDD research project financed by the Walloon Region. Our aim is to develop a remote-sensing based methodology allowing to estimate forest carbon stocks in tropical areas. The test zone is Mai Ndombe, in the East of the Democratic republic of Congo.