Deforestation in the Brazilian Amazon fell by 77 percent from 2004 to 2011, but carbon emissions did not drop as steeply because of complex processes revealed during on-the-ground studies, scientists say. While analysis of satellite images showed the three-quarters drop in deforestation, researchers said that several factors — including the slow decay of roots and the later burning of wood biomass — meant that carbon emissions from deforestation fell by 57 percent during the same period, according to a study published in the journal Global Change Biology. Another reason for the 20-percent lag in carbon emissions reductions is that logging in recent years has been moving into denser Amazon forests, so even the reduced amount of deforestation is leading to higher carbon emissions, researchers said. U.S. scientists praised their Brazilian colleagues for the sophisticated new techniques used to tease out the differences between reduced deforestation and lagging emissions reductions. “That’s where you’d like the rest of the world to be, where Brazil is,” said Richard Houghton of the Woods Hole Research Center.