Yes, it could capture more carbon, but the carbon is lost, whereas the carbon stored in the forest stays there. Also, because of the longevity of the trees, they also enhance carbon sequestration below ground, whereas corn.... I'm not a big fan of removing agriculture residue for energy production, because we need a certain degree of organic matter to go back into the agricultural lands to maintain the soil organic carbon level and the organic matter, but only part of that carbon goes into the grain, and then the grain is consumed. If the rest of the residue is removed from the field, then there's no net accumulation over a period of time.
On December 7th, 2017. See this statement in context.