Actually, it's known land use change AND
In other words, all the trees are included. What's not included is the 'net carbon flux estimates from non-forest soils'. You're not really claiming this could bridge the gap, are you? Keep in mind that the USA only has a very tiny portion of the world's land and trees, while we generate a disproportionately large amount of CO2. Toss in Canada, and look at North America as a whole, and maybe the net CO2 emissions offset by sinks won't look quite as bad!