www.co2science.org/script...5/EDIT.jsp
www.co2science.org/script.../N5/C3.jsp
www.sciencemag.org/cgi/co...2/5388/386
Here's few references that seem to indicate that the forests of North America consume more CO2 than is produced in North America making us a net CONSUMER of CO2.
Some of this CO2 would be lost back to the atmosphere to burning, natural decomposition etc. I seem to recall that younger trees sequester more CO2 than old growth trees. Since old growth forests are also more susceptible to forest fires it would make sense from a CO2 balance sheet point of view for forest companies to increase logging and reforestation intensity. This would serve to more permanently lock CO2 into building materials etc rather than risk have them released into the atmosphere by fire.
Personally I don't think CO2 concentrations really have anything to do with global warming to any significant amount. A look at past CO2 concentrations seem to indicate that global warming causes increases in CO2 rather than the other way around.
www.wcel.org/wcelpub/2000/13090.pdf
Of course some enviro weenies don't like the idea of deforesting old growth forests as in the link above. Basically they don't want to lose their old growth forests due to something (Kyoto) they have argued for. Kyoto in fact only credits forest sequestration for forest that has been planted since 1990 thus taking out of the equation existing forests. (I think Canada was arguing that we should be given credit for trees planted where logging had occurred).
I also seem to remember reading somewhere that the amount of CO2 sequestered in peatlands was fairly significant too.
I should add that with global warming forests are moving north increasing the size of the forests and the amount of CO2 being absorbed. So global warming and increased CO2 levels are good for forests.