> The regular harvesting and clearing of plantations releases stored CO2 back into the atmosphere every 10–20 years. By contrast, natural forests continue to sequester carbon for many decades4. I'm not sure I understand... To me, the only question is, how much CO2 we store per km2 (which might be a higher number for a natural forest). The plantation being cut down and then regrown has 0 net impact, just like trees dy…
Yes, that's correct - that plantation, in itself, has zero net loss of carbon once it regrows.
What you're missing is the activity in the meantime that contributes carbon to other cycles of carbon heat trapping.
So when all is said and done, sure, that forest is back where it was with the same amount of carbon - but the permafrost it helped melt (with accompanying release of methane) is still melted.