Clearly - as you note - the individual-tree analysis in (3) [I did not read the others] is not relevant to the point raised by the comment you are addressing. (In turn, that comment/speculation itself is not really relevant to the point above it.)

The above papers seem to be an attempt to answer the question, "Can't we just re-capture the carbon released from deforestation/logging by re-planting small trees in these areas," and the answer seems to be "not on a 1:1 basis".