Well, actually they do, but after a bit more googling they're not net carbon emitters, and old forests apparently still can capture net carbon. So my point isn'

Well, actually they do, but after a bit more googling they're not net carbon emitters, and old forests apparently still can capture net carbon. So my point isn't as strong as I thought it was. Trees take in CO2 due to photosynthesis, but they also respirate, taking in O2 and emitting CO2. The net amount of CO2 taken in decreases as the tree ages... so young forests do take in more CO2, but old trees still usually take in slightly more CO2 on the net, due to repairing themselves.