Yes, it's good that we're planting trees but something to keep in mind is that photosynthesis (the reaction that consumes CO2 and produces O2) occurs in the leaves so older, more mature trees consume more CO2 and product more oxygen than younger trees. Even with replanting, the cutting of old growth trees and rain forests results in a net loss in CO2 capture and conversion to O2 unless your replanting significantly more trees than you're cutting. This also ignores the loss of undergrowth associated with logging.

I'm not saying we need to stop all logging, just pointing out that it's not as straightforward as it seems on initial inspection.