Disclaimer: this may be specific to forests in British Columbia. It's actually quite complicated; the way harvesting work doesn't nicely mimic how trees natura

Disclaimer: this may be specific to forests in British Columbia. It's actually quite complicated; the way harvesting work doesn't nicely mimic how trees naturally die and are replaced in the forest. So if you harvest with clearcuts or even selective logging and don't replant, you'll probably end up with a different forest composition than if natural methods (fires/pests/rot) had removed those trees. So replanting is done to try and correct that imbalance and get the forest back into a healthy functioning state as soon as possible. It's also much faster than allowing natural regrowth - especially in a clear cut area. If you replant you can also use improved (through breeding, not GMO at this point) plant stock, so you'll end up with better yields in ~80 years.