You do not need to deforest a forest to harvest trees. Assuming an annual growth of X m³ha-¹ you'll be able to harvest X*area by taking only mature trees. If you start out from a clear cut or a forested area grown from a recent clear cut you'll need to stagger the first few harvests (which will produce less wood that projected) to create more diversified age strata but once you have this system going you'll be able to keep on harvesting without breaking the forest cover. The effect of such a management technique is not too different from the way trees naturally age and die, especially not when tree crowns and branches (which used to be of little to no commercial value although this has changed with the increased demand for biomass for heating purposes) are left in the forest to make sure the soil is not depleted.