Every person who shall, within any of the fire towns or within any fire district or part thereof when so designated by department regulation, fell or cause to be felled or permit to be felled any evergreen tree for sale or other purposes or engage in salvaging any blown down evergreen tree shall cut off or cause to be cut off from the tree at the time of felling or salvaging the tree, unless otherwise authorized by the department before the trees are felled or salvaged, all the limbs thereof up to a point where the trunk of the tree has a longest diameter which does not exceed three inches, unless the tree be felled or salvaged for use with the limbs thereon.