This zone is 50' in distance. It begins at the edge of Zone 1 and extends outward on a horizontal plain. In this area ALL mature trees shall be limbed up off the ground by this rule: If the tree is over 18' in height then limb up lower branches by a minimum of 6'. If the tree is less than 18' in height limb the lower branches up off the ground by 1/3 tree height. Remove all combustible vegetation under the tree drip line of the tree canopy.