"Caliper" means the standard for trunk diameter measurement of nursery stock. Caliper of the trunk shall be the trunk diameter measured at DBH (Diameter at Breast Height), which is defined as four feet, six inches (4.5 feet) above the grade around the base of the tree trunk. (Added by Amended Ord. 08-101, Jan. 21, 2009, Eff date Apr. 21, 2009).