DBH (Diameter at Breast Height) is a measurement of a tree's trunk diameter taken at approximately 4.5 feet (1.37 meters) above the ground. It is commonly used in forestry and arboriculture for assessing tree size and growth. Tree age and DBH are related because you can estimate a tree's age using its DBH and the growth factor specific to its species. The formula is: Tree Age = DBH / Growth Factor This estimation provides a rough idea of a tree's age based on its diameter.