Age ≈ DBH (inches) × Species Growth Factor
Tree age can be estimated by multiplying DBH (diameter at 4.5 ft height) by a species growth factor. Fast-growing trees (cottonwood, silver maple) have low factors (2.0); slow-growing trees (white oak, sugar maple) have high factors (4.5-5.0). This is an approximation — actual growth varies with site conditions, competition, and climate. More accurate methods: increment corer (extracts a pencil-thin core showing annual rings), ring counting on a stump, or historical records. The oldest known trees are bristlecone pines exceeding 5,000 years. Annual ring width varies with climate, making dendrochronology (tree-ring dating) a powerful tool for reconstructing historical climate.