"We are all poets when we are in the pine woods," according to Henry Wadsworth Longfellow. Pine trees (Pinus spp.) please the senses with their majestic trunks, their refreshing fragrance and the music of the wind sifting through their needles. You can approximate the age of your favorite pine by applying a simple formula to its measurements.
A good argument can be made that the pine is the best of trees. Pine needles contain fragrant oils that create their distinctive and pleasant smell. Most species grow edible seeds beloved by birds and small mammals. Pines represent longevity in many parts of the Far East and were said to be sacred to Zeus. In modern day, pines grow in U.S. Department of Agriculture plant hardiness zones 3 through 9.
Although hundreds of species of pines exist, most are imposing, erect trees that live more than a century. Some live far longer, like intermountain bristleconepine (Pinus lonaeva) that can survive more than 4,000 years. Pines are evergreen and monoecious, which means that they bear both male and female cones. Pinus is the only genus to have pairs of uncovered seeds on the bracts of cones and bundles of needles with a sheath at the base.
To figure out your pine's approximate age, you need to measure its circumference at chest height, about 54 inches from the ground. Calculate the diameter by dividing the circumference measurement by 3.14, also termed pi. Next, multiply the diameter in inches by the tree's growth factor, a number that has been calculated by arborists through growth ring measurements to reflect that rate of the tree's growth. The growth factor for pines varies among the species. According to the Missouri Department of Conservation, the growth factor for an Austrian pine (Pinus nigra) is 4.5. It is 5 for a white pine (Pinus strobus) and 3.5 for a Scotch pine (Pinus sylvestris).
Applying the Formula
Using the formula, if the circumference of your tree 54 inches above the ground is 31.4 inches, the diameter is the product of 31.4 divided by 3.14, or 10 inches. If the tree is an Austrian pine, its age is about 45 years (10 inches times the growth factor of 4.5.) Austrian pines survive in USDA hardiness zones 4 through 8. If your tree is a white pine, it is close to 50 years old and thrives in USDA hardiness zones 3 through 9. Scotch pine trees grow in zones 3 through 8A, and one with a 10-inch diameter would be about 35 years old.
- Missouri Department of Conservation: How Old Is That Tree?
- Arbor Day Foundation: Pine, White -- Pinus Strobus
- The Lovett Pinetum Charitable Foundation: What Are Pine Trees?
- Fine Gardening: Genus Pinus
- Bartlett Tree Experts: Plant Health Care Recommendations for Austrian Pine
- U.S. Forest Service: Pinus Sylvestris -- Scotch Pine
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