How to Determine the Age of a Tree Trunk

The trunk of a tree is the most vital part of a tree’s anatomy. It provides a complete support system from the roots to the tips of the branches, with the utmost dependency on its sturdiness. For anyone that has sought the comforts of a sturdy trunk for resting during a long hike, the importance of tree trunks goes without saying. But have you ever wondered just how old the tree trunk is that you have sat upon? If so, it can easily be determined with a metric tape measure and calculator.

Things You'll Need

• Notepad
• Pencil
• Calculator
• Flexible metric measuring tape

Instructions

1. Take along a notebook, pencil and calculator along with your metric tape measure, when you are assessing the age of a tree trunk. These tools will come in very handy when recording your findings, and calculating the age of the tree trunk.

2. Note whether the tree trunk is situated close to other trees, or set apart from the others. Close proximity of growth would be considered within 20 feet; otherwise the tree is considered standing alone. This does make a difference, and will help to determine the tree trunk’s age. If during its growing years, the tree has had to fight for sunlight amongst the others, the mathematical equation to determine its age will be different than one that has grown without obstacles.

3. Measure the circumference of the tree trunk using a flexible measuring tape. To do this you will need to wrap the measuring tape around the tree trunk, similar to how a seamstress measure’s someone’s waistline. Use the metric side of the tape measure, because the arithmetic will be done using millimeters.

4. Log the above circumference measurement into your notepad to help perform the age calculation. You may also want to keep a running log of the tree trunks that you have measured for future reference or for comparisons later on.

5. Divide the above measurement by 12 millimeters if the tree has grown within close proximity to other trees or by 25 millimeters if it has been growing on its own. The 12 or 25 millimeters denotes how much the tree trunk has grown per year. So, if you have a circumference measurement of 100 millimeters, 100 ÷ 25= 4, or 100 ÷ 12= 8.333. This would mean that if the tree trunk grew obstructed by others it would be approximately four-years-old; if it has grown alone in its environment it can be determined to be just over eight-years-old in age.

Tips & Warnings

• It is also possible to determine the approximate age of a tree trunk by counting the rings that make up its core. Each ring counted, is equal to one year of growth life.

• When taking measurements of a tree trunk, or using another method to determine its age, be careful not to damage it in any way. Even though the tree trunk may no longer be aiding the growth of a tree, it still may be harboring organisms that are important to the ecology of the area.

Resources

• More information on trees and the environment