User: How can you tell how old a tree is?
Assistant: The size of tree has a direct correlation on how old the tree is.  The wider the diameter and circumference of the tree the older it is.  When a tree is cut down there will be inner rings in the stump that describe the tree's age as well.  A tree's diameter will increase in size about 2.5 centimeters per year.  You can estimate the age of a tree by measuring the circumference of the tree in centimeters and then dividing it by 2.5 centimeters.  It will be important to measure as close to the ground as possible to get the most accurate measurement for the tree's age.