Each year, most trees add an extra layer of growth to their trunks. As the tree gets older, the inside of the trunk looks like it is made up of a series of circles.
The center of these circles, or the absolute core of the tree, is known as the pith.
This use of tree-ring dating to find the age of a tree is also known as dendrochronology.
Trees that cannot be dated using the tree-ring method include some species of palm trees, as well as certain trees that grow in desert conditions.
These types of trees are known as monocots, and their age is determined mainly by comparing them with other plants.
Taking core samples at a point in the year where pests and rain are less likely to be present can help lessen some of this risk.
Once the core sample is obtained, the tree’s age is determined by counting the number of rings evident in the sample.