How do you tell an trees age?

Question: How do you tell an trees age?
- Keywords:
  plant
Asked by beccawilko to Angus, Hannah, Simon on 28 Jun 2013.
- Simon Holyoake answered on 28 Jun 2013:
  
  well if you don’t mind cutting the tree down, you can count the rings, remember a tree has two different coloured rings, one for spring, which tends to be light, and a darker summer one
  
  if you don’t want to cut the tree down, and don’t know when it was planted, you can use a tool called an increment borer, which is like a hand drill you push into the tree and remove a small column of material, you can then count the stripes in the same way as a cut down tree
  
  You can also measure the circumference of the tree and compare it to the average ring width for the particular species of tree to calculate the age

Question: How do you tell an trees age?