how do I measure
the age of a tree?
basic method
You can get an estimate of a tree’s age without cutting it down and counting the rings! To work out a tree’s age, simply use its girth – the distance around its trunk – as the girth will increase by approximately 2.5cm a year.
To do this, just measure the girth – at about 1m from the ground. Make sure you measure to the nearest centimetre. Then divide the girth by 2.5 to give an age in years.
A tree with a 50cm girth will therefore be about 20 years old. The rate of growth will differ according to what type of tree it is.
a note on tree types
Some types of tree, such as oak and beech, will grow quite slowly, and so you should divide the girth measurement by 1.88. Pine trees, however, are very fast growing, so you should divide the girth measurement by 3.13.
Other factors will affect the growth too, such as how close the tree is to other trees. So, if a tree is on its own, it has the space to grow faster than trees in a wood. An average woodland tree will only increase its girth by about 1.25cm per year.
trees on the Friern Manor Farm Estate
Look out for old oak trees as these were often used as field boundary markers.
The area along Wood Vale, towards Lordship Lane, was once full of orchards. Pear trees often grew in this district and can still be seen today.
I’ve identified the age of a tree – what do I do now?
Record your tree observation data, on the free iNaturalistUK app (see how do I record and classify plants?) and write the approximate age of the tree in the notes section of your tree observation.
We aim to record this information on a map of the Friern Manor Farm Estate catchment area, just as we will with any other flora you observe.