ESTIMATING THE AGE OF TREES

Short of cutting a tree down and counting the tree rings there is no accurate method for finding the age. Trees grow at different rates at different times of their lives. The soil type affects growth as does location. Nevertheless, a method has evolved that gives a good rule of thumb.

Method
Measure the circumference of the tree at 5 feet from the ground avoiding irregularities. Note the location of the tree.

1. If it is growing in the open:
i. up to 50cm circumference the growth rate is approximately 3.0 cm a year
ii. above 50cm it is 2.5 cm a year
2. If growing in a wood:
i. up to 50 cm circumference it is 1.75cm a year
ii. above 50 cm it is 1.25cm a year
3. If partly hemmed in:
i. up to 50cm 2.4 cm a year
ii. above 50cm 1.9 cm a year

Poplars, planes, Turkey oak, giant redwoods and Wellingtonia all average around 5 cm a year in the open.
Horse chestnut, lime and Scots pine average 2 cm a year.

The limitations of the method used for estimating age is well shown in the cemetery. Along the central avenue there are pairs of oak, birch and fir tree on opposite sides of the avenue. The oak ages are 132 and 82 years; the birch 93 and 71; the fir tree 59 and 52. It is presumed that each pair was planted at the same time. However, it is clear that the method can be made to work when dealing with large numbers of similar or same aged trees. There are 14 trees in the cemetery that were probably planted when the cemetery was opened in 1888 ie 115 years ago. The average age of the horse chestnut and the lime trees is 113.5 years. The average of the seven beech trees is 105 if they are regarded as having been planted in the open, which must have applied for at least the first 30 years of their lives.