“How old is that tree?” is one of the most common questions asked of arboriculturists. “I won’t know without cutting it down and counting the rings” is one of the most common answers.
While in arboriculture, we are rarely concerned with the chronological age of trees, we do, in most contexts the ‘life stage’ of the trees that we inspect.
What do we mean by ‘life stage’, how do we confirm it, and how do we categorise it?
Afterall, trees of the same species in different growing conditions can exhibit the features of ‘oldness’ and different stem diameters at different chronological ages.
And trees of different species might be considered young at similar chronological ages but mature at very different ages.
And then, of course we have ancient trees…
When we produced the Individual Tree Data Standard with FR and OU we provided categories that were aligned to BS5837 and descriptions were adapted from those in
Trees in Towns II, but acknowledged that ‘tree life stage is difficult to define and to measure. Categories and descriptions in
available guidance are imperfect and are the focus of much debate.’
Maybe this would be an interesting subject for a workshop, to better define how we assess and categorise life stage but maybe it is not necessary.
The commonly used life stage categories from BS5837:2012 are young, semi-mature, early mature, mature, over-mature…
…so, to test how much variation in approaches there might be; how do you differentiate between ‘semi-mature’ and ‘early mature’?