Recently I was asked to review a unit of competency. When I say, ‘I was asked’ the ask was to industry, and when I say ‘industry’, it was the industry in the widest possible context, so really every man, woman, child and their dog was asked to be involved. I suspect cat owners weren’t asked only because no one really ‘owns’ a cat, but I’m sure feedback from people that entertain cats would have been greatly received as well.

The consultation was for a training provider’s version of one of the new, New Zealand Certificates in Arboriculture. The particular unit of competency was on visual tree assessment. Fantastic, a core knowledge requirement for any arborist and great to see the topic included in the qualification. So far so good, but what struck and concerned me about this particular unit of competency was the grand collection of words; ‘Demonstrate an understanding of the principles of shape optimisation – identify symptoms of high stress points and instances of shape optimisation in a tree’

I am always nervous when I see something expressed in more words than are needed, especially when clarity is key. It is one of those red flag things for me. I see verbose statements in reports all too often and every time I find myself asking, who’s the author trying to impress and why?

Visual tree assessment at this level shouldn’t be complicated – concepts and awareness are what is required. Visual tree assessment involves looking at trees, it should be really cool.

‘The principles of shape optimisation’ – this is just uniform stress; fill up a glass of water real slow – if you’re good you can fill it to a level above the top of the glass – the water tension is uniform, uniform stress. Tap the glass and the water will spill – you’ve created waves, caused weaknesses, made the stress uneven. Simple science like that can be even be demonstrated with beer – science can be taught in a pub!

‘Symptoms of high stress points’, this one reeks of fear and here we have the potential where a little bit of knowledge can be dangerous. Trees are self-optimising structures, they try to create and/or maintain uniform stress by shedding leaves and twigs and/or growing more wood where needed. It is this growing more wood where needed (‘response growth’) that causes the changes in trunk or branch diameter that can be seen – the bases of visual tree assessment. But if you are only looking for symptoms of high stress points, you are probably looking for the wrong things…

Because trees have been around for 370 million years they know how to deal with stress, they don’t waste wood by growing it where it’s not needed. If a tree is able to grow more wood, put down response growth, then by default it must be healthy enough to be able to grow. Response growth can be seen as a good sign. But when we don’t see a change trunk or branch diameter – is that because the tree is uniformly stressed or is it because the tree is unable to grow response growth? A symptom of high stress points could well be a lack of symptoms…

When it comes to shape optimisation we are rapidly entering the realms of artistic licence. What is the optimal shape after all? In humans, the visible response to repeated mechanical stress is muscle growth or broken bits…. fret not, this is just an example, with maybe a wee bit of artistic licence thrown in.

If you go down to your local gym you may well be confronted by buff beasts with bulging biceps flexing in front of a mirror – beauty is indeed in the eye of the beholder. The shape optimisation that these selfie-taking buff beauties have achieved is clearly visible. On the other hand, if you were to watch weightlifting at the Olympics you would most likely not see bulging biceps. Clearly, Weight Lifters have achieved a different shape optimisation, their strength is clearly visible yet their biceps are not. Then, if you go down to your local pub, you would most likely see people that looked like Weight Lifters but they are not Olympic athletes – same shape optimisation, yet completely different abilities. Shape optimisation in trees is exactly the same – exactly the same in that the external appearance may or may not be a reflection of strength.

Visual tree assessment is fantastic knowledge and learning about it can be / should be fun – trees are amazing structures and they have been amazing for 370 million years, let’s not spoil something so beautiful with shape optimisation stress points and instances of wordy twaddle.