As an arborist, I thought that I had a fairly good understanding of life and death – a dead dog is a dead dog, rabbits exist in two states (alive or dead) and Schrodinger’s Cat is both alive and dead at the same time (until you open the box), but then I met an ecologist who suggested that a tree is a more alive when it is dead, and mostly dead when its alive. How can this be, and how can something as black or white as death, actually be… grey?

We know that there are trees that can regenerate in a type of Dr Who fashion, the above ground portion of the tree grows up then dies and a then a new tree regenerates from the roots. Some trees can do this hundreds and hundreds of times; but is it the same tree after all the parts have been replaced several times over? Other trees take this to the next level and form entire forest with hundreds if not thousands of trees growing up and dying down. These regenerating trees and/or self-cloning forests can survive for 10,000 years or more. There is nothing left of the original tree except its DNA – so is the original tree dead? Is DNA ‘alive’?

Such ponderous things require beer and consideration and I must confess that I have invested time in the pursuit understanding such matters, but the ecologist wasn’t playing by the rules. Musing on mega-organisms like forests or sub-cellular proteins is one thing, but the ecologist was talking about tangible things, things you can touch.

Visualise a majestic conifer if you will – yes, I know that I’ve just said, ‘things you can touch’ and now I’m asking you to visualise something, but go with it; visualise a tree perfect in every way – visualise the specimen example of all specimen examples.

Your perfect majestic tree is more dead than alive. Your perfect tree most likely 90% dead. I’m not sure about you, but a 90% dead tree didn’t come to mind when I first though about this. Only about ten percent of the cells in your tree may actually be living: the leaves (three percent), inner bark (phloem and cambium, five percent), and ray cells in sapwood (two percent).

In contrast, visualise a log in an advanced state of decay, visualise a rotting tree corpse laying on the ground. There is a reasonable chance that 35% of the bulk of that log (its biomass) is living. Your lump of rotting log has become a fungal mega structure with more living ‘tissue’ in it as a corpse compared to when it was alive as a tree.

Now visualise a standing tree in decline; a few patches of green but with tip die-back, bacterial ooze, cavities, fungal fruiting bodies and whatever else comes to mind – that tree has probably never been so alive.

As an arborist, I thought that I had a fairly good understanding of life and death, but it seems that I’ve killed a lot of mostly dead things, and in doing so I’ve prevented a lot of dead things making an awful lot of living things.

On the flip side – I have been planting trees (trying to replace some of the ones that I’ve killed). I don’t get to kill many trees anymore and planting is good, but maybe we should all stop removing all of the things that we kill. Keep planting, because we need new trees, but keep some of the dead stuff too – tree is a more alive when it is dead.