The other day I was visiting a site which we did some work on some years ago, when I was struck by a couple of large Populus logs laying off to one side. They had obviously been there for quite some time, the bark had largely flaked off and the wood is colonised by a wide range of fungi…
I was struck by the beauty of the fruiting bodies of the fungi, but what I found even more striking the condition of the wood in view of the fact that apparently these trunks have been lying there for 18 years! That is a long time for a wood which I would have assumed would have decomposed to a fairly high degree over such an extended period. Not so. The wood is still firm with little sign of decomposition.
This got me thinking how we often have the tendency to try to fit complex issues into handy boxes, creating a model of the world surrounding us that is easier to handle and more palatable. Fungi, for instance, from an arborist perspective spell trouble. They are often an indicator of stress, decay or mechanical damage. Certainly, when performing a visual tree assessment this is the kind of thing we will pick up on: Wearing my VTA goggles, fruiting bodies are not good news.
Yet this is only one way of viewing fungi and it falls short of a more complex reality. Neville Fay of Treework Environmental Practice, who has done lots of work on veteran tree preservation speaks eloquently to the beauty of fungi, of how they are an integral part of life cycles of trees, performing an essential task in a process of decay and renewal. And indeed, autumn is that time of year when I cannot help but marvel at the diversity of fungi, the myriad shapes, sizes and colours they come in, some big, some small, some toxic, some edible, some beautiful, some less sightly… sometimes it seems to me as though nature let its creativity off the leash when it came to thinking up fungi – yet of course, much more than merely being pretty, each of them performs a specific task in a specific niche – in a highly efficient manner.
Indeed, the way in which we behold something is all a matter of perspective and context. Obviously if we are trying to preserve a tree which is valuable to its owner, extensive colonisation of the base of the tree by fruiting bodies (depending on the species) it is probably not good news, yet in all honesty this does not make the fungi bad guy, as often as not the root of the problem lies somewhere else, such as damage to the roots during construction work, compacted soil, drought stress, large pruning cuts, superficial damage to roots by lawnmowers etc.
It will be interesting to see where this goes in the coming years as our knowledge of how exactly fungi decompose wood improves. Amongst others, Francis Schwarze has been doing interesting work in this area, researching natural antagonists, such as Trichoderma harzianum which he has used to counteract fungal infection in trees. I believe we stand to gain through an improved knowledge of the complex interactions between trees and fungi, as they have co-existed since the very beginning and viewing fungi as inherently bad falls short of a much more complex reality.