Last week I fielded for the umpteenth time one of those queries that if you’re working in urban green space, you’ve probably been asked a thousand times. No, it’s not the one about the Swans, it’s the one about Ivy, the one that goes ‘what are you going to do about the Ivy? It’s killing the trees! Why aren’t you doing anything? You people don’t know what you’re doing…’etc. etc. and so forth.
It’s a common complaint – the notion that Ivy in someway ‘strangles’ trees. I can even recall a time when, as a volunteer, I was instructed to cut sections through some thick Ivy climbers for this reason. Where does the ‘myth’ come from? I have a theory on this – trees covered in Ivy are probably better structurally supported when they die. Therefore Ivy bound standing deadwood is more likely to remain where other, none Ivy bound deadwood may fall. Does this, therefore, give a false impression to the casual viewer? Ivy is also evergreen, which may in winter further exacerbate the miscomprehension. It is not a parasitic species, but will also thrive better on trees that are already ‘on the way out.’ There is a definite confusion over cause and effect when it comes to Ivy, demonstrated nowhere better than the comments under this piece.
In short, Ivy can cause problems, but ‘choking’ trees isn’t generally one of them. They do swamp borders, and perhaps the mental trauma this has caused many a gardener is part of the reason it can be so divisive, but thought about logically, how could they even ‘choke’ a tree? Perhaps some people did not pay enough attention in biology at school.
What Ivy in trees does do, is provide refugia and habitat for a whole host of invertebrates, nest sites for birds and even roost sites for bats. Berries also provide essential food in winter for some species and may be of benefit to Pine Martens. It may become overly dominant in a woodland, but that is where effective and thought-through management comes in to ensure that diversity and mix of species and ages. There is also an aesthetic argument (apparently), and this may be of more relevance to formalised parks than wild wood, but I for one do not think questions of aesthetics should come into wildlife management. So if you’re about to chop-out sections of your ivy climbers, consider this – which is better from both an aesthetic and bioviersity perspective, a dead tree covered in live ivy, or a barely-live tree covered in dead ivy?