Old oak
To mark National Tree Week, it is time to celebrate a veteran oak we have on the northern part of the reserve.
When you think of Caerlaverock you probably think about the huge flocks of geese, the saltmarsh or maybe the amazing freshwater environments we’re restoring. You’d be forgiven for not remembering mature aged trees. We don’t have a huge quantity of trees like this which makes the ones we do have extra special!
Before we get into it, I just want to make a quick note on the classification of trees. What makes a tree a veteran? It doesn’t have to be a certain age but needs to have some features such as gnarled and bent branches, hollowness and huge in size. For different species, these features appear at different ages and for oaks, this is at least 400 years old.
So why is this one tree so special? Well for starters, it takes so long for a tree to get to this size that if we lose them, it’ll be a long time again before we see younger trees reach this veteran status.
Oaks support the more diversity than any other tree in the UK, home to over 2300 species, acting like a huge skyrise apartment block. It’s difficult to know where to start when talking about the number of species using oak trees because of the huge variety!
For starters 1178 invertebrates use oak trees at a certain point of their lifecycle. Purple hairstreaks caterpillars feed on oak flowers and purple emperors loiter at the canopy of oaks where the butterfly feeds on aphid honeydew. Meanwhile, the acorns themselves are a food source for species like badgers, wood mouse and jays who cache the acorns which sometimes get forgotten and become new oaks.
As these giants age gaps appear in the bark creating large cavities which bats like the rare barbastelle and Bechstein's. Pied flycatcher, treecreeper and many owl species use them as areas to create nests in the breeding season. The bark itself can even be home to many different lichen, mosses and fungi.
And this list is only SOME of the highlights! I haven't even begun to go into deadwood which offers a completely different habitat.
Hopefully on your next walk around Caerlaverock you’ll keep an eye out for these veteran and mature trees and think about all they have witnessed in their old age but also the huge amount of life they’re now home to.
Words and feature image of oak by Jake Goodwin
