We spent the last few days of last year, up at the wood, giving some of our special trees the space they need to carry on living. These are trees that once grew in a much more open habitat, but now are hidden under the canopy; enclosed, shaded, in danger of being smothered. You can tell these trees had no initial need to compete with others for light; their branches, instead of shooting rapidly upwards to reach the top of the canopy, spread wide and welcoming. Many of these old trees are not species that ever grow as tall as the ash, oak, birch or sycamore, but they are the trees that bring biodiversity and interest to the wood such as spindle, crab apple, Lancastrian whitebeam, hawthorn and buckthorn. When we find these trees fighting to keep going, it’s tempting to stride in and make a clearing all round them, but counter intuitively, this could easily kill them. The situation is not as simple as it first appears; we need a plan to support them and when you look at some of the sorry examples of old trees that we have in the wood, you would be forgiven for wondering if they are worth it. But they are worth it. In addition to increasing the biodiversity of the woodland, many of these trees are veterans.
A veteran tree is defined by three guiding principles. They are1:
Trees of interest biologically, aesthetically or culturally because of their age.
Trees in the ancient stages of their life.
Trees that are old relative to others of the same species.
It isn’t enough to look at a tree’s size (trees grow at different rates) or at their absolute age (at 200 a beech is just becoming a veteran, an oak is only just maturing and a yew has barely started while at not quite 100, a birch is really old). Instead, it is the features of the tree that really characterise it as veteran, such as trunk cavities, water pools, decay holes, dead wood, bark crevices, fungal fruiting bodies, and epiphytic plants. These are the features that give these trees the ability to support a higher number of interdependent wildlife species than younger trees with many of the species being specialists only found on veteran trees; these are the features that make veteran trees really important in our the wood.
In a wider context, veteran trees are important for many other reasons. They are survivors from the past – some of the older yews in the UK predate Christianity – and as such are part of our heritage. Artists have drawn and painted them, poems and stories have been inspired by them and communities have found a common focus in trees associated with historical stories or myths. Looking at the position of veteran trees in the environment helps us understand earlier land management systems and the older a tree is, the more likely it is to be descended from the wildwood of Britain that existed after the ice age, possibly harbouring genes with good disease resistance.
Britain has one of the highest populations of veteran trees in Europe, but as with so many things, veteran trees need our protection. Half an hour with a chainsaw can fell the growth of centuries. We need to look after the veterans in our wood – hence the cold, wet days spent in the wood before New Year.
In order to prolong the tree’s lives, we do need to let more light in; too little light and the tree will die through lack of energy to generate sugar in photosynthesis, but too much light and the tree will be put under unendurable stress. Allowing in too much sun all at once makes the leaves vulnerable to scorching. The new movement of air around the tree and the removal of the canopy previously maintaining it in a damp atmosphere can combine with a woodland root system which is not up to the sudden change; the tree loses water much more rapidly and the root system cannot provide enough water to stop the tree desiccating to death. Sun shining on bark that was not previously exposed to its rays can crack hollow trunks as they dry out unevenly, and organisms associated with the tree can be adversely affected as the tree becomes generally drier and more unprotected. Clearly this process of letting in more light must be done with care. So at the close of 2020, we began a slow, planned, thinning process round particular trees that will take a few years to complete, possibly in some cases, as many as ten. But it’s a good feeling, giving these special trees the chance to thrive again, allowing a different, more spreading form of growth to develop in some areas of the wood, potentially creating a different atmosphere in places. In many cases, this process will also hopefully bring spring blossom back down towards the woodland floor. I am looking forward to seeing how these trees will react in the spring. I am excited to see how the trees develop when they have the space to live, not just survive. This wood has given us space – it’s time to give space back.
1Veteran trees: A guide to good management (2000) ed H. Read. Published by English Nature (now Natural England).