Conserving Bristol's ancient and veteran trees
Thanks to a generous donation from S C Johnson, we have undertaken a project to conserve a collection of ancient and veteran trees across a number of Bristol sites.
What are ancient and veteran trees?
Ancient trees are trees that have reached a great age compared to others of the same species; so a birch tree might be considered ancient if it lived to 150 years old, while an oak tree would only be considered ancient if it reaches at least 500 years old, and a yew tree would only be ancient if it was over 800 years old.
Veteran trees may look like ancient trees - gnarled, knobbly, bent, hollow - but can be any age. So while ancient trees are all veterans, not all veteran trees are ancient.
Why are they important?
Ancient and veteran trees are part of our historical natural landscape and can provide evidence of how the land around them was used in the past. They are also uncommon and under threat, and need specialist conservation work to ensure their survival.
As well being significant in their own right, ancient and veteran trees provide vital habitats for local wildlife, particularly fungi, invertebrates and lichen. Both Leigh Woods and Tyntesfield are sites of national significance because of their populations of invertebrates that are associated with these trees. A recent insect survey showed that 36 of their species are nationally rare, vulnerable and endangered, while one - a moth fly, Trichomyia minima - is completely new to science.
" 60% of the nation’s wildlife has declined in the last fifty years, so it’s crucial that these habitats are protected. The trees and hedgerows around Bristol are home to hundreds of species of invertebrates, fungi, lichens and mosses, bats, birds, butterflies and dormice, many of which are rare and endangered."
How can we look after them?
Veteran and ancient trees don't compete well with younger trees and they can often find themselves shaded out, causing them to die. To prevent this from happening, we clear the surrounding vegetation to allow the trees to reach sunlight. However, we have to do this slowly, over a number of years, as sudden exposure to sunlight can shock or scorch the trees we are trying to protect.
Veteran and ancient trees can also become too top heavy and split apart. We can prevent this from happening by undertaking careful specialist tree surgery to remove the branches that are causing the problems.
Day to day, we avoid removing deadwood and fallen branches from around the trees. This is because rotting dead wood replenishes nutrients in the soil which are needed by the trees, and the woodland in general, and provides vital habitats for rare invertebrates.
By not climbing these old and fragile trees, or building dens against them, we can prevent their bark becoming damaged.
Where are the trees?
The trees are located at a number of National Trust sites across Bristol and North Somerset; Leigh Woods, Tyntesfield, Shirehamption Park, Failand and Clevedon Court, making this collection one of the largest in the South West.
What have we been up to?
Conserving these trees forms part of a five-year project to ensure that they are well managed and protected. Work began in autumn 2017 with specialist tree surgery and the thinning of vegetation around the trees most under threat.
As part of the project, we will also be planting new trees that will become the veteran trees of the future - in over 150 years' time.