Hollow tree trunks: what are they good for?
Citizen science officer
If there’s one thing to get you close to nature it’s taking a step inside a big, hollow tree.
Stand inside an ancient tree and you are standing inside a piece of history. The hollow centres of ancient trees have even housed dinner parties, preacher’s pulpits and bullpens. It’s said that the centre of the Bowthorpe oak, in Lincolnshire once held 39 people within the trunk!
But why do trees hollow out and what are the benefits?
Why do trunks become hollow?
A hollowing trunk is a natural process and it’s not necessarily a sign of an ailing tree. The centre of the tree is deadwood which is slowly decayed by fungi. The fungi is perfectly happy in the deadwood and will rarely touch the living sapwood.
The tree has spent years storing up minerals in the wood in the centre of the trunk. As this wood is decayed the minerals are released and can be used once more by the tree. Along with the yearly supply of leaves and any decaying branches, the hollowing trunk is providing the tree with recycled nutrients, helping it to live longer.
There are other benefits to being hollow. A hollow tube may react better in high winds, allowing the tree to bend with the wind.
Credit: Ed Parker / WTML
Who lives in the hollows?
The hollow trunk is an ideal location for wildlife. There’s protection from extreme weather and the temperature will be much more constant than outside.
A hollowing trunk can provide a nesting or roost site for bats and birds. The bottom of the trunk can be a good location for a hibernating hedgehog or a snake to lay its eggs. Lots of fungi, epiphytes and invertebrates will also colonise a hollowing tree.
Famous hollow trees
- The Borrowdale Yews, Cumbria, were celebrated by Wordsworth in his 1803 poem, Yew Trees. The largest yew is over seven metres in girth and can hold four people inside.
- The Marten Oak, Cheshire, was referred to as the largest tree in England in 1880. It has served as a bullpen, a pigsty and a Wendy house over the years.
- The Crowhurst Yew, Surrey, is a churchyard tree. The tree has a door to get to the centre, which in 1850 housed a table and benches.
- The Pulpit Yew, Denbighshire, North Wales is home to an outdoor lectern. Steps lead through the hollow of the tree up to a raised seat and podium. Legend has it that John Wesley, founder of Methodism once preached here.
Protecting hollow trees
The UK has thousands of ancient trees - volunteers have recorded over 180,000 for the Ancient Tree Inventory! These trees are important to our heritage and wildlife, yet they don't get the protection they need.
We know thousands more are out there and we need your help. Adding a record only takes a few minutes, and the inventory website gives you all the guidance and tips you need.
Mapping where they are takes us a step closer to helping them. Every tree added to the inventory helps us monitor threats and plan how to conserve these trees in the future. Every record counts.
Explore the world of ancient trees
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Ancient yew trees: the UK's oldest yews
Trees woods and wildlife
Dead and decaying wood is one of any woodland's most important microhabitats. Learn more about why we need more of it, as well as the rare and endangered beetles, colourful fungi and other threatened wildlife that relies on it.