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Hollow tree trunks: what are they good for?

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. But why do trees hollow out and what is in it for the tree?

Hollow trunks 

The hollow centres of ancient trees have 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. At other points in its long history the tree was a venue for al fresco dining with seating for 20 people. 

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 very rarely, if at all, will touch the living sapwood. 

The Bowthorpe oak in Lincolnshire once held seating for al fresco dining with enough room to seat 20 people. (Photo: WTML)
The Bowthorpe oak in Lincolnshire once held seating for al fresco dining with enough room to seat 20 people. (Photo: WTML)

It’s not so bad to be hollow 

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. 

Who lives in the hollows? 

The hollow trunk is an ideal location. 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. Plus there will be lots of fungi, epiphytes and invertebrates which will 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.

Protect our hollows

Just one hollowing tree can be a home for lots of different wildlife. These vertical nature reserves need our protection, that’s why we record ancient and special trees onto the Ancient Tree Inventory

Log a hollow tree near you, on our interactive map.

Ancient Tree Inventory