A tree is a complex system for harvesting and storing the energy of the sun. The tree uses this energy to help build a strong body out of two special compounds called lignin and cellulose. Heartwood, the centre of the tree, is a ‘dead’ substance. This is because the living part of the tree, the xylem and the phloem, (one transports nutrients from the roots up the other carries complex carbohydrates made through photosynthesis down to the roots) is only the first 2-3mm of the wood, just below the bark of the tree.
This means that all that lovely sun energy is trapped in the wood, and there are many lifeforms that have evolved to release this store of energy, and this is why tree stumps and hollows are great places to look for all kinds of lifeforms!

Wood boring insects, such as stag beetles, spend most of there life cycle as grubs burrowing through heartwood. Many different fungi specialise in breaking down heartwood, Beefsteak Fungi, southern bracket and chicken of the woods can all be found here, doing this job. As the wood is softened by these lifeforms hollows form within the tree and other animals can move in, from woodpeckers to bats to hornets!