Trees for life (biodiversity)

Dead or alive, trees support a vast range of animals, plants and fungi. Birds and bats, for example, are attracted to old, thick trunks due to their superior insulation.

Woodpeckers often start on a live tree by pecking small holes and waiting for fungi to invade. They remove the resultant mushy wood as it develops, before the cavity becomes too deep for their family.

Other birds benefit from the woodpecker’s departure. Nuthatches use mud to shrink the entrance and keep predators out, whereas owls need to wait for multiple cavities to merge (or a trunk split).

As wood fibres conduct sound superbly (think musical instruments), birds living in tree holes use this phenomenon as an alarm that amplifies the sound of predators like squirrels.

Bats inhabit old woodpecker cavities for a few days before moving on, as longer can lead to parasite infestation. Smaller species such as the pipistrelle can fit into nooks and crevices.

When a tree breaks, insects and fungi proliferate – ones that specialise in specific tree parts or stages of decomposition. These are typically not dangerous to living trees, which are too fresh.

A rotting trunk attracts wood ants, beetles and fungi. Beetles and their larvae reside long-term, fuelling the cycle by attracting fungi with their droppings.

Many woodland animals are specialists, e.g. water-filled trunk cavities support obscure life forms that require minimal oxygen, such as bumblebee hoverfly larvae.

Overall, higher levels of biodiversity lead to a more stable woodland ecosystem with less chance of any species dominating.

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Image: ralph-4 (Pexels)