Why do Some Trees Grow Multiple Trunks?

Have you ever wondered why some trees grow with more than one trunk? There are actually numerous reasons for the phenomenon. Read on to learn what causes it, and why, if you have a tree with multiple trunks, there are special ways of caring for it that you need to know about.

What causes trees to grow multiple trunks?

Most trees grow with a single trunk. But have you ever seen, or do you have a tree on your land that has more than one main trunk? Maybe it has two, or three? Maybe even more? If you’ve ever wondered what causes this to happen, read on to discover what’s behind the ‘multiple trunk phenomenon’.

Genetics

Some species of trees are genetically inclined to grow multiple trunks as part of their natural growth pattern.

The English oak is one of the UK tree species that is most predisposed to multiple trunks. The common ash tree is another.

Damage or stress

External factors including disease, physical damage or environmental stress can cause a tree to develop more than one trunk.

When a tree responds to stress or injury, it may produce new shoots to compensate for loss or damage to its main trunk. If this happens early on in the tree’s life, these new shoots could turn into additional trunks.

In addition, damage to the main trunk, for example storm damage, can cause it to split into multiple trunks.

Adapting to the environment

Depending on where the tree is growing, it may develop additional trunks as a strategy to compete for sunlight or nutrients. This tends to happen more where lots of trees are growing close together and the roots are competing for space.

The ageing process

As trees mature, some species develop additional trunks as part of the ageing process. This is more common in deciduous trees.

Inosculation

Inosculation is a natural phenomenon whereby the trunks, branches or roots of two trees grow together, leading to the formation of multiple trunks.

What are the benefits of multiple trunks?

Multiple trunks can benefit both the tree, and the environment, in a number of ways:

Higher environmental rating

Multi trunk trees have a greater foliage mass than trees with single trunks. This gives the tree a higher environmental rating, which means they absorb more carbon, play a greater role in cooling urban areas, and do a better job of protecting against floods and water pollution.

Richer wildlife habitat

The intricate structure of multi-stemmed trees provides a rich habitat for a wider and more diverse selection of bird, animal and insect species.

The various recesses and crevices in trunks and boughs provide protection, seclusion and breeding grounds for a significant number of species.

Characterful aesthetic

Multi trunk trees can be considered a unique garden feature, with a characterful presence and aesthetic appeal.

The additional shade provided by the wider canopy can also be a significant advantage during the hotter months of the year, making trees with multiple trunks perfect for open landscapes and parks.

Greater tolerance to damage and disease

Trees with more than one trunk tend to possess a greater tolerance to wind and storm damage as the trunks provide support for each other. They are also less vulnerable to disease.

Caring for multi trunk trees

Whilst multi trunk trees are less prone to damage and disease, they may require more tree pruning due to the presence of multiple trunks. A qualified tree surgeon will help you by assessing the tree and ascertaining the right type and level of pruning required to keep it safe and healthy.

Looking for professional help in caring for your trees? Our highly experienced, fully qualified, helpful experts here at TH Trees Ltd are ready to help. For personalised assistance, you are welcome to get in touch.

Images copyright Sarah McInerney 2023

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