Can trees really live forever?

Researchers studied a total of 34 Gingko biloba trees, ranging from three to 667 years old.¹ They looked for age-related changes in the cambium, a layer of dividing cells beneath the trees’ bark that generates growth of stems and roots after the first season.² They discovered that leaf size, photosynthetic ability, and seed quality – which are all indicators of health – didn’t worsen with age.

In an earlier study of nearly 700,000 trees, scientists found that a tree’s growth doesn’t slow down after hundreds of years. In fact, it speeds up. Over time, trees stopped getting taller but, like bodybuilders, they did get wider.³

So, does all this mean that trees can live forever? Well, that’s not an easy question to answer.

Whilst a 667-year life span is incomprehensible to humans – and even more so for the delicate mayfly, which lives for only a day – it’s relatively young for a Gingko. Amazingly, they can live for thousands of years.⁴

But while signs of deterioration from old age in trees might not be perceptible to humans in our lifetime, this doesn’t necessarily mean they’re immortal. Stress and strain are likely to eventually take their toll, but studies would have to take place over hundreds – or thousands – of years to say for certain.⁵

One possible sign of age-related deterioration was seen by the researchers studying the Gingkoes. They found that the older trees had thinner vascular tissue… but also concluded that the vascular cambium was capable of growth for hundreds of years, or millennia.

And so, saying for definite whether trees do or do not die from old age requires more data, and the problem with that is long-lived trees are pretty hard to come by.

The oldest individual tree (that we know about) is possibly a Great Basin bristlecone pine in California’s White Mountains, which is thought to be over 5,000 years old.⁶ The unnamed tree was discovered and a core sample taken in the 1950s, but the sample was left in storage until another researcher dated it in 2010. However, the core sample has since gone missing at the Laboratory of Tree-Ring Research, which throws some doubt on its status.⁷ What can be confirmed is that before then, another bristlecone pine, called Methuselah, took the “oldest known tree” title at over 4,800 years old.

There are also several clonal colonies which are much, much older. The Pando, or ‘trembling giant’, in central Utah is a colony made up of 40,000 trees, all of which are clones connected by a single root system.⁸ Some of the individual trees are estimated to be over 130 years old, but the root system is believed to be an astonishing 80,000 years old.⁹ 

So what is it about bristlecone pines that makes them so able to endure the slings and arrows of time? For one, they grow really slowly. By the age of 40, they will have barely reached 15cm (5.9 inches) in height!¹⁰ Another secret to their longevity is the harsh conditions in which they live. Cold temperatures and high winds – combined with their slow growth rate – encourages the growth of dense wood, which makes them very resistant to insects, rot, and erosion.¹¹ 

But if trees can indeed live forever, then why aren’t there any that are millions of years old, rather than thousands?

Whilst the researchers who studied the Gingko trees couldn’t definitively provide a response to whether trees are immortal, what they could say with more confidence was that they’re much more likely to die from an external incident, such as damage or disease, than they are to die of old age.

The longer a tree is around for, the more chances it has to encounter events that could kill it, such as storms, wildfires, or diseases. And whilst a tree can escape the Grim Reaper a number of times, the more it faces potentially life-threatening events the more likely it is to become vulnerable. For example, tree damage from a storm can make a tree more exposed to disease.

And then there’s human interference. Another bristlecone pine ‘Prometheus’, named after the Greek mythological figure, was cut down in 1964 after attempts to take a core sample went awry. It was only later that they discovered Prometheus was over 4,800 years old - the oldest recorded tree at that time.¹²  

And so, whether trees can avoid death from old age remains a bit of a mystery. But one thing we do know is that trees do not age in the same way we do. Not only can they far outlive us, but they also continue to inspire wonder within us as to whether - if left untouched - they could cheat death itself.

Discover more astonishing plant-animal relationships with new Sir David Attenborough series The Green Planet, which explores the wondrous interconnected world of plants. Find out where to watch in your region here. 🌱

Featured image © Reuben Jolley

1. Gingko biloba research, 2. Cambium, 3. Girth Gain, 4. The Incredible Age of the Ginkgo Biloba, 5. Doubts About Immortality, 6. The Great Basin bristlecone pine, 7. Mystery of the Missing Tree Core, 8. Pando Clone tree, 9. Lifespan of a Trembling Giant, 10. The Pando Clones, 11. Built to Survive