Some trees just don’t know what it means to grow old. Discoveries of centuries-old trees, which seem not to have suffered the passage of time in any way, have led some scientists to wonder if these giants have found a way to cheat death.
An article recently published in the journal New Phytologist entitled “On tree longevity” returned to analyse a topic long discussed among botanists, but as yet unsolved: According to the evidence currently available to us, trees never die of old age but only due to action by external agents; does this mean that, if trees remained undisturbed, they would potentially be immortal?
The authors of the study, two Italian researchers (Gianluca Piovesan, professor at the University of Tuscia, and Franco Biondi, from the University of Nevada), start from a very concrete premise to pursue their own thinking: from analysing the tissues of old trees, there is no evidence of ageing in the cells responsible for growth (meristematic cells) nor any indication of genetic changes that could lead to the death of the tree.
This extraordinary longevity (over 2,000 years of life) has so far been found in six genera of conifers: Fitzroya, Juniperus, Pinus, Sequoia, Sequoiadendron and Taxodium. Among these are real champions of longevity, including Prometheus and Methuselah: two trees belonging to the Pinus longaeva species estimated to be just under 5,000 years old.
However, dating these trees is no trivial matter: there are several other candidates for the title of oldest tree in the world for which direct measurements (ring count or carbon-14 method) are not possible and whose age has been estimated by indirect methods.
But why are we so interested in knowing and studying the age of trees?
Obviously it’s not just out of pure scientific curiosity: first of all, these centuries-old giants, like all trees, sequester tons of atmospheric carbon and store them in their immense trunks, helping to slow down climate change. But besides that, the rings of these trees are real living historical records and can provide us with very important clues about environmental conditions thousands of years ago.
So here we come back to the question that opened this article: can trees live forever?
We can say that while most scientists are sceptical, we currently have no evidence to prove otherwise.
One thing is certain: the idea that a tree can potentially live forever is not only incredibly romantic, but also very interesting from a scientific point of view.
Will scholars be able to find a definitive answer to this question?
As a scientist I hope so, but deep down I would like this mystery to remain unsolved a little while longer.
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