There Are 9,000 Undiscovered Tree Species, Kept Genetically Healthy By Ancient Trees
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Ancient trees contain genetic information vital to helping forests adapt to changing conditions
These trees which often number just 1% of the population, and live 10-20 times longer than others, are irreplaceable in a forest biome.
There may be 9,000 tree species undiscovered by science, making this research more relevant in keeping threatened ones alive.
Ancient trees are unique, unrecoverable organisms that shape the genetic lineages and resilience of forests throughout the centuries, a new study finds. It’s a claim that puts data and word to a feeling well-known to any who have stood in the presence of monumental, or ancient trees.
Unlike animals, which tend to produce weaker offspring as they get old, the study found that ancient trees, defined as about 1% of the population, and which average 10-20 times the age of their surrounding kin, maintain their fecundity as they enter their antiquity, and continue to produce generations with the unique survival properties which allowed them to become “lottery winners” as the authors describe them.
Their superior genes sustain them through multiple climatic cycles and periods of warming, cooling, wetting, and drying, and pass the knowledge about how to adapt to these conditions onto their offspring.
The number of these ancient trees in a forest biome tends to correlate with the resilience of that ecosystem, and the fewer there are, the more often the forest suffers massive damage from environmental effects.
“In our models, these rare, ancient trees prove to be vital to a forest’s long-term adaptive capacity, substantially broadening the temporal span of the population’s overall genetic diversity,” said Chuck Cannon, Ph.D., director of The Morton Arboretum’s Center for Tree Science in Lisle, IL.
Existing arborology, tells us that ancient trees connect, coordinate, and even “nurse” the forest. There are “mother trees” which cultivate an area around them to serve as a nursery. They maintain social cooperation, and trees will entangle their roots together, sometimes over large distances, in order to share nutrients and defend individuals that are sick or hungry, or that thousands of trees will somehow coordinate when to release their seeds in order to avoid predators like boar and squirrels.
“The term Mother Tree was already being mentioned by the Brothers Grim, the famous fairytale writers in the 19th century, so it’s long known wisdom,” author and forester Peter Wohlleben, told WaL in July, “Even foresters know there is a certain ‘education,’ by shadow, by making a slow growth possible”.
It’s possible these maternal skills also exist in ancient trees, and that they also are passed down, as Cannon et al. showed, to proceeding generations.
This genetic knowledge, the team showed, is lost when these trees die, and that a forest without them has no knowledge about how to survive climatic shifts.
The researchers found in their models that the maximum age that trees could reach was particularly sensitive to the lower range of observed mortality rates. However, at higher mortality rates, like those that might be seen as resulting from climate changes, the ability of trees to reach the same impressive ages is very limited or virtually impossible.
“As the climate changes, it is likely that mortality rates in trees will increase, and it will become increasingly difficult for ancient trees to emerge in forests,” said Cannon. “Once you cut down old and ancient trees, we lose the genetic and physiological legacy that they contain forever, as well as the unique habitat for nature conservation”.
PICTURED: An infographic that shows the existing tree diversity and cover, continent by continent. PC: CAZZOLLA GATTI ET AL. / PNAS.
Known unknowns
Another study published last week, this time from the Proceedings of the National Academy of Sciences, found that while there are 63,000 known tree species on Earth, there are likely another 9,000 which remain undiscovered, with potentially as many as 40% of these mystery species dwelling in South America.
With so many known unknowns, Cannon’s work becomes so much more valuable. Without knowing the extent of these trees’ habitat and range, it is impossible to find their mothers and ancients that can help their forests survive through the centuries.
The authors note that while forest restoration and tree planting efforts are important tools to improve both local and global environments, ancient trees cannot be recovered or regenerated without many centuries and generations of trees passing. They are an emergent property of old-growth forests that are impossible to recreate in newly regenerating forests, and must be protected, urge the authors.
At the recent meeting of the parties to the Paris Climate Agreement, President Joe Biden alongside other nations signed a promise to attempt a global end to deforestation, which is still taking place at around 10 million hectares, or 24 million acres, per year.
Perhaps more worryingly in the face of these two new papers is the fact that 8,000 tree species are threatened with extinction, while 45% of all trees in the world belong to just 10 species.
At these rates the forest as we know it is heading slowly towards a state in which it becomes a museum, and the wild forests of the future will be superorganisms with amnesia and without a past. WaL
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