Bringing Back the Giants: to Clone or not to Clone by Peggy Edwards
Updated: Jan 11, 2019
The tallest, oldest and most massive non-clonal trees on the planet are the coast redwood (Sequoia sempervirens); the bristlecone pine (Pinus longaeva); and the giant sequoia (Sequoiadendron giganteum) respectively.
The tallest coast redwood, named Hyperion, grows in an undisclosed location in Humboldt County, California; the oldest known bristlecone pine - 5,068 years - is unnamed and located in an undisclosed location east of the Sierra Nevada in the White Mountains; and the most massive Sierra redwood, General Sherman, is located in Sequoia National Park in California’s Sierra Nevada.
The Latin species name, sempervirens, of the tallest redwood literally means “always flourishing (green)” – an apt name - when a coast redwood is cut or falls from natural causes, the tree begins to reproduce clonally from it's stumps, fallen logs, or roots.
If you hike through a second-growth coast redwood forest you will pass huge old-growth trunks surrounded by circles of 100-150 year-old second-growth trees. Standing in the middle of a circle of redwoods, also known as a “fairy ring,” and looking upward is an otherworldly experience as if you’re looking through a tunnel into the sky.
As mentioned earlier, the oldest bristlecone pine is 5,068 years old. The oldest giant sequoia is 3,018 years old, and while the oldest coast redwood is a mere 2,520 years old, if we consider it a clone of a parent that toppled it may well rank among the oldest trees on Earth.
Currently the oldest known clonal tree on Earth is a colony of 47,000 quaking aspen trees nicknamed Pando that covers 106 acres in the Fishlake National Forest of Utah whose root system is estimated to be 80,000 years old. The world’s oldest individual from a clonal tree is a 9,550-year-old Norway spruce named Old Tjikko located the in Fulufjället Mountains in Sweden.
In 2017, Save the Redwoods League, the nonprofit organisation whose mission is to protect and restore coast and Sierra redwoods, sponsored two studies by Lakshmi Narayan and Kevin O’Hara of the University of California, Berkeley to explore the genetics of three second-growth coast redwood stands.
Results of the studies demonstrated that redwoods growing close together in a fairy ring “were actually not clones approximately 10% of the time.” Even those trees connected at their trunk bases followed this ratio. The non-clonal 10% were the result of sexual reproduction, or sprouts from neighbouring redwoods, or even the result of mutations.
Sadly due to over-harvesting in the 19th and 20th centuries, only 5% of the original old-growth coast redwood forest remains today along a 450-mile strip of California and Oregon’s coastline. Fortunately, commercial growers, conservation groups and individuals are working to bring the forests back. Questions have been posed as a result of these efforts: where should the stock originate; how pure should the new stands be; are coast redwood sprouts genetically identical copies of the parent tree?
Narayan and O’Hara’s study showed that even within a relatively pure stand of second-growth redwoods there is some genetic diversity as opposed to laboratory-propagated clones produced by commercial timber operations for their re-planting efforts.
The researchers now advise those involved in coast redwood regeneration not to limit planting seedlings from a single parent, but to incorporate a mix of seedlings and sprout-originated trees in replanting the forest in order to resemble old forest conditions, maintain genetic diversity and to provide a more resilient habitat for threatened species that depend.
Written by Peggy Edwards. December 2018.
Peggy Edwards is a botanical illustrator and redwood aficionado. She has a BSc from the University of California and a Graduate Certificate Natural Science Illustration from the University of California, Santa Cruz. She has been a field Botanist, Naturalist and K-12 Teacher. She is one of the co-founders of the Scottish Redwood Trust.