Old Tjikko is a 9,550 year old Norway Spruce tree, located on Fulufjället Mountain of Dalarna province in Sweden. Old Tjikko is the world's oldest living individual clonal tree, however, there are many examples of much older clonal colonies (multiple trees connected by a common root system), such as "Pando", estimated to be over 80,000 years old.

The age of the tree was determined by carbon dating of the root system under the tree, not by dendrochronology, or counting tree rings. The trunk itself is estimated to be only a few hundred years old, but the tree as a whole may have survived for much longer due to a process known as layering (when a branch comes in contact with the ground, it sprouts a new root), or vegetative cloning (when the trunk dies but the root system is still alive, it may sprout a new trunk).

The oldest living non-clonal tree, verified by dendrochronology, is "Methuselah" (4,800 years old), a Great Basin Bristlecone Pine in California. Vegetative cloning and reproduction is common in many plants, such as the creosote bush (see "King Clone", estimated from growth rate to be almost 12,000 years old). Many other plants also may take advantage of this process either exclusively or in tandem with sexual reproduction, but dating or estimating the age of these organisms may not be possible without evidence (e.g., old roots, ancient remains, consistent growth rates).

Discovery and details

Old Tjikko is estimated to be at least 9,550 years old, making it the world's oldest known individual vegetatively cloned tree. It stands tall and is located on Fulufjället Mountain of Dalarna province in Sweden. For thousands of years, the tree appeared in a stunted shrub formation (also known as a krummholz formation) due to the harsh extremes of the environment in which it lives. During the warming of the last century, the tree has sprouted into a normal tree formation. The man who discovered the tree, Leif Kullman (Professor of Physical Geography at Umeå University), has attributed this growth spurt to global warming, and given the tree its nickname "Old Tjikko" after his late dog.

The tree has survived for so long due to the cloning process that many trees are able to take advantage of. The actual tree itself is relatively young, but is part of an older root system which dates back thousands of years. The main trunk of the tree may die and regrow multiple times, but the tree's root system remains intact which in turn, sprouts another trunk. The trunk itself may only live for about 600 years, and when one trunk dies another eventually grows back in its place. Also, each winter, heavy snow may push the tree's low-lying branches to ground level, where they take root and survive to grow again the next year in a process known as layering. Layering occurs when a tree's branch comes in contact with the earth, and new roots sprout from the contact point. Other trees, such as coast redwoods and western redcedars are known to reproduce by layering. The tree's age was determined by carbon-14 dating of the root system, which found roots dating back to 375, 5,660, 9,000, and 9,550 years. Researchers have found a cluster of around 20 spruce trees in the same area, all over 8,000 years old.

Previous researchers considered the Norway spruce species to be a relative newcomer to Sweden, with theories postulating the tree migrated into the area around 2,000 years ago. Trees much older than 10,000 years would be practically impossible in Sweden, because until around 11,000 years ago the area was in the grip of a world-wide ice age. Nature conservancy authorities are considering putting a fence around the tree to protect it from possible vandals or trophy hunters.

Other old organisms

The title of "World's Oldest Tree" can be a contentious one, as there are numerous examples of long-living clonal colonies of trees around the world. The record holders for an individual non-clonal tree are Great Basin Bristlecone Pine trees from California and Nevada in the United States, dated 4,000 to 5,000 years old by counting tree rings. The oldest is known as "Prometheus" (which is now dead), located on Wheeler Peak in Nevada; dendrochronology revealed the tree to be almost 4,900 years old. The oldest living non-clonal tree (verified by dendochronology) is "Methuselah" (almost 4,800 years old), a Great Basin Bristlecone Pine still growing in a "secret location" somewhere in the White Mountains of California.

A colony of 47,000 quaking aspen trees (nicknamed "Pando") covering in Fishlake National Forest, United States is considered one of the oldest and largest organisms in the world. It has been estimated to be 80,000 to a million years old, although tree ring samples determine individual trees to only average 130 years. A colony of Huon pine trees covering on Mount Read, Tasmania is estimated to be around 10,000 years old, as determined by DNA samples taken from pollen collected from the sediment of a nearby lake. Individual trees in this group date to no more than 4,000 years old, as determined by tree ring samples.

See also

• List of oldest trees
• List of famous trees

References