World's Oldest Living Tree -- 9550 years old --

The spruce tree has shown to be a tenacious survivor that has endured by growing between erect trees and smaller bushes in pace with the dramatic climate changes over time.

For many years the spruce tree has been regarded as a relative newcomer in the Swedish mountain region. "Our results have shown the complete opposite, that the spruce is one of the oldest known trees in the mountain range," says Leif Kullman, Professor of Physical Geography at Ume? University.

A fascinating discovery was made under the crown of a spruce in Fulu Mountain in Dalarna. Scientists found four "generations" of spruce remains in the form of cones and wood produced from the highest grounds.

The discovery showed trees of 375, 5,660, 9,000 and 9,550 years old and everything displayed clear signs that they have the same genetic makeup as the trees above them. Since spruce trees can multiply with root penetrating branches, they can produce exact copies, or clones.

The tree now growing above the finding place and the wood pieces dating 9,550 years have the same genetic material. The actual has been tested by carbon-14 dating at a laboratory in Miami, Florida, USA.

Previously, pine trees in North America have been cited as the oldest at 4,000 to 5,000 years old.

In the Swedish mountains, from Lapland in the North to Dalarna in the South, scientists have found a cluster of around 20 spruces that are over 8,000 years old.

Although summers have been colder over the past 10,000 years, these trees have survived harsh weather conditions due to their ability to push out another trunk as the other one died. "The average increase in temperature during the summers over the past hundred years has risen one degree in the mountain areas," explains Leif Kullman.

Therefore, we can now see that these spruces have begun to straighten themselves out. There is also evidence that spruces are the species that can best give us insight about climate change.

The ability of spruces to survive harsh conditions also presents other questions for researchers.

Have the spruces actually migrated here during the Ice Age as seeds from the east 1,000 kilometres over the inland ice that that then covered Scandinavia? Do they really originate from the east, as taught in schools? "My research indicates that spruces have spent winters in places west or southwest of Norway where the climate was not as harsh in order to later quickly spread northerly along the ice-free coastal strip," says Leif Kullman.

The age of the tree was determined by carbon dating of genetically matched plant material collected from under the tree. The trunk itself is estimated to be only a few hundred years old, but the plant has 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).

Old Tjikko stands 16 feet tall and is located on Fulufj?llet Mountain of Dalarna province in Sweden . For thousands of years, the tree appeared in a stunted shrub 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 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 vegetative cloning . The visible tree is relatively young, but it is part of an older root system which dates back thousands of years. The trunk of the tree may die and regrow multiple times, but the tree's root system remains intact and in turn sprouts another trunk. The trunk 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 red cedars 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. Carbon dating is not accurate enough to pin down the exact year the tree sprouted from seed, but given the estimated age the tree is supposed to have sprouted around 7550 BC. For comparison, the invention of writing (and thus, the beginning of recorded history ) did not occur until around 4000 BC. Researchers have found a cluster of around 20 spruce trees in the same area, all over 8,000 years old.