July 22, 2013 Australia’s Living Pine-osaur: Wollemi pine
On September 10, 1994 a New South Wales naturalist named David Noble abseiled into one of the more than 500 canyons in Wollemi National Park – some 60 miles east of the megalopolis of Sydney – and discovered a stand of prehistoric coniferous Wollemi pines, representing the 110 million year old supercontinent of Gondwanaland.
The discovery of Wollemia (named after the national park is from the Aboriginal Darkinjung dialect meaning ‘look around you’) nobilis (after David Noble) was likened to finding a small dinosaur alive on Earth.
How had Wollemi pine, which was thought to have perished more than 35 million years ago, managed to survive?
One hundred and ten million years ago lush ecosystems thrived near the South Pole. Australia, India and Madagascar were still attached to the Antarctica.
For months on end the only light during winter darkness was the spectacular electromagnetics from the aurora australis (or the southern lights).
Conditions were humid but cool and billions of insects flourished including: fleas, spiders, bees, cicadas, cockroaches and mosquitoes.
Dinosaurs of every variety existed: carnosaurus, kangaroo-sized Leaellynasaura with specially adapted eyes to cope with winter darkness, and pterosaurs flying above ginkos and new evolving Wollemi forests.
Evolving in the high latitudes with low light condition for many months, the trees of those times including the Wollemi had vertical canopies that ran parallel to the trunk which maximized the amount of low-light available. (More recently evolved trees have canopies that are parallel to the ground enabling them to catch sunlight higher in the sky.)
About 40 million years ago Earth was a hothouse. Carbon dioxide levels were about 1,500 parts per million (today they are 392 ppm) and the oceans were at least 425 feet higher.
The oceans were very warm and they held far less carbon dioxide thus increasing the fraction that stayed in the atmosphere. A warmer atmosphere held more water vapor. Furthermore increased volcanism ejected more carbon dioxide into the atmosphere and methane hydrates may have melted in the ocean due to higher water temperatures increasing greenhouse gases and thus Earth’s temperature.
During this time the Antarctic and Australia were still joined and annual rainfall was in excess of 8 feet.
Thirty eight million years ago Australia broke off Antarctica and began to drift northwards. This facilitated a current of freezing water to circulate westward around the southern ocean, blocking the passage of warm equatorial waters to the Antarctic and sentencing the South Pole to an ice cap and Australia to desert.
The greenhouse of 35 million years ago became an icehouse.
Unimaginable climate change gripped the world from 24 to five million years ago. And two million years ago, the last glacial period the Pleistocene tightened the noose on Earth and in particular Australia as levels of carbon dioxide plummeted to as low as 180 ppm.
The westerly winds scoured Australia and blew away close to an entire continent worth of vegetation. It favored fire and life forms that were generalists and promoted the ability to spread – perfect for both eucalypts and people.
The lush Wollemi pine forests of 100 million years ago were beleaguered. By two million years ago Wollemi probably only lived in about 10 gullies in the Blue Mountains of New South Wales and they were wiped out except along one creek-line.
Today, all that remains are two relic coniferous stands (about a mile and a half apart) of Wollemi pines that are sticking up amongst a flowering angiosperm rainforest.
Even more bizarre – the Wollemi trees are all genetically identical, although about 5,000 viable seeds are produced each year.
Forest biologists believe that the remaining Wollemi forests in New South Wales must have been extraordinary genetically similar before climate change forced them into a very low genetic variability, and over thousands of years they have further exaggerated by cloning into one big stand of pines that somehow split into two.
Of the 50 species of plants collected from the two Wollemi forests, one third are new to science including lichens and fungi. Four plants contain potent medicinal properties being explored by pharmaceutricals.
The fungus that is intimately associated with Wollemi pine roots in a life sustaining symbiotic or mutually beneficial process produces taxol (previously only known from the North American Pacific yew tree). Taxol is an efficacious cancer-fighting drug used to combat ovarian, breast and lung cancers, cardiovascular disease and AIDS.
Climate change may have painted this astonishing tree species into one remaining creek-line and although they have no remaining genetic variability, Wollemi pine has stayed the course for over 100 million years on our planet – miraculously obviating the end-game.
Text © by Dr Reese Halter 2013. All rights reserved.
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