Thursday, May 21, 2015

Do trees communicate with each other?

Big old trees - dubbed 'mother trees' - are hubs in a mycorrhizal fungal network (Source: Smileus/iStockphoto)

Surprisingly, the answer is yes.

They might seem like the strong, tall and silent type, but trees actually communicate with each other.

Forest ecologist Dr Suzanne Simard, from the University of British Colombia, studies a type of fungi that forms underground communication networks between trees in North American forests.

Big old trees — dubbed 'mother trees' — are hubs in this mycorrhizal fungal network, playing a key role in supporting other trees in the forest, especially their offspring.

"If you're a mother and you have children, you recognise your children and you treat them in certain ways. We're finding that trees will do the same thing. They'll adjust their competitive behaviour to make room for their own kin and they send those signals through mycorrhizal networks," says Simard.

"We found that the biggest oldest trees had more connections to other trees than smaller trees. It stands to reason because they have more root systems," she says.

"So when a seedling establishes on the forest floor, if it's near one of these mother trees it just links into that network and accesses that huge resource network."

Sharing resources

Fungal networks don't just operate between related trees, but also between trees of different species in the same native community, says Simard.

In a landmark experiment, published in a 1997 issue of Nature, Simard used radioisotopes to trace carbon, nitrogen and water moving between a Douglas fir and a paper birch tree, which are both native to the inland forests of British Colombia.

When she shaded one tree, carbon-based sugars would flow into it from the other tree.
So rather than competing for resources, these two trees were using fungal networks to share them, says Simard.

In another study, Simard and her graduate student showed every tree in a 30 by 30-metre forest stand was connected to every other tree, with an estimated 250 to 300 trees being connected together in this single forest stand.

Defence signals

Other evidence shows trees use fungal networks to warn their neighbours about impending attacks from pests.

"When trees are attacked, they increase their defence against the invaders by upregulating their defence genes to make defence enzymes," says Simard.

"Research suggests they also send chemical signals down into their roots through their mycorrhizal networks to their neighbours, which then detect these signals and upregulate their own defence genes."

Lab studies have recorded defence signals travelling between trees in as little as six hours, says Simard.

She says when fungal networks are intact they allow a greater diversity of trees, each with their own strengths and weaknesses, to survive in the forest.

This diversity is the basis for forests that are resilient to disease, pests and climate change, says Simard.

Above-ground communication

Plant physiologist Professor Hans Lambers of the University of Western Australia says scientists have known for 20 or 30 years that plants communicate by giving off chemicals above ground.

The classic example is the release of volatile chemicals by plants that are attacked by pests. These chemicals are picked up by neighbouring plants which are then forewarned to defend themselves from the pests.

"The neighbours must sense those volatiles, and then respond by accumulating the chemicals that deter the attackers," says Lambers.

Above-ground chemicals can also attract predators that eat pests, and more recently this chemical communication has also been found to occur below ground, says Lambers.

But whether mycorrhizal fungi networks are used or not depends on the particular ecosystem.

Australian ecosystems

The Western Australian ecosystems, where Lambers works, are dominated by banksias, grevilleas and hakeas that on don't rely on mycorrhizal fungi.

However, eucalypt forests do have mycorrhizal fungal networks, says fungal ecologist Professor Ian Anderson of the University of Western Sydney, although no research has been done looking at their function.

"No-one's actually shown that an interconnected network is transferring carbon and nitrogen," he says. "It's a really under-researched area."

Anderson suspects fungal networks would be playing an even more important role in eucalypt forests than North American forests given their soils have much lower nutrients.

"I think these mycorrhizal networks have an even greater potential than what Suzanne Simard has shown," he says.

Implications for old-growth forests

Simard says her findings have implications for forestry practices that target old-growth trees.
"We need to leave these legacy trees and let them send their messages into the soil to surrounding plants," she says.

"This will help the recovery of forests following disturbance such as logging or fire."

Conserving fungal networks that help forests recover from disturbance could also prevent invasions by exotic species, which often compete with the endemic networks, she believes.

Dr Suzanne Simard, Professor Ian Anderson and Professor Hans Lambers spoke with Anna Salleh

Discovery of ancient stone tools in Kenya dating back 3.3 million years challenges story of mankind

The stone tools were discovered during the process of excavation at the Lomekwi 3 site in Kenya.

Anthropologists say the discovery of stone tools found in north-west Kenya dating back 3.3 million years challenges the mainstream story of mankind. 

Found in desert badlands near Lake Turkana, the tools include sharp-edged flakes that could have been used for cutting meat from animal carcasses and rudimentary hammers perhaps used to pound open nuts or tubers.

They are 700,000 years older than any other such stone tools ever found.

"The tools we have unearthed are the very first fossil traces of techniques bequeathed by our hominin ancestors 3.3 million years ago," said French researcher Sonia Harmand of New York's Stony Brook University.

"Our discovery also refutes the long-standing theory that Homo habilis was the first maker of tools."
Tool-making, like fire-making and farming, is considered a key moment in the ascent of humans.

The theory is that tools emerged to help hominins — the term for modern and extinct species of humans — butcher animals, unlocking protein that in turn helped the evolution of bigger brains.

But crafting a tool, by hitting a stone with another stone, requires conceptual and motor skills.
Until now, these were thought to be beyond the ape-like hominins who lived before habilis, whose "handy man" name comes from his apparent dexterity.

Habilis, bigger-brained than previous hominins and an ancestor of Homo sapiens, lived between roughly 2.8 million and 1.5 million years ago. The earliest tools in the Habilis era date from around 2.6 million years ago.

The tool discovery was made in the Nachukui Formation, a remote site in scrublands west of Lake Turkana that has yielded a series of remarkable finds since the mid-1980s.

It came through a stroke of luck, when Ms Harmand and her colleague Jason Lewis went on a scouting trip one morning in July 2011 and got lost.

Seeking their way back, they climbed a hill to get a better view and got a strange feeling "that something was special about this particular place".

With the help of a local tribesman, they explored craggy outcrops which yielded the first of these ancient treasures.

The haul, described in the journal Nature, comprises 149 artefacts, from stone cores and flakes to rocks used for hammering.

The stones were found just above a layer of volcanic ash dated through argon isotopes to about 3.3 million years ago.

This estimate was confirmed by measuring telltale shifts in Earth's magnetic fields in iron-bearing minerals in sediment where the tools were found.

Geological goldmine uncovered after Tasmanian lake drained

A view of the southern half of Lake Rowallan shortly after it was drained in late February.

1 billion year old Precambrian sedimentary rocks exposed at Lake Rowallan that were deformed and metamorphosed during the Cambrian collision (510 million years ago).

By Emilie Gramenz

Geologists have been taking advantage of a "once in a lifetime" opportunity to study ancient rock formations after a lake in the Tasmania's north was drained to reveal a Precambrian site.

Hydro Tasmania's Lake Rowallan, east of Cradle Mountain, was drained earlier this year as part of an upgrade to the Rowallan power station.

The Precambrian rock formations that were exposed are about one billion years old and have not been visible in 20,000 years.

University of Tasmania researcher Dr Rob Scott said the formations were last exposed during the ice age.

"The Precambrian rocks exposed... are [the result of] arguably the biggest and most significant geological event to have ever affected the state," he said.

Dr Scott said geology researchers were studying the deformation and metamorphic history of the rocks.

"What we can learn in Tasmania has implications for the geological development of the whole of eastern Australia at this time, but we have the advantage of being able to obtain hard data to help us understand exactly what happened," he said.

The Precambrian era - the earliest geological age - covers the bulk of Earth's history.

Scientists have only a small window to study the Lake Rowallan formations with Hydro Tasmania planning to refill the lake when upgrades to its infrastructure are complete.

Tuesday, May 12, 2015

A volcano or a meteor impact: What created this large mysterious Siberian crater?

Having an official task to draw up a geological map of the region, a young geologist ended up running into something so unique, outstanding and mysterious that it would still puzzle scientists more than six decades later – the Patomskiy Crater. A host of theories have been put forward in the intervening years: that the crater was created by an ancient civilization, or by prisoners at a top secret Stalin labor camp, or by volcanic activity, or by a meteorite, or by an underground hydrogen explosion, or by a UFO. And even more tantalizing: by two UFOs. Stories have been handed down by native people – who knew about the ‘cursed crater’ long before Kolpakov revealed it to the outside world. Among these accounts, were warnings that this ‘Devil’s Place’ was dangerous to humans. Questions remain unanswered about a phenomenon that has been called ‘The Most Mysterious Place in Russia.’ For example, why don’t trees grow on the side of the cone-like structure? Radiation levels are low now, but there is evidence they were once very high: why? In August 1949, when Kolpakov reached the very north of Irkutsk region, local Yakut people told him a story about an ‘evil’ place, hidden in the woods. They called it the Fire Eagle Nest, and according to them even the deer didn’t dare to go close to it. Locals told a lot of legends about it, warning people would suddenly start feeling unwell or even disappear, some to be found dead later, some never to be found. As recently as 2005, indeed, the head of a mission to the crater died suddenly within several kilometers of it. Legends didn’t scare Kolpakov back in 1949 but what he witnessed in a distance when he climbed up the hill was shocking.

What pushed up this massive mountain of rocks from the earth? ‘When I first saw the crater I thought that I’d gone crazy because of the heat,’ he noted. ‘And indeed a perfectly shaped mount of a size of a 25-storey building with a chopped off top sitting in the middle of the woods was quite an unexpected discovery. Since the discovery of this mysterious place, later named Patomskiy crater, scientists came up with widely differing theories of its origin: among them, an unknown underground explosion to the fall from space of a mysterious super dense substance unknown to man. Or even the UFO. But not a single one of these theories could fully explain the anomalies of the crater and the processes that still go on inside it. Later, other scientists, namely the geologist Alexander Portnov, came to the same conclusion, arguing that it could easily be former by a piece of space rock that sliced off the famous Tunguska meteoroid that exploded over Krasnoyarsk region, to the west of Patomskiy Crater, in 1908. Another early explanation was that the crater had volcanic origin. The shape superficially suggested this. Amateurs looking at it might see this as a probable theory. They may yet be right. “My NTV quote was a while ago, and since that time we’ve made a number of experiments and analyses that showed that most likely it is a volcano. Yes, the only one like this on this territory,” he said. “It is not a typical lava volcano, but just at some point gas exploded there.” Of course, there are many strange things still about the crater. There is no unified, definite consensus yet about it. Together with geomorphologists we have decided that it is the most likely version.

The strange thing that doesn’t fit the theory, however, is that if it was a gas explosion, it would not have raised the temperature. And there for a while the process of surface heating was certainly going on, there was an increased temperature level. ‘So the hypothesis is quite approximate still, but I do think that geomorphologists opinion is the most correct of all, that it is a gas volcano. “It also shows the typical ways of rising for the gas volcano – when gas keeps gathering inside the chamber, then there is an explosion that rises the ground, and gas starts gathering again. Then another explosion, and again the ground rises.” Alexander Pospeev, a doctor of geological and mineralogical sciences, insists the explanation is more prosaic, and less extra-terrestrial. “Even now, the origin of the crater is not discovered, but we can say for sure that it has the earthly origin,” he stated. “It could be caused by the underground release of some fluids such as hydrogen. Maybe some other fluid, that’s what we do not know exactly. But studies have now shown that there is no object like the fragments of an asteroid or some metal object under the crater, as has been suggested.”

 –Siberian Times

Monday, May 11, 2015

The Mighty Zhemchug

In many continental shelves submarine canyons have been found carving deep fissures that stretch from near shore out to the deep sea edge of the shelf. There are a number of theories as to what carved these giant cracks into the shelves, but the most prominent one states that sediment transport carved these canyons. Sediment transport in the sea occurs primarily as underwater landslides of enormous masses of rock and sediment, usually triggered by turbulent waters during a storm, or ground movement from an earthquake. The depth at which the submarine canyons have been cut depends on the make up of the underlying rock – how susceptible it is to being carved – and how much, how often and how heavy the materials are that are transported downslope during an underwater landslide. It is also believed that some canyons were carved above ground, at a time when sea level was a mile or more lower than it is today. Those canyons that are now submerged may have once held rivers and waterfalls that carved the canyon walls, carrying the sediment and debris down into shallower sea.

The largest and deepest submarine canyon ever discovered is in the middle of the Bering Sea called the Zhemchug Canyon. It is deeper than the Grand Canyon (1.83 km deep) at 2.6km deep. Zhemchug Canyon is the largest submarine canyon in the world, based on drainage area (11,350 km2) and volume (5800 km3). Deep, cold, oxygen-rich waters well up from the deeps into the canyon, providing sustenance to an enormous array and variety of life forms.

China’s Atlantis of the East

A real life version of Atlantis can be found at the bottom of a man-made lake in China. In 1959, the Chinese Government decided that they wanted to build a new hydro-electric power station and so made the call to build a huge lake in the Eastern Provence of Zhejiang. The lake was built between the Five Lion Mountain and the ancient city of Shi Cheng (Lion City), that was flooded in order to make way for the power station. The city has been untouched for over 50 years. A dive team has recently rediscovered the remains of the city but there are now plans to turn it into a dive site. Incredibly, the dive team said that nearly every structure in Lion City was still intact, even after lying underwater for over half a century!

The city was “rediscovered” in 2001 when the Chinese government organised an expedition to see what might remain of the lost metropolis. Interest and exploration increased further in 2011, when the Chinese National Geography published some never-before-seen photographs and illustrations hypothesising what the small city, which measured about half a square kilometre, might have looked like in its heyday.

Expeditions and underwater photographs have revealed that the city had five entrance gates, as opposed to the traditional four – with two western-facing gates as well as gates in the other cardinal directions. The city’s wide streets also have 265 archways, featuring preserved stonework of lions, dragons, phoenixes and historical inscriptions, some of which date back as far as 1777; the city walls are believed to date back to the 16th Century.

Despite being underwater, Shicheng has remained well preserved; the water actually protects it from wind, rain and sun erosion. Today, advanced divers can get up close to the ruins with dive operators such as Big Blue and Zi Ao Diving Club, which run regular dives between April and November.

Since the ruins have yet to be fully mapped, the dive is still considered “Exploratory” and is limited to divers with deep water, night and buoyancy experience. 

Thursday, May 7, 2015

Himalayan rivers and snow from the space station

(Source: NASA)

As the International Space Station flew 418 kilometres above the Himalaya Mountains, the crew snapped this photograph of the snow-capped panorama unfolding near the China-India border.

This image taken on April 8, 2015 - just over two weeks before the magnitude 7.9 earthquake hit nearby Nepal - shows the foothills of one of the main ranges of the Himalayas, where peaks cast strong evening shadows on the snow.

The mountains in this image reach altitudes of 5200 metres. Other peaks just beyond the upper edge of the image reach even higher altitudes of more than 6500 metres.

The flat areas at the base of the mountains are ancient alluvial fans, filled with sediment eroded from the high mountains over millions of years.

Snow cover highlights these strikingly smooth surfaces, which are cut through by a trellis-like network of gullies casting sinuous shadows.

The large river on the right of this scene has cut a 500-metre-deep canyon.

Although the rivers in this image drain northward from the Himalayas, they ultimately flow back to the south, accumulating in the Sutlej River (out of shot) which passes through the mountains toward the lowlands of Pakistan and, finally, empties out into the Arabian Sea.

The Himalayan Mountains are among the youngest mountain ranges on the planet, and were formed by the collision of the Indian and Eurasian tectonic plates along a 2400 kilometre arc which reaches its greatest elevation of 8848 metres at Mount Everest.

The Indian plate is continuing to drive horizontally beneath the Tibetan Plateau at a rate of about 67 millimetres per year, creating uplift in the Himalayas of about five millimetres every year and causing occasional large earthquakes such as the recent Nepalese quake.

EARTH IMAGE by Stuart Gary