Dwindling Green Pastures, Not Hunting, May Have Killed Off the Mammoth

A massive reduction in grasslands and the spread of forests may have been the primary cause of the decline of mammals such as the woolly mammoth, woolly rhino and cave lion, according to Durham University scientists.

The findings of the new study challenge the theory that human beings were the primary cause of the extinction of mammals through hunting, competition for land and increased pressure on habitats.

The research is part of the most comprehensive study to date of Northern Hemisphere climate and vegetation during and after the height of the last Ice Age, 21,000 years ago. It shows that, over a huge part of the Earth’s surface, there was a massive decline in the productivity and extent of grasslands due to climatic warming and the spread of forests.

These habitat changes made grazing much more difficult for large mammals and dramatically reduced the amount of food available for them. The changes in grassland quality and availability coincided with increases in the distribution and abundance of modern man, Homo sapiens, ensuring a time of wide-scale upheaval for herbivorous mammals and other mammals that preyed on them.

The decrease in productivity and extent of grassland is likely to have been the major contributor to the extinction of many large mammals across most of northern Eurasia and north-western North America by about 11,400 years ago, the onset of the present warm interglacial period. Although some species held on for several thousand years longer in very limited localities, their fate had effectively been sealed.

Professor Brian Huntley, from the School of Biological and Biomedical Sciences at Durham University, said: “Woolly mammoths retreated to northern Siberia 14,000 years ago whereas they had roamed and munched their way across many parts of Europe, including the UK, for most of the previous 100,000 years or more.

“The change from productive grasslands across large areas of northern Eurasia, Alaska and Yukon to less productive tundra-like habitats had a huge effect on many species, particularly on the large herbivores like the woolly rhinoceros and woolly mammoth. Mammoths and other mega-mammals found it increasingly difficult to find food.

“We believe that the loss of food supplies from productive grasslands was the major contributing factor to the extinction of these mega-mammals.”

The Durham University-led team, including scientists from The Natural History Museum, London; Lund University, Sweden, and Bristol University, publish their results in the scientific journal, Quaternary Science Reviews.

Their study, funded by the Natural Environment Research Council (NERC), looked at ancient pollen records and they also simulated developments in vegetation and habitat linked to climatic change, during and following the last glacial stage.

The team looked at results for a vast geographic area including Eurasia (Europe and northern Asia) and the area of the Bering land bridge that connected Alaska (USA) and the Yukon (Canada) to Siberia, Russia at the height of the last glacial.

They found the post-glacial warming of the planet coupled with an associated change to a moister climate and with increased levels of carbon dioxide in the atmosphere, resulted in the proliferation of trees and the subsequent decline in grasslands — the staple diet and fodder of large herbivores. The decline in herbivores had knock-on effects for other parts of the food chain.

Different theories exist for the cause of the extinction of mega-species like the mammoth. The rise of modern man, Homo sapiens, is cited by some as a potential cause.

Environmental changes have also been considered as a potential factor in the extinction of mega-herbivores such as the mammoth. This new evidence of massive habitat change linked to climatic change is, according to experts, a parable for modern times.

Prof Huntley said: “This was a time of major environmental change and losses of habitat that may have led to the extinction of herbivores and other mega-species that roamed many parts of the planet.

“This is a model for what may happen as a result of rapid climate change over the next century linked to human activity. It is food for thought in these times of global warming and human-induced habitat change. There may well be a lesson to learn.”

The big species today, such as elephants and rhinoceros, are the ones that are most likely to be the first affected by climate change and habitat pressure.

Five species formerly present in Europe, northern Asia, Alaska and Yukon that became globally extinct as grassland diminished:

1. Woolly mammoth
2. Cave lion
3. Giant deer
4. Woolly rhino
5. Cave bear

Five species that survived as grassland diminished:

1. Brown bear
2. Elk (moose)
3. Reindeer
4. Saiga antelope
5. Musk ox

Melting ice turns 10,000 walruses into landlubbers

For the third time in four years, a dearth of sea ice has forced walruses ashore in Alaska.

The lumbering marine mammals normally spend their summers resting on the ice as it floats north, making periodic dives to the ocean floor to forage for food. But this year, as in 2007 and 2009, a lack of ice in the eastern Chukchi Sea has driven thousands of walruses to congregate on land instead.

Officials with the U.S. Geological Survey and the Fish and Wildlife Service estimate that at least 10,000 animals have gathered in a dense clump at Point Lay, Alaska.

“Our biggest concern right now is stampeding,” said Bruce Woods, a spokesman for the Fish and Wildlife Service’s Alaska regional office. “That’s the big risk posed to these animals.”

That’s because the intensely social — but easily spooked — animals have congregated in numbers that dwarf their normal groupings of up to 500 animals.

The risk of injury and death is greatest for the youngest animals, which are dwarfed by adult female walruses that weigh about 1 ton each.

Last year, when walruses sought shelter on the shore of Icy Cape, Alaska, many of the 131 animals that were trampled to death there were juveniles, USGS found. Similarly deadly stampedes have also been reported in Russia in recent years (ClimateWire, Aug. 10).

Concerns about a stampede

So far this year, there is no evidence of any stampedes at Point Lay, and federal officials are trying to keep it that way. FWS is counseling aircraft traveling through the area to maintain a minimum altitude of 1,500 feet and a lateral distance of a half-mile away from the animals. The agency is also asking ships to maintain a half-mile “buffer zone” from the coast.

News of the unusual walrus behavior comes as FWS considers extending Endangered Species Act protection to the animals. The agency has until January to decide whether affording walruses some degree of protection is warranted.

Chad Jay, a USGS research ecologist whose work includes tagging and tracking walruses, said it appears the animals started to come ashore late last month.

“They were using an area called Hannah Shoals offshore for a number of weeks, but that little bit of ice disappeared, as well,” he said. “We had several animals move west and into Russian waters and find some ice over there, but quite a few animals have come to shore in Alaska.”

USGS researchers had suspected the animals might shelter on shore again this year, since Arctic sea ice has hovered near the historic summer low set in 2007.

Jay said scientists had camped at Icy Cape, where walruses came shore in 2007 and 2009, waiting to observe and tag animals. But the walruses surprised them by sheltering at Point Lay, about 50 miles south.

Bleak future for ice-loving tuskers

“This is the third time in the last four years that this has happened, and we’re still learning and looking for patterns,” Jay said. “Anything could have happened. In 2008, there was enough ice that stayed over the [continental] shelf that they never did come ashore, but we were kind of betting the odds they would come to shore again this year.”

Scientists aren’t sure how long the walruses will remain at Point Lay. But what is even less clear to them is how the walruses will fare over the long term, with many models projecting the Arctic could see ice-free summers by 2040.

At USGS, Jay and his colleagues are increasing the number of walruses they track with radio collars. They’ve also begun studies to determine whether near-shore areas can provide sufficient food and habitat if the gregarious animals come ashore year after year.

One of their initial studies, published last week, found “a clear trend of worsening conditions” for the animals through the end of this century. The USGS scientists say that 22 percent of the Arctic’s walruses could be classified as “vulnerable, rare or extirpated” by 2050, a fraction that rises to 40 percent by 2095.

Agropolis: The Future of Urban Agriculture?

Last week at the Nordic Exceptional Trendshop 2010, held in Denmark, one presentation  took urban agriculture to the next level. A collaboration with NASA, you might even say it launched urban agriculture out of this world, and into the future.The idea is called Agropolis, a combination grocery store, restaurant, and farm all in one building, employing the most advanced technologies in hydroponic, aeroponic, and aquaponic farming.

As it stands, Agropolis is still just a mere idea, with little more than some cool graphics to back it up. But regardless, Agropolis ushers forth a new wave of thinking about urban food systems.The team behind the Agropolis concept proposes that this new generation of store would be an ecosystem  unto itself, a finely tuned orchestra of parts in balance, that would not only be totally environmentally sustainably and friendly, but also just plain producing the freshest food around.

But what would all these innovative, NASA-inspired state of the art hydroponics and other high-tech solutions look like in practice? According to the vision of Agropolis, a customer would walk into a store that is covered in green. Vegetables growing on the walls as far as the eye can see. And below the floors one would see tilapia swimming, working in tandem with vegetables in an aquaponic system. You would buy a tomato that was literally just picked, from a plant that you can see in front of you. The store would bring a whole new meaning to local, and one-up the notion of hyper local, since all the food available to eat or buy would have traveled zero miles from the farm to the store. At most, just a few steps.

It all sounds grand, and more than a little space-age. But the challenge given to the team that came up with Agropolis wasn’t entirely outside reality: Create a farm without relying on arable land. As the Earth’s healthy soil and other resources dwindle, it may not be out of the realm of possibility that a system like Agropolis be needed, particularly in urban areas. And while urban agriculture has come a long way, incorporating all kinds of creative and innovative ideas and technologies, in order to make it work on a large and global scale it may be time for something as futuristic and high-tech as Agropolis.

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