Showing posts with label Extinctions. Show all posts

Written by fatih al-farahat in ,


Joern Fischer et al., PNAS 107 (2010), Tree decline and the future of Australian farmland biodiversity

Proceedings of the National Academy of Sciences (November 9, 2010; published online before print October 25, 2010), Vol. 107, No. 45, pp. 19597-19602; doi: 10.1073/pnas.1008476107

Tree decline and the future of Australian farmland biodiversity

  1. Joern Fischera,b,*, 
  2. Andre Zergerc, 
  3. Phil Gibbonsa, 
  4. Jenny Stotta and
  5. Bradley S. Lawd
+Author Affiliations
  1. aThe Fenner School of Environment and Society, Australian National University, Canberra ACT 0200, Australia;
  2. bDepartment of Sustainability Sciences, Leuphana University Lueneburg, 21335 Lueneburg, Germany;
  3. cCommonwealth Scientific and Industrial Research Organization Sustainable Ecosystems, Canberra ACT 2601, Australia; and
  4. dForest Science Centre, Industry and Investment NSW, Beecroft NSW 2119, Australia
  1. Edited by Harold A. Mooney, Stanford University, Stanford, CA, and approved September 30, 2010 (received for review June 15, 2010)

Abstract

Farmland biodiversity is greatly enhanced by the presence of trees. However, farmland trees are declining worldwide, including in North America, Central America, and parts of southern Europe. We show that tree decline and its likely consequences are particularly severe in Australia's temperate agricultural zone, which is a threatened ecoregion. Using field data on trees, remotely sensed imagery, and a demographic model for trees, we predict that by 2100, the number of trees on an average farm will contract to two-thirds of its present level. Statistical habitat models suggest that this tree decline will negatively affect many currently common animal species, with predicted declines in birds and bats of up to 50% by 2100. Declines were predicted for 24 of 32 bird species modeled and for all of six bat species modeled. Widespread declines in trees, birds, and bats may lead to a reduction in economically important ecosystem services such as shade provision for livestock and pest control. Moreover, many other species for which we have no empirical data also depend on trees, suggesting that fundamental changes in ecosystem functioning are likely. We conclude that Australia's temperate agricultural zone has crossed a threshold and no longer functions as a self-sustaining woodland ecosystem. A regime shift is occurring, with a woodland system deteriorating into a treeless pasture system. Management options exist to reverse tree decline, but new policy settings are required to encourage their widespread adoption.

Written by fatih al-farahat in


Adaptation and extinction in experimentally fragmented landscapes, PNAS (2010), by Sima Fakheran et al.

Proceedings of the National Academy of Sciences, published online before print October 18, 2010; doi:10.1073/pnas.1010846107

Adaptation and extinction in experimentally fragmented landscapes



  1. Sima Fakherana,1,2, 
  2. Cloé Paul-Victora,1,3, 
  3. Christian Heichingerb, 
  4. Bernhard Schmida, 
  5. Ueli Grossniklausb,4 and 
  6. Lindsay A. Turnbulla,4


Abstract

Competition and disturbance are potent ecological forces that shape evolutionary trajectories. These forces typically work in opposition: when disturbance is infrequent, densities are high and competition is intense. In contrast, frequent disturbance creates a low-density environment in which competition is weak and good dispersal essential. We exploited recent advances in genomic research to quantify the response to selection by these powerful ecological forces at the phenotypic and molecular genetic level in experimental landscapes. We grew the annual plant Arabidopsis thaliana in discrete patches embedded in a hostile matrix and varied the number and size of patches and the intensity of disturbance, by creating both static and dynamic landscapes. In static landscapes all patches were undisturbed, whereas in dynamic landscapes all patches were destroyed in each generation, forcing seeds to disperse to new locations. We measured the resulting changes in phenotypic, genetic, and genotypic diversity after five generations of selection. Simulations revealed that the observed loss of genetic diversity dwarfed that expected under drift, with dramatic diversity loss, particularly from dynamic landscapes. In line with ecological theory, static landscapes favored good competitors; however, competitive ability was linked to growth rate and not, as expected, to seed mass. In dynamic landscapes, there was strong selection for increased dispersal ability in the form of increased inflorescence height and reduced seed mass. The most competitive genotypes were almost eliminated from highly disturbed landscapes, raising concern over the impact of increased levels of human-induced disturbance in natural landscapes.



Link: http://www.pnas.org/content/early/2010/10/14/1010846107.abstract

Written by fatih al-farahat in


WWF: Tropics in Decline as Natural Resources Exhausted at Alarming Rate


Tropics in Decline as Natural Resources Exhausted at Alarming Rate



ScienceDaily (Oct. 18, 2010) — New analysis shows populations of tropical species are plummeting and humanity's demands on natural resources are sky-rocketing to 50 per cent more than the earth can sustain, reveals the 2010 edition of WWF's Living Planet Report -- the leading survey of the planet's health.



The biennial report, produced in collaboration with the Zoological Society of London and the Global Footprint Network, uses the global Living Planet Index as a measure of the health of almost 8,000 populations of more than 2,500 species. The global Index shows a decrease by 30% since 1970, with the tropics hardest hit showing a 60% decline in less than 40 years.
"There is an alarming rate of biodiversity loss in low-income, often tropical countries while the developed world is living in a false paradise, fuelled by excessive consumption and high carbon emissions," said Jim Leape, Director General of WWF International.
While the report shows some promising recovery by species' populations in temperate areas, thanks in part to greater conservation efforts and improvements in pollution and waste control, tracked populations of freshwater tropical species have fallen by nearly 70 per cent -- greater than any species' decline measured on land or in our oceans.
"Species are the foundation of ecosystems," said Jonathan Baillie, Conservation Programme Director with the Zoological Society of London. "Healthy ecosystems form the basis of all we have -- lose them and we destroy our life support system."
The Ecological Footprint, one of the indicators used in the report, shows that our demand on natural resources has doubled since 1966 and we're using the equivalent of 1.5 planets to support our activities. If we continue living beyond the Earth's limits, by 2030 we'll need the equivalent of two planets' productive capacity to meet our annual demands.
"The report shows that continuing of the current consumption trends would lead us to the point of no return," added Leape. "4.5 Earths would be required to support a global population living like an average resident of the of the US."
Carbon is a major culprit in driving the planet to ecological overdraft. An alarming 11-fold increase in our carbon footprint over the last five decades means carbon now accounts for more than half the global Ecological Footprint.
The top 10 countries with the biggest Ecological Footprint per person are the United Arab Emirates, Qatar, Denmark, Belgium, United States, Estonia, Canada, Australia, Kuwait and Ireland.
The 31 OECD countries, which include the world's richest economies, account for nearly 40% of the global footprint. While there are twice as many people living in BRIC countries -- Brazil, Russia, India and China -- as there are in OECD countries, the report shows the current rate of per-person footprint of the BRIC countries puts them on a trajectory to overtake the OECD bloc if they follow same development path.
"Countries that maintain high levels of resource dependence are putting their own economies at risk," said Mathis Wackernagel, President of the Global Footprint Network. "Those countries that are able to provide the highest quality of life on the lowest amount of ecological demand will not only serve the global interest, they will be the leaders in a resource-constrained world."
New analysis in the report also shows that the steepest decline in biodiversity falls in low-income countries, with a nearly 60 per cent decline in less than 40 years.
The biggest footprint is found in high-income countries, on average five times that of low-income countries, which suggests unsustainable consumption in wealthier nations rests largely on depleting the natural resources of poorer, often still resource rich tropical countries.
The Living Planet Report also shows that a high footprint and high level of consumption, which often comes at the cost of others, is not reflected in a higher level of development. The UN Human Development Index, which looks at life expectancy, income and educational attainment, can be high in countries with moderate footprint.
The Report outlines solutions needed to ensure the Earth can sustain a global population projected to pass nine billion in 2050, and points to choices in diet and energy consumption as critical to reducing footprint, as well as improved efforts to value and invest in our natural capital.
"The challenge posed by the Living Planet Report is clear," said Leape. "Somehow we need to find a way to meet the needs of a growing and increasingly prosperous population within the resources of this one planet. All of us have to find a way to make better choices in what we consume and how we produce and use energy."
More information about the report can be found at:

Written by fatih al-farahat in ,


Seth Borenstein: Melting sea ice forces walruses ashore in Alaska - September 13, 2010

Melting sea ice forces walruses ashore in Alaska
By SETH BORENSTEIN (AP) – 18 hours ago
WASHINGTON — Tens of thousands of walruses have come ashore in northwest Alaska because the sea ice they normally rest on has melted.
Federal scientists say this massive move to shore by walruses is unusual in the United States. But it has happened at least twice before, in 2007 and 2009. In those years Arctic sea ice also was at or near record low levels.
The population of walruses stretches "for one mile or more. This is just packed shoulder-to-shoulder," U.S. Geological Survey biologist Anthony Fischbach said in a telephone interview from Alaska. He estimated their number at tens of thousands.
Scientists with two federal agencies are most concerned about the one-ton female walruses stampeding and crushing each other and their smaller calves near Point Lay, Alaska, on the Chukchi Sea. The U.S. Fish and Wildlife Service is trying to change airplane flight patterns to avoid spooking the animals. Officials have also asked locals to be judicious about hunting, said agency spokesman Bruce Woods.
The federal government is in a year-long process to determine if walruses should be put on the endangered species list.
Fischbach said scientists don't know how long the walrus camp-out will last, but there should be enough food for all of them.
During normal summers, the males go off to play in the Bering Sea, while the females raise their young in the Chukchi. The females rest on sea ice and dive from it to the sea floor for clams and worms.
"When they no longer have a place to rest, they need to go some place and it's a long commute," Fischbach said. "This is directly related to the lack of sea ice."
Loss of sea ice in the Chukchi this summer has surprised scientists because last winter lots of old established sea ice floated into the region, said Mark Serreze, director of the National Snow and Ice Data Center in Boulder, Colo. But that has disappeared.
Although last year was a slight improvement over previous years, Serreze says there's been a long-term decline that he blames on global warming.
"We'll likely see more summers like this," he said. "There is no sign of Arctic recovery."
U.S. Geological Survey walrus research site:http://alaska.usgs.gov/science/biology/walrus/index.html
The National Snow and Ice Data Center: http://nsidc.org/arcticseaicenews/index.html

Written by fatih al-farahat in


Canada's muskoxen down 80% due to starvation caused by climate change (report "Extinction: It's Not Just For Polar Bears" lead author Shaye Wolf)

Warming Arctic pushes wildlife to the edge


by Rosslyn Beeby, Science and Environmental Reporter, The Canberra Times, September 14, 2010


The Arctic is warming at a rate almost twice the global average, triggering mass starvation of wildlife and a doubling of coastal erosion in some areas, a new report says.

An estimated 20,000 muskoxen starved to death in one year in northern Greenland and Canada as a result of a 50% increase in ''rain-on-snow events," according to a study by the Washington-based Centre for Biological Diversity and Care for the Wild International.

Because of warming temperatures, snowfalls are replaced by freezing rains that fall on snow, creating a hard ice crust that prevents the muskoxen breaking through to forage on moss and lichen below the snow. Canada has had an 80% decline in muskoxen in its high Arctic regions as a result of starvation.

The report, Extinction: It's Not Just for Polar Bears, examines the impact of climate change on 17 Arctic species ranging from the sea butterfly a tiny marine snail dubbed the potato chip of the sea because of its importance as a food source to whales, seals, birds and polar bears.

The centre's climate science director and report's lead author, conservation biologist Shaye Wolf, said some Arctic species had already experienced widespread die-offs and population declines after losing food sources and habitat. Others faced threats from extreme weather events or new pressure from predators, parasites and pathogens moving northward.

''The polar bear is the best-known victim of rapid melting in the Arctic, but if we don't slash greenhouse pollution, many more creatures will follow it down the path to extinction,'' Dr Wolf said.

Loss of Arctic sea-ice is forcing female walruses to calve on land, where the pups are vulnerable to predators and risk being crushed or trampled when walrus colonies are alarmed by predators and adults stampede to the water.

The report estimates up to 4,000 pups were killed during a recent walrus stampede in Siberia.

Poor snow conditions have also affected lemming populations in Norway, leading to breeding failures and a dramatic decline in Arctic foxes which rely on a seasonal peak in lemmings numbers to feed their young.

Dr Wolf said red foxes were also moving northwards, competing with the smaller Arctic foxes for food and habitat.

For more on this story, including details of further impacts of warming on the region, see the print edition of today's Canberra Times.

Written by fatih al-farahat in


John Alroy: Earth is 'in the middle of mass extinction.' Rolling the dice: Current mass extinction will have unpredictable consequences

Rolling the dice with evolution: Mass extinction will have unpredictable consequences

3 September 2010

New research by Macquarie University palaeobiologist, Dr John Alroy, predicts major changes to the rules of evolution as we understand them now. Those changes will have serious consequences for future biodiversity because no one can predict which groups will come to dominate after the current mass extinction.
John Alroy. Image by David Roth Photography.
Alroy said today's extinction is due to a range of human behaviours and activities coupled with the effects of climate change. His findings were published this week in the international journal Science.

Alroy, who works in the Department of Biological Sciences at the University, undertook his study while at University of California, Santa Barbara, using the massive Paleobiology Database, which compiles data from nearly 100,000 fossil collections worldwide. He tracked the fate of major groups of marine animals throughout the fossil record and during the Earth's most massive extinction event, which occurred 250 million years ago.

He concludes that the rules governing diversity of these major groups we have assumed to be invariant have actually changed through geological time. Thus, a group's average rate of diversification or branching into new species in the past is not a good predictor of how well it will fare after a mass extinction event.

Alroy's findings indicate that as a result of a range of factors, the major extinction event currently underway will be much more severe than has been seen in most other major periods of mass extinction. Alroy notes there have been only three mass extinctions on the level of the current one in the last half billion years.

Organisms that might have adapted in the past may not be able to this time, he said.

"You may end up with a dramatically altered sea floor because of changes in the dominance of major groups. That is, the extinction occurring now will overturn the balance of the marine groups."

When there is a major mass extinction, it's not just a temporary drop in richness of species, he said.
Alroy likens what is happening now to rolling the dice with evolution.

"What's worrisome is that some groups permanently become dominant that otherwise wouldn't have. So by causing this extinction, we are taking a big gamble on what kind of species will be around in the future. We don't know how it will turn out. People don't realise that there will be very unpredictable consequences."

Link:  http://mq.edu.au/newsroom/control.php?page=story&item=4229