Forests absorb one-third of our fossil fuel emissions

Public release date: 9-Aug-2011
[ | E-mail | Share ]

Contact: Craig Macaulay
Pep.Canadell@csiro.au
61-262-465-631
CSIRO Australia

The world's established forests remove 2.4 billion tonnes of carbon per year from the atmosphere ? equivalent to one third of current annual fossil fuel emissions ? according to new research published today in the journal Science. This is the first time volumes of the greenhouse gas absorbed from the atmosphere by tropical, temperate and boreal forests have been so clearly identified.

"This is really a timely breakthrough with which we can now clearly demonstrate how forests and changes in landscape such as wildfire or forest regrowth impact the removal or release of atmospheric carbon dioxide (CO2)," says CSIRO co-author of the paper: A Large and Persistent Carbon Sink in the World's Forests, Dr Pep Canadell.

"What this research tells us is that forests play a much larger role as carbon sinks as a result of tree growth and forest expansion."

Dr Canadell, who is also the Executive Director of the Global Carbon Project, said the international research team combined data from forest inventories, models and satellites to construct a profile of forests as major regulators of atmospheric CO2.

In addition to the large carbon sink, he said scientists now know that deforestation is responsible for emitting 2.9 billion tonnes of carbon per year ? an exchange that had not been known in the past because of a lack of data. For comparison, total emissions from fossil fuels are currently above eight billion tonnes of carbon per year.Dr Canadell said emissions from deforestation are much larger than previously thought, suggesting that the potential benefits of avoiding deforestation through the United Nations-backed Reduced Emissions from Deforestation and Degradation (REDD) scheme, are much larger than previously appreciated.

The REDD scheme aims to formulate a financial value for the carbon stored in forests.

Dr Canadell said a surprising finding was the large capacity of tropical forest re-growth to remove atmospheric CO2. Regrowth takes place following the end of logging and slash-and-burn land clearing projects. and, to a lesser extent, when new forest plantations are planted.

"We estimate that tropical forest regrowth is removing an average of 1.6 billion tonnes of carbon per year. Unfortunately, some countries have not looked on forest regrowth as a component of REDD, and so are missing a very important opportunity to gain even further climate benefits from the conservation of forests.

"Combining the uptake by established and forest re-growth plus emissions from deforestation, the world's forests have a net effect on atmospheric CO2 equivalent to the removal of 1.1 billion tonnes of carbon every year.

"Carbon exchanges from tropical forests have the highest uncertainties in this analysis and this research has required a concerted effort to refine them to our best knowledge," Dr Canadell said.

[ | E-mail | Share ]
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

View the original article here

Fossil May Evict Archaeopteryx From Avian Family Tree

Chinese paleontologists reported in the current issue of the journal Nature that a previously unknown chicken-size 155-million-year-old dinosaur with feathers, named Xiaotingia zhengi, “challenges the centrality of Archaeopteryx in the transition to birds.”

Like so many fossil dinosaurs and other life from the late Jurassic period, Xiaotingia was found in Liaoning Province, a happy hunting ground for paleontologists. The skeleton was embedded in shale, along with the clear impressions of feathers. Scientists who studied the specimen said it was not as striking in appearance as several of the 10 known Archaeopteryx remains, but good enough apparently to contradict conventional wisdom about proto-birds.

The discovery team and other scientists emphasized that the new findings, if confirmed by additional research, would not undermine the prevailing theory that modern birds descended from dinosaurs. The question now is, if not Archaeopteryx, which of many feathered dinosaurs or dinosaurlike birds being found is closest to the first bird? Other assumptions about the early evolution of birds, they said, would also need to be re-evaluated.

Xing Xu and his colleagues at the Chinese Academy of Sciences in Beijing said that their examination of Xiaotingia, in comparison with more recognizably bird skeletons from the same period as well as the 150-million-year-old Archaeopteryx, showed that the new fossils fell short of a place in the avian family. Several of its anatomical traits, like the long and robust forelimbs once thought to be diagnostic of birds, were actually common to a group of dinosaurs known as deinonychosaurs.

Dr. Xu’s team concluded that “the most important result of our analysis” is that the anatomies of the Chinese specimen and Archaeopteryx were remarkably similar, meaning that both belonged to the lineage of the meat-eating deinonychosaurs, not the plant-eating early birds. In short, Archaeopteryx presumably was not an ancestral bird. The recent discovery of a tenth Archaeopteryx specimen “greatly improved our knowledge” of its similarities to the dinosaur group and its differences from birds, the paleontologists said.

Several scientists who were not involved in the research said they were not especially surprised by the findings.

“It may seem heretical to say that Archaeopteryx isn’t a bird, but this idea has surfaced occasionally since as far back as the 1940s,” Lawrence M. Witmer, a paleontologist at Ohio University, wrote in a commentary accompanying the journal article. “Moreover, there has been growing unease about the avian status of Archaeopteryx as, one by one, its ‘avian’ attributes (feathers, wishbone, three-fingered hand) started showing up in non-avian dinosaurs.”

Nor was this report likely to be the last word on the subject. The researchers themselves, among the leading dinosaur specialists in China, acknowledged that their interpretation was sure to be controversial. They conceded that some of their conclusions are “only weakly supported by the available data.” At such an early stage in the dinosaur-bird transition, distinctions among species were often subtle, or “rather messy affairs,” as Dr. Witmer said.

Scientists are expected to take another, deeper look at many feathered fossil animals that have been uncovered in China in the last 15 years. Several of these avian dinosaur species, including Epidexipteryx, Jeholornis and Sapeornis, may then take wing as the new early birds. And relentless fossil hunters are certain to turn up new species.

“This will be frustrating and exciting,” Dr. Witmer said in an interview, noting that — who knows? — the next discovery might tempt scientists to restore Archaeopteryx to its place in the proto-bird flock. “Some of these things may never be entirely conclusive,” he said. “It drives us nuts.”

Since “virtually all our notions about early avian evolution have previously been viewed through the lens of Archaeopteryx,” Dr. Witmer said, “the impact of losing Archaeopteryx from the avian clan is likely to rock the paleontological community for years to come.”

View the original article here

Fossil forensics reveals how wasps populated rotting dinosaur eggs

Public release date: 15-Jul-2011
[ | E-mail | Share ]

Contact: Dr. Emily Rayfield
publicity@palass.org
Wiley-Blackwell

Exceptionally preserved fossils of insect cocoons have allowed researchers in Argentina to describe how wasps played an important role in food webs devoted to consuming rotting dinosaur eggs. The research is published today (15th July) in the scientific journal Palaeontology.

The approximately 70 million year old eggs, from gigantic titanosaur sauropod dinosaurs were discovered in 1989 in the Patagonia region of Argentina, well known for yielding fossils of sauropod dinosaur eggs and even embryonic dinosaurs. Only recently it was discovered that one of the broken eggs contained tiny sausage-shaped structures, 2-3cm long and 1cm wide. The structures closely resembled fossilised insect cocoons, and were most similar in size and shape to the cocoons of some species of modern wasp.

There are many records of fossilised dinosaur eggs, and even several records of fossil cocoons, but, as author Dr Jorge Genise of the Museo Argentino de Ciencias Naturales states "this is the first time that these cocoons are found closely associated with an egg". Such a study of organismal behaviour (e.g. burrows, footprints) is known as ichnology.

The results indicate "that wasps probably participated in the food web, mostly composed of scavenging insects, which developed on the rotten egg". The make-up of carrion communities ? spiders, beetles and other creatures populating rotting organic matter ? is more familiar to us from the screens of crime scene investigation documentaries.

The numbers and different types of creatures indicate the length of deposition and the time since death. In this particular CSI, it appears that the dinosaur egg was broken by force, and subsequent fractures in the egg shell allowed scavenging creatures to feed upon the contents. At egg sizes of around 20cm, this represents a sizable amount of yolk! Other creatures later appeared to feed not upon the egg contents, but on the initial scavengers themselves. The wasps represent the top of the food web, and could have been feeding on insects or spiders gorging on rotting egg contents.

These scavengers also played an important role in cleaning up nest sites. Palaeontologists believe that some dinosaurs revisited nest sites year after year to lay new clutches of eggs. Carrion communities were essential to removing decaying material in advance of new nesting seasons. This new discovery gives us an insight into the murky world of insect communities that thrived at the feet of gigantic dinosaurs.

[ | E-mail | Share ]
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

View the original article here