Detect Extensive Drought Impact On Amazon Forests

WASHINGTON -- A new NASA-funded study has revealed widespread reductions in the greenness of Amazon forests caused by last year's record-breaking drought.

"The greenness levels of Amazonian vegetation -- a measure of its health -- decreased dramatically over an area more than three and one-half times the size of Texas," said Liang Xu, the study's lead author from Boston University. "It did not recover to normal levels, even after the drought ended in late October 2010."

The drought sensitivity of Amazon rainforests is a subject of intense study. Computer models predict a changing climate with warmer temperatures and altered rainfall patterns could cause moisture stress leading to rainforests being replaced by grasslands or woody savannas. This would release the carbon stored in rotting wood into the atmosphere, which could accelerate global warming. The United Nations' Intergovernmental Panel on Climate Change has warned similar droughts could be more frequent in the Amazon region in the future.

The comprehensive study was prepared by an international team of scientists using more than a decade's worth of satellite data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measuring Mission (TRMM). Analysis of these data produced detailed maps of vegetation greenness declines from the 2010 drought. The study has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The authors first developed maps of drought-affected areas using thresholds of below-average rainfall as a guide. Next, they identified affected vegetation using two different greenness indexes as surrogates for green leaf area and physiological functioning.
The maps show the 2010 drought reduced the greenness of approximately 965,000 square miles of vegetation in the Amazon -- more than four times the area affected by the last severe drought in 2005.

"The MODIS vegetation greenness data suggest a more widespread, severe and long-lasting impact to Amazonian vegetation than what can be inferred based solely on rainfall data," said Arindam Samanta, a co-lead author from Atmospheric and Environmental Research Inc. in Lexington, Mass.

The severity of the 2010 drought also was seen in records of water levels in rivers across the Amazon basin, including the Rio Negro which represents rainfall levels over the entire western Amazon. Water levels started to fall in August 2010, reaching record low levels in late October. Water levels only began to rise with the arrival of rains later that winter.

"Last year was the driest year on record based on 109 years of Rio Negro water level data at the Manaus harbor," said Marcos Costa, co-author from the Federal University in Vicosa, Brazil. "For comparison, the lowest level during the so-called once-in-a-century drought in 2005 was only eighth lowest."

As anecdotal reports of a severe drought began to appear in the news media last summer, the authors started near-real time processing of massive amounts of satellite data. They used a new capability, the NASA Earth Exchange (NEX), built for the NASA Advanced Supercomputer facility at the agency's Ames Research Center in Moffett Field, Calif. NEX is a collaborative supercomputing environment that brings together data, models and computing resources.

Space Station Crew Launches from Birthplace of Human Spaceflight

WASHINGTON -- One week shy of the 50th anniversary of the first human spaceflight, NASA astronaut Ron Garan and Russian cosmonauts Andrey Borisenko and Alexander Samokutyaev launched to the International Space Station at 6:18 p.m. EDT Monday (4:18 a.m. local time, April 5) from the Baikonur Cosmodrome in Kazakhstan.

The Soyuz rocket that lifted Garan, Borisenko and Samokutyaev into orbit was decorated with Yuri Gagarin's name. The mission lifted off from the same launch pad used April 12, 1961, when Gagarin became the first human to journey into space.

The crew is scheduled to dock its Soyuz TMA-21 spacecraft to the station's Poisk port at 7:18 p.m. on Wednesday, April 6. The crew members will join Expedition 27 Commander Dmitry Kondratyev and Flight Engineers Cady Coleman of NASA and Paolo Nespoli of the European Space Agency, who have been aboard the orbiting laboratory since December 2010.

Scientists Find New Type Of Mineral In Historic Meteorite

HOUSTON -- NASA and co-researchers from the United States, South Korea and Japan have found a new mineral named "Wassonite" in one of the most historically significant meteorites recovered in Antarctica in December 1969.

The new mineral was discovered within the meteorite officially designated Yamato 691 enstatite chondrite. The meteorite was discovered the same year as other landmark meteorites Allende and Murchison and the return of the first Apollo lunar samples. The study of meteorites helps define our understanding of the formation and history of the solar system.

The meteorite likely may have originated from an asteroid orbiting between Mars and Jupiter. Wassonite is among the tiniest, yet most important, minerals identified in the 4.5-billion-year-old sample. The research team, headed by NASA space scientist Keiko Nakamura-Messenger, added the mineral to the list of 4,500 officially approved by the International Mineralogical Association.

"Wassonite is a mineral formed from only two elements, sulfur and titanium, yet it possesses a unique crystal structure that has not been previously observed in nature," said Nakamura-Messenger.

In 1969, members of the Japanese Antarctic Research Expedition discovered nine meteorites on the blue ice field of the Yamato Mountains in Antarctica. This was the first significant recovery of Antarctic meteorites and represented samples of several different types. As a result, the United States and Japan conducted systematic follow-up searches for meteorites in Antarctica that recovered more than 40,000 specimens, including extremely rare Martian and lunar meteorites.

Researchers found Wassonite surrounded by additional unknown minerals that are being investigated. The mineral is less than one-hundredth the width of a human hair or 50x450 nanometers. It would have been impossible to discover without NASA's transmission electron microscope, which is capable of isolating the Wassonite grains and determining their chemical composition and atomic structure.

"More secrets of the universe can be revealed from these specimens using 21st century nano-technology," said Nakamura-Messenger.

The new mineral's name was approved by the International Mineralogical Association. It honors John T. Wasson, professor at the University of California, Los Angeles (UCLA). Wasson is known for his achievements across a broad swath of meteorite and impact research, including the use of neutron activation data to classify meteorites and to formulate models for the chemical makeup of bulk chondrites.

"Meteorites, and the minerals within them, are windows to the formation of our solar system," said Lindsay Keller, space scientist at NASA's Johnson Space Center in Houston. Keller is the co-discoverer and principal investigator of the microscope used to analyze the Wassonite crystals. "Through these kinds of studies we can learn about the conditions that existed and the processes that were occurring then."

Johnson's advanced work in nanotechnology is part of the center's Astromaterial Research and Exploration Science Directorate. It is currently the location for celestial materials that would be returned to Earth from spacecraft. The facility collaborates with industry, academic and international organizations.

"The beauty of this research is that it really demonstrates how the Johnson Space Center has become a pre-eminent leader in the field of nanoscale analysis," said Simon Clemett, a space scientist at Johnson and co-discoverer of the new mineral. "In the words of the great English poet William Blake, we are now able 'to see the world in a grain of sand'.

Collaborators in the discovery of the new mineral include Clemett, Keller and Zia Rahman in the Astromaterials Research and Exploration Science Directorate at Johnson; Alan Rubin from UCLA; Byeon-Gak Choi from Seoul National University, South Korea; Shouliang Zhang from the Lunar and Planetary Institute in Houston; and Katsunari Oikawa from Tohoku University, Japan.

NASA Kepler Mission Update

University of Sydney astrophysicists are behind a major breakthrough in the study of the senior citizens of our galaxy: stars known as Red Giants. Using high precision brightness measurements taken by the Kepler spacecraft, scientists have been able to distinguish profound differences inside the cores of stars that otherwise look the same on the surface.

The discovery, published in the latest edition of the journal Nature and made possible by observations using NASA's powerful Kepler space telescope, is shedding new light on the evolution of stars, including our own sun.

The paper's lead author, the University of Sydney's Professor Tim Bedding, explains, "Red giants are evolved stars that have exhausted the supply of hydrogen in their cores that powers nuclear fusion, and instead burn hydrogen in a surrounding shell. Towards the end of their lives, red giants begin burning the helium in their cores."

The Kepler space telescope has allowed Professor Bedding and colleagues to continuously study starlight from hundreds of red giants at an unprecedented level of precision for nearly a year, opening up a window into the stars' cores.

"The changes in brightness at a star's surface is a result of turbulent motions inside that cause continuous star-quakes, creating sound waves that travel down through the interior and back to the surface," Professor Bedding said.

"Under the right conditions, these waves interact with other waves trapped inside the star's helium core. It is these 'mixed' oscillation modes that are the key to understanding a star's particular life stage. By carefully measuring very subtle features of the oscillations in a star's brightness, we can see that some stars have run out of hydrogen in the center and are now burning helium, and are therefore at a later stage of life."

Astronomer Travis Metcalfe of the US National Center for Atmospheric Research, in a companion piece in the same Nature issue which highlights the discovery's significance, compares red giants to Hollywood stars, whose age is not always obvious from the surface. "During certain phases in a star's life, its size and brightness are remarkably constant, even while profound transformations are taking place deep inside."

Professor Bedding and his colleagues work in an expanding field called asteroseismology. "In the same way that geologists use earthquakes to explore Earth's interior, we use star quakes to explore the internal structure of stars," he explained.

Professor Bedding said: "We are very excited about the results. We had some idea from theoretical models that these subtle oscillation patterns would be there, but this confirms our models. It allows us to tell red giants apart, and we will be able to compare the fraction of stars that are at the different stages of evolution in a way that we couldn't before."

Daniel Huber, a PhD student working with Professor Bedding, added: "This shows how wonderful the Kepler satellite really is. The main aim of the telescope was to find Earth-sized planets that could be habitable, but it has also provided us with a great opportunity to improve our understanding of stars."

Hydrogen -- Green Revolution

Host Lisa Van Pay meets with NSF-funded scientists Yang-Shao Horn and Yogi Surendranath at the Massachusetts Institute of Technology as they take on the hydrogen energy challenge. Hydrogen bonds are an extremely efficient way to store energy, and scientists would like to capture this energy to power all sorts of things--from cars to laptops.

Lord of the Tree Rings

Trees are outstanding historians. In fact, scientists dating back to Leonardo da Vinci recognized the value of trees. While others had figured out that you could determine the age of a tree by counting its growth rings, da Vinci went beyond that basic knowledge.
"He was a genius and realized also that the width of those growth rings carried information about the environmental conditions during each year the rings were formed," says David Stahle, director of the Tree Ring Laboratory at the University of Arkansas.
"So, he really anticipated the entire science of dendrochronology using annual growth rings from trees to infer past environmental variability, especially climate variability," continues Stahle, a professor in the university's Geosciences Department. "The time series of fat rings versus skinny rings is telling you about the history of wet years versus dry years."
Along with colleagues from the National Laboratory of Dendrochronology at the Mexican Forest Research Institute, Stahle collects tree-ring samples from remote forests, far from human influence. With support from the National Science Foundation (NSF), Stahle is now developing tree-ring records of Mexico's climate variability.
"Mexico has suffered persistent drought and we've done research on this using both the instrumental record and tree-ring reconstructions. One notion is that this 21st century drought may be being aggravated by human activity, both at the global scale and at the regional scale due to land surface changes," explains Stahle. "Not only is Mexico vulnerable to water availability, but her hydroelectric power supply system is also vulnerable to climate variations and drought. Mexico has had a notorious history of drought that has interacted with food supply availability, famine and disease, and has resulted in catastrophic population loss in the colonial history of that country."
So how do scientists extract a tree-ring core as thick as a pencil without harming the tree?
The key is a tool called a Swedish increment borer, invented more than 100 years ago to test the growth rate of living trees. It's basically a long, hollow steel auger. "This increment borer can be screwed into the center of the tree and it extrudes a core inside the long drill bit. You then remove the core from the auger with a long thin steel foil called an extraction spoon," Stahle says.
It does take practice and a little elbow grease! But, if done properly there's no permanent damage to the tree. In addition to offering a history of weather, these tree rings also offer some insight into how our ancestors lived, such as the climate extremes they suffered and the construction and abandonment of their settlements. In fact, under a microscope, experts can determine in exactly what year a barbed wire fence made a wound into a tree, helping to settle modern property disputes.
Tree rings may also help solve some of history's mysteries. For example, Stahle believes drought may have played a part in the New World's "Lost Colony" of Roanoke. "This is the drought of 1587, '88, and '89. That was the most severe drought of 800 years in this part of the United States, and 1587 was a particularly significant year because Virginia Dare, the first English baby born in the New World, and the other colonists at the Roanoke colony in North Carolina, were last seen in the summer of 1587," says Stahle, pointing to some extremely skinny rings on a piece of bald cypress from Blackwater River, Virginia.
So what trees do these experts like to study most?
"In the pantheon of tree species for dendrochronology, there are a few that are the crème de la crème, if you will--the very best species in the world. There are a limited number of them and really, in North America, it would be the Douglas fir, especially grown on arid sites in the interior of the continent," says Stahle.
Also among his favorites: ponderosa pine, the southern bald cypress in the United States, and the Montezuma bald cypress in Mexico.
His work also involves the bigger picture of protecting the world's forests. "These forests are being cleared and cut even today because progress marches on. So it's kind of a burden on the dendrochronological community to try to identify these relic old-growth forests that are still found and still threatened in many parts of our country," notes Stahle. "But, it's a great pleasure to travel to remote areas in the United States or Mexico to original forests, even virgin forests, with old growth trees, and there are precious few of these locations left. I think they're aesthetically beautiful; these old growth forests are important from an ecological perspective, and for the climate histories they preserve in their annual rings."

"Epidemiological" Study Demonstrates Climate Change Effects on Forests

An 18-year study of 27,000 individual trees by National Science Foundation (NSF)-funded scientists finds that tree growth and fecundity--the ability to produce viable seeds--are more sensitive to climate change than previously thought.
The results, published tomorrow in the journal Global Change Biology, identify earlier spring warming as one of several factors that affect tree reproduction and growth. 
They also show summer drought as an important but overlooked risk factor for tree survival, and that species in four types of trees--pine, elm, beech, and magnolia--are especially vulnerable to climate change.
The findings may help scientists and policymakers better predict which species are vulnerable to climate change and why.
"In a sense, what we've done is an epidemiological study on trees to better understand how and why certain species, or demographics, are sensitive to variation and in what ways," says James Clark of Duke University, lead author of the paper.
To conduct the study, Clark and colleagues measured and recorded the growth, mortality and fecundity of each of the 27,000 trees at least once every three years, ultimately compiling an archive of more than 280,000 tree-years of data.
Using a specially designed bioinformatic analysis, they quantified the effects of climate change on tree species over time.
"This work demonstrates the limitations of current modeling approaches to predict which species are vulnerable to climate change and illustrates the importance of incorporating ecological factors such as species competition," says Alan Tessier, program director in NSF's Division of Environmental Biology, which funded the research.
The approach allowed the scientists to calculate the relative importance of various factors, alone and in combination, including the effects of localized variables such as competition with other trees for light, or the impact of summer drought.
"As climate continues to change, we know forests will respond," says Clark.
"The problem is, the models scientists have used to predict forest responses focus almost solely on spatial variation in tree species abundance--their distribution and density over geographic range."
If all trees of a species grew in the same conditions--the same light, moisture, soil and competition for resources--this generalized, species-wide spatial analysis might suffice, Clark says.
Then scientists wouldn't need to worry about demographic variables and risk factors when trying to predict biodiversity losses due to climate change.
"But in the real world, we do," Clark says. "That's where the new concept of climate and resource tracking of demographic rates comes in.
"Trees are much more sensitive to climate variation than can be interpreted from regional climate averages."
The trees studied included 40 species, located in eleven different forest stands in three geographic regions of the Southeast--the southern Appalachians, the Piedmont and the coastal plain.
They were subjected to both natural and experimental variations.
"By quantifying the effects and relative importance of competition [between species] and climate variables," says Clark, "including impacts on fecundity, over both time and space, the model we've developed addresses this need and can be used to guide planning."