NSF: Earth Week: In a drought, which trees risk death? .- Semana de la Tierra: En una sequía, que la muerte árboles es un riesgo?

Hola amigos: A VUELO DE UN QUINDE EL BLOG., La sequía dejó 225 millones de árboles muertos en el suroeste de EE.UU. en 2002. Nueve años más tarde, que mató a 300 millones de árboles en Texas. El año pasado, 12 millones de árboles murieron en California.
En todo el mundo, un gran número de árboles se están muriendo en el calor extremo y la sequía. Tales matanzas colectivas pueden tener consecuencias importantes para el futuro de los bosques y el clima de la Tierra. En la Semana de la Tierra, los científicos están tratando de entender cómo el calentamiento global podría afectar la frecuencia ocurren los eventos de mortalidad de árboles - y qué tan grave que podría llegar a ser.
Una Universidad de Utah,un biólogo puede ser capaz de ayudar. William Anderegg y sus colegas buscaron patrones en los estudios previos de mortalidad de los árboles y encontraron algunos rasgos comunes que caracterizan las que vivía especies y que murió durante la sequía. Los resultados, publicados hoy en la revista Proceedings de la Academia Nacional de Ciencias (PNAS), pueden ayudar a trazar el futuro de los bosques.

More information.............

http://www.nsf.gov/news/news_summ.jsp?cntn_id=138226&WT.mc_id=USNSF_51&WT.mc_ev=click

Study identifies tree traits that contribute to drought vulnerability

Ponderosa pine on Grand Canyon rim falling over from a drought attack. Credit and Larger Version

April 18, 2016

Drought left 225 million trees dead in the U.S. Southwest in 2002. Nine years later, it killed 300 million trees in Texas. This past year, 12 million trees died in California.

Throughout the world, large numbers of trees are dying in extreme heat and drought. Such mass die-offs can have critical consequences for the future of forests and Earth's climate. On Earth Week, scientists are trying to understand how a warming climate could affect how often tree mortality events occur -- and how severe they could become.

A University of Utah biologist may be able to help. William Anderegg and his colleagues looked for patterns in previous studies of tree mortality and found some common traits that characterized which species lived and which died during drought. The results, published today in the journal Proceedings of the National Academy of Sciences (PNAS), can help chart the future of forests.

"There are some common threads that we might be able to use to predict which species are going to be more vulnerable in the future," Anderegg says.

 

Forests in crisis

 

"With drought projected to increase, predicting tree death is imperative to understanding changes in Earth's forests," says Liz Blood, program director in the National Science Foundation (NSF) Division of Environmental Biology, which funded the research. "This study offers important new insights into how and why trees die from drought, and which trees are at greatest risk."

Worldwide, forests absorb the equivalent of about one-quarter of the carbon dioxide emissions humans produce. So large-scale tree die-offs not only shut down a forest's ability to sequester greenhouse gases but also release some of those gases back into the atmosphere as dead trees decompose.

In climate models, scientists have had difficulty accounting for these changes in carbon dioxide storage. The effect of drought on various species' mortality rates has been difficult to predict. "That launched this search to understand what about a tree's physiology predisposes it to die during a severe drought," Anderegg says.

The researchers combed through 33 published studies of tree mortality that included 475 tree species and more than 760,000 individual trees. The team noted mortality rates for each species, then compared those to 10 tree physiological traits, searching for commonalities.

The traits included typical tree characteristics such as wood density, rooting depth and basic leaf characteristics, and whether the species was evergreen or deciduous. Other traits concerned the hydraulics of how water moves through trees.

 

Tree 'heart attack'

 

The researchers found only three traits that significantly predicted tree drought mortality, all of which related to hydraulics.

Roots take in water, which is pumped throughout the tree to hydrate leaves and support photosynthesis. In times of plenty, water moves easily through the tree. But when temperatures increase, evaporation from leaves drives higher water demand.

At the same time, if drought makes water harder to come by, the tree's roots have to pull harder to draw scant moisture from the soil. Tension builds in the tree's "pipes" as they work harder and harder to move water, like a person trying to suck a thick smoothie through a small straw.

At a certain point, tension on the "pipes" becomes so great that bubbles of air enter them and block water flow. The result is called an embolism.

"It's a little bit akin to a tree heart attack," Anderegg says. "You can actually hear this on a hot summer day if you stick a microphone up to a tree -- you can hear little pings and pops as these pipes get filled with air." Blocked pipes lead to tree death.

The three traits Anderegg found that significantly affected tree mortality were:

• The point at which a tree loses 50 percent of its hydraulic conductivity due to embolism.
• The point at which a tree loses 88 percent of total hydraulic conductivity.
• The hydraulic safety margin, the range between the tension of water the tree allows during dry conditions and the tension that causes hydraulic dysfunction.

Other traits did not affect tree mortality nearly as much as these characteristics. Anderegg says trees accustomed to plentiful water, such as trembling aspens, are more susceptible than junipers, which are better adapted to dry conditions.

 

Signs of climate change

 

The next step is to incorporate these traits into climate models and forest models to help public and private land managers forecast which trees might be most susceptible to drought.

Anderegg says that recent tree-killing droughts in the western U.S. were marked more by elevated temperature -- a sign of a warming world -- than by a lack of rainfall.

"These widespread tree die-offs are a really early and visible sign of climate change already affecting our landscapes," he says.

-NSF-

Media Contacts Cheryl Dybas, NSF, (703) 292-7734, cdybas@nsf.gov
Paul Gabrielsen, University of Utah, (801) 585-6861, paul.gabrielsen@utah.edu

Related WebsitesNSF Grant: Extreme Events and Ecological Acclimation: Scaling from Cells to Ecosystems: http://www.nsf.gov/awardsearch/showAward?AWD_ID=1340270&HistoricalAwards=false

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2016, its budget is $7.5 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 48,000 competitive proposals for funding and makes about 12,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.

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Useful NSF Web Sites:
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Dead oak trees line a forest near Mancos, Colorado.
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These trembling aspen trees near Fairplay, Colorado, were killed by severe drought.
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Drought stress felled these trembling aspens near Flagstaff, Arizona.
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Dead trees from recent droughts in the San Juan National Forest near Mancos, Colorado.
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Drought near Grand Junction, Colorado, resulted in the deaths of many trembling aspens.
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The National Science Foundation (NSF)
Guillermo Gonzalo Sánchez Achutegui
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nsf.gov - National Science Foundation - Harvesting sunlight to help feed and fuel the world

Three U.S./U.K. funded projects have been awarded a total of almost $9 million in additional funding to continue research projects aimed at improving the efficiency of photosynthesis

Scientists are using novel methods to explore potential new ways to boost photosynthetic efficiency. Credit and Larger Version

May 30, 2014

Three research teams--each comprised of scientists from the United States and the United Kingdom--have been awarded a second round of funding to continue research on news ways to improve the efficiency of photosynthesis.

 

Societal benefits

The ultimate goal of this potentially high-impact research is to develop methods to increase yields of important crops that are harvested for food and sustainable biofuels. But if this research is successful, it may also be used to support reforestation efforts and efforts to increase the productivity of trees for the manufacture of wood and paper and thousands of other products that are derived from wood and chemicals extracted from trees. Another reason why photosynthesis is an important research topic: It has made the Earth hospitable for life by generating food and oxygen.

The second round of funding to the three refunded research teams is from the U.S.'s National Science Foundation (NSF) and the U.K.'s Biotechnology and Biological Sciences Research Council (BBSRC). This funding will total almost $9 million over three years. Each team is receiving additional funding because of the significant progress it achieved via its initial round of funding, which was also jointly awarded by NSF and the BBSRC in 2011.

 

Why and how can the efficiency of photosynthesis be increased?

A photosynthesizing organism uses sunlight and carbon dioxide to produce sugars that fuel the organism and release oxygen. But photosynthesis is a relatively inefficient process, usually capturing only about 5 percent of available energy, depending on how efficiency is measured. Nevertheless, some species of plants, algae and bacteria have evolved efficiency-boosting mechanisms that reduce energy losses or enhance carbon dioxide delivery to cells during photosynthesis.

Each of the three funded research teams is working, in a new and unique way, to improve, combine or engineer these types of efficiency-boosting mechanisms, so they may eventually be conferred on important crops that provide food or sustainable biofuels.

Scientists have long sought ways to increase the efficiency of photosynthesis but without, thus far, producing significant breakthroughs. The potentially transformational methods currently being pursued by the three funded teams were developed during an "Ideas Lab"--a workshop held in 2010 that was specially designed to generate innovative, potentially transformative research projects that might open longstanding bottlenecks to photosynthesis research.

If successful in helping to open such bottlenecks and generate ways to improve photosynthetic efficiency, any of the three re-funded research projects could provide critical support for efforts to address food and fuel challenges currently created by increasing human populations and other factors.

John Wingfield, NSF's assistant director for the Directorate of Biological Sciences, said, "Photosynthesis captures abundant and free solar energy and generates food and oxygen for the planet. Emerging technologies, like synthetic biology, are used in these potentially transformative projects to address the long-standing quest to increase efficiency of photosynthesis."

 

The three refunded projects:

1. Plug-and-play photosynthesis led by Anne Jones of Arizona State University: Some single-celled microbes capture solar energy and convert it to fuel for self-replication. Plug-and-play photosynthesis aims to distribute the capture and conversion of energy to two environments, so that each environment can be optimized for maximum efficiency for its role.

The plug-and-play team's overall goal is to capture unused energy, which would otherwise be dissipated, from a light-capturing photosynthetic cell--and transfer it to a second cell for fuel production. One way to carry out this energy transfer is to repurpose bacterial nanowires, which are tiny, electrically conductive wires that are present in some bacteria for reasons that are not yet completely understood.

These wires will be bioengineered to form an electrical bridge between light-capturing cells and fuel-producing cells--so that the wires will conduct energy from the former to the latter. To advance this project the plug-and-play team, together with other investigators, have corrected a false, but long accepted, mischaracterization of the biochemical composition of the bacterial nanowires and have thereby provided a new starting point for further study and engineering.

The research team is also working to develop another approach to intercellular energy transfer by creating new chemical pathways that would divert energy from the bacterial light-capturing cell to a designed biofuel-producing cell. The plug-and-play team has advanced this effort by developing a bioelectrochemical device that measures energy production by bacterial light-capturing cells.

 

2. Multi-Level Approaches for Generating Carbon Dioxide (MAGIC) led by John Golbeck of Pennsylvania State University: MAGIC is aimed at engineering a light-driven carbon dioxide pump that will increase the availability of carbon dioxide to an enzyme that promotes photosynthesis and will thereby increase photosynthetic efficiency.

To advance this effort, the team has, through genetic engineering, repurposed a light-sensitive protein, called halorhodopsin, which is found in a one-celled microbe called Natronomonas pharaonis; this protein helps the microbe maintain the correct chemical balance by pumping chloride into it. But the reengineered form of this protein instead pumps carbon dioxide, which is present as bicarbonate, into cells. To evaluate its pump's effectiveness, the team incorporated its light-driven bicarbonate pump into an artificial vesicle. This vesicle contains a dye whose brightness is proportional to carbon dioxide levels in the vesicle's interior--and therefore provides important information about the pump's usefulness. The team is preparing to incorporate its pump into plant cells to determine if resulting increases in the availability of carbon dioxide to plant cells will increase their growth.

 

3. Combining Algal and Plant Photosynthesis (CAPP) led by Martin Jonikas of Stanford University: Chlamydomonas, a unicellular algae, has a pyrenoid--a ball-shaped structure that helps the algae assimilate carbon to improve its photosynthetic efficiency. CAPP is aiming to, for the first time, transplant the algal pyrenoid and its associated components into higher plants--with hopes of improving these plants' photosynthetic efficiency and thus their productivity.

So far, the team has identified novel components of the pyrenoid. It has also made progress towards the development of a protein-based sensor that will be used to compare levels of bicarbonate in several cellular compartments in algae. This sensor will be used to help explain the algae's carbon concentrating mechanism and help evaluate the pyrenoid's effectiveness after it has been transplanted into higher plants.

 

Improving on nature

Jackie Hunter, BBSRC chief executive said, "Nature barely skims the surface when it comes to photosynthesis and making use of the sun's energy. There is huge room for improvement and these research projects are taking steps to help us to unlock hidden potential that could benefit us all. Using the sun's energy more efficiently means a greater potential to produce fuel, food, fibers, useful chemicals and much more."

Gregory Warr, an NSF program director, said, "These projects, if successful, could transform the way we generate the fuel, food, clothing and shelter that plants and microbes provide to us."

-NSF-

Media Contacts Lily Whiteman, National Science Foundation, (703) 292-8310,

lwhitema@nsf.gov
Robert Dawson, U.K. Biotechnology and Biological Sciences Research Council, 01793 413 204, Robert.Dawson@bbsrc.ac.uk

Program Contacts Gregory Warr, National Science Foundation, (703) 292-8284,

 gwarr@nsf.gov
Kent Dearn Chapman, National Science Foundation, (703) 292-7879,

 kchapman@nsf.gov

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

 Get News Updates by Email 

Useful NSF Web Sites:
NSF Home Page:

 http://www.nsf.gov
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For the News Media:

 http://www.nsf.gov/news/newsroom.jsp
Science and Engineering Statistics:

 http://www.nsf.gov/statistics/
Awards Searches:

 http://www.nsf.gov/awardsearch/

Plug-and-play will separate processes into two environments connected by conductive nanowires.
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The MAGIC team's pump will transport into cells bicarbonate (HCO3-) that will be converted into CO2.
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CAPP: An algea pyrenoid appears blue and its chloroplast, a photosynthesizing unit, appears green.
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The National Science Foundation (NSF)
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nsf.gov - California's iconic redwoods in ganger from fire and infectious disease

Pathogen that causes sudden oak death leaves redwoods vulnerable to fire.-

Iconic coastal redwood forests are threatened by a link between disease and wildfire. Credit and Larger Version

August 21, 2013

The following is part six in a series on the NSF-NIH Ecology and Evolution of Infectious Diseases (EEID) Program. For part one, see Cool Cat in a Hot Zone. For part two: Snails in the Waters, Disease in the Villages. For part three: Underwater Whodunit: What's Killing Florida's Elkhorn Coral? For part four: "Defective" Virus Leads to Epidemic of Dengue Fever. For part five: Sick Sea Fans: Undersea "Doctors" to the Rescue.

First it was sudden oak death, the oak disease caused by the plant pathogen Phytophthora ramorum, that threatened California's extensive coastal forests.

Now these forests' stately trees are facing a new menace: the combined effects of sudden oak death and fire. And this time, the iconic redwoods are at risk.

Usually resistant to the effects of wildfires, California's coast redwoods are now burning as fast as other trees. Why?

 

Into the redwood forest

To find answers, plant pathologist David Rizzo of the University of California at Davis (UC Davis) and colleagues monitored more than 80,000 hectares of forests near Big Sur, Calif. In their plots, tanoaks, California bay laurels and coast redwoods grow.

The study began in 2006. "In 2008, almost half our plots were burned by wildfires that lasted the better part of a month," says Rizzo.

That was the beginning of the end for many coast redwoods, surprising researchers who expected the trees to be fire-proof.

The key to the redwood deaths, discovered Rizzo, Margaret Metz and Kerri Frangioso of UC Davis, along with Morgan Varner of Mississippi State University and Ross Meentemeyer of North Carolina State University, lies in the sudden oak death pathogen.

"If redwoods didn't live in forests affected by the disease," says Metz, "they could withstand fires just fine."

The biologists recently reported their results online in the journal Ecology, published by the Ecological Society of America.

After the fires were under control, the scientists returned to their study plots. Half had long been infested with the sudden oak death pathogen; half had been spared. The redwoods' mortality risk, it turned out, was four times higher in the sudden oak death plots as in healthy plots.

"The disease likely created more fuel for wildfires as dead tanoak branches fell," says Rizzo. "The loss of the oaks also would have decreased the amount of shade, drying out the forest and turning it into a tinder box, one not even redwoods could survive."

 

Pathogens + fires = dead redwoods

The forest ecosystem disturbance that happens when a pathogen like sudden oak death becomes established and starts killing trees, says Rizzo, "clearly isn't the only one that may be important to that forest."

Sudden oak death has killed millions of trees in the coastal forests of California and Oregon. It was first linked with the mortality of tanoaks and coast live oaks in the San Francisco Bay area in the mid-1990s. In 2000, Phytophthora ramorum was confirmed as the causal agent.

Analyses of the pathogen's genetic structure indicate that a single introduction sparked the wave of disease. It likely originated at a nursery in Santa Cruz, Calif.

Since then, scientists have found that the pathogen has infected plants in 45 genera, including ferns. "These host species are important parts of the forests along the California coast and at the wildland-urban interface," says Rizzo.

The pathogen's current range extends more than 435 miles from the Big Sur area in central California north to Mendocino County, with smaller affected areas in Humboldt County, Calif., and Curry County, Ore. Forests along Big Sur are among the most affected, with 100 percent of tanoaks infected in some stands.

Many of those forests are also prone to wildfires. "There's a growing concern that dead trees from the disease may make wildfires worse," Metz says.

The 2008 wildfires were the first in forests affected by sudden oak death. The largest fire, called the Basin Complex, was ignited by a lightning storm in June. It burned more than 95,000 hectares in the Big Sur region.

In September, the Chalk Fire started south of the Basin Complex perimeter; it burned an additional 16,000 acres. "More than 40 percent of our 280 plots went up in flames, 98 in the Basin Fire, and 23 in the Chalk Fire," says Rizzo.

A month after containment of the Basin Complex fire, the researchers surveyed 61 plots to measure burn severity before the forest could change with the onset of California's winter rains. "These measurements serve as our baseline data on ecosystem responses to interactions between fire and infectious disease," says Rizzo.

Key hidden high in the forest canopy

When sudden oak death kills tanoaks, it alters the trees in ways that leave neighboring redwoods vulnerable, the researchers found.

Flames are carried high into the tree canopy by the dead tanoaks; they then scorch the crowns of surrounding redwoods. Injury to the redwoods' crowns is what likely caused the trees to die in the 2008 fires, the scientists believe.

"Humans are causing widespread changes throughout our world, including greater wildfires related to changing climate and from increasing infectious diseases due to more modes of transportation," says Sam Scheiner, program director at the National Science Foundation (NSF) for the joint NSF-NIH Ecology and Evolution of Infectious Diseases Program, which funded the research.

"This study shows that these changes can combine in unexpected ways that can be very destructive. More such research is needed if we are to prepare for what's to come."

Rizzo agrees. "We're moving species around the globe at high rates, and global warming has increased fire severity. There may be all sorts of consequences, among them, dead and dying coast redwoods."

--	Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov

Investigators David Rizzo

Related Institutions/Organizations University of California-Davis

Related Awards#1115664 Collaborative Research: Interacting disturbances: leaf to landscape dynamics of emerging disease, fire and drought in California coastal forests

Total Grants $558,126

Related WebsitesNSF News: History is Key Factor in Plant Disease Virulence:

 http://www.nsf.gov/news/news_summ.jsp?cntn_id=123869
NSF Special Report: Ecology and Evolution of Infectious Diseases:

 http://www.nsf.gov/news/special_reports/ecoinf/index.jsp
NSF News: Investigating the Spread of Infectious Diseases With NSF, NIH, U.K. Funding:

 http://www.nsf.gov/news/news_summ.jsp?cntn_id=121607
NSF News: Controlling the Spread of Diseases Among Humans, Other Animals and the Environment:

http://www.nsf.gov/news/news_summ.jsp?cntn_id=125496
NSF News: Interplay of Ecology, Infectious Disease, Wildlife and Human Health Featured at Annual Conference:

http://www.nsf.gov/news/news_summ.jsp?cntn_id=128411

Fire consumes a once-healthy California redwood tree.
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Dead tanoaks in a redwood forest in the scientists' California study area, pre-fire.
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Researchers conduct a post-fire survey two months after a 2008 blaze.
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Scorched redwoods soon after the Basin Fire in Big Sur, Calif.
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Two years after the fire, the ecologists returned to survey the burned redwood forests.
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Guillermo Gonzalo Sánchez Achutegui
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ayabaca@hotmail.com
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nsf.gov : Ghosts of Forests Past: Bark Beetles Kill Lodgepole Pines, Affecting Entire Watersheds

Bark beetle epidemic changing water quality as well as forest health,

Ghosts of a forest past: bark beetle-killed trees overlook Grand Lake, Colo. Credit: Lindsay Bearup

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Bark beetle-felled trees fall, landing on a river and likely affecting the health of its waters. Credit: Lindsay Bearup

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Scientists take soil and microbial samples beneath a beetle-killed tree. Credit: Thomas Cooper, Lightbox Images

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Beetle-killed trees line a river; researchers have found water quality changes. Credit: Lindsay Bearup

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Beetles burrowing into pines create open areas in the trees' bark. Credit: Lindsay Bearup

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Researchers conduct experiments on the influence of chemicals in pine needles on soil. Credit: Thomas Cooper, Lightbox Images

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The following is part eleven in a series on the National Science Foundation's Science, Engineering and Education for Sustainability (SEES) investment. Visit parts one, two, three, four, five, six, seven, eight, nine and ten in this series.

In mountains across the Western United States, scientists are racing against time--against a tiny beetle--to save the last lodgepole pines.

Forests are bleeding out from the effects of the beetles, their conifers' needles turning crimson before the trees die.

Now, researchers are also hurrying to preserve the region's water quality, affected by the deaths of the pines.

"When these trees die," says hydrologist Reed Maxwell of the Colorado School of Mines, "the loss of the forest canopy affects hydrology and the cycling of essential nutrients."

Maxwell and other scientists recently published results of their study in the journal Biogeochemistry.

Co-authors, in addition to Maxwell, are Kristin Mikkelson, Lindsay Bearup, John McCray and Jonathan Sharp of the Colorado School of Mines, and John Stednick of Colorado State University. Mikkelson is the paper's first author.

Bark beetle numbers: heating up

"The mountain pine beetle outbreak in Western states has reached epidemic proportions," says Maxwell.

Bark beetles, as they're known, are native to the United States. They're so-named as the beetles reproduce in the inner bark of trees. Some species, such as the mountain pine beetle, attack and kill live trees. Others live in dead, weakened or dying hosts.

Massive outbreaks of mountain pine beetles in western North America since the mid-2000s have felled millions of acres of forests from New Mexico to British Columbia, threatening increases in mudslides and wildfires.

Climate change could be to blame. The beetles' numbers were once kept in check by cold winter temperatures and trees that had plenty of water to use as a defense.

But winters have become warmer, and droughts have left trees water-stressed and less able to withstand an onslaught of winged invaders.

"A small change in temperature leads to a large change in the number of beetles--and now to a large change in water quality," says Tom Torgersen, director of the National Science Foundation's (NSF) Water, Sustainability and Climate (WSC) Program, which funded the research.

WSC is part of NSF's Science, Engineering and Education portfolio of investments.

"Bark beetles have killed 95 percent of mature lodgepole pines," says Maxwell.

Death of a lodgepole pine

But the trees don't die immediately.

When beetles invade, a blue fungus spreads inside a tree's trunk, choking off transpiration and killing the tree in about two years.

The trees turn blood-red, then the ashen gray of death, dropping their needles to the forest floor.

"Some of the most important effects of bark beetles may be changes in the hydrologic cycle," says Maxwell, "via snow accumulation under trees and water transpiration from trees and other plants."

Biogeochemical changes may be even more important, he says, with carbon and nitrogen cycles interrupted.

"We're studying these hydrologic and geochemical processes through a combination of field work, lab research and computer modeling," says Maxwell.

Whither the beetles, so the trees, forests...and waters

Changes in tree canopies affect snowpack development and snowmelt.

For example, a lack of needles on branches lets more snow fall through the canopy--snow that would otherwise be caught on branches. A tree without needles also has less shade beneath it.

The result is a shallower snowpack, earlier snowmelt and less water in spring.

"The real question," Maxwell says, "is how these processes translate from individual trees to hillslopes to large watersheds."

Dead trees don't transpire water. Once a forest has died, this important flow of moisture from the ground to the atmosphere ceases.

That can mean a loss of as much as 60 percent of the water budget, although increases in ground evaporation or transpiration from understory shrubs and bushes may compensate for some of the lack.

"Combined with what's happening to snowpack depth," says Maxwell, "it becomes a complicated relationship that can change the timing and magnitude of spring runoff from snowmelt--and an entire year's water resources."

Tree mortality also appears to affect forest carbon and nitrogen cycles through increases in dissolved organic carbon.

"We've seen changes in drinking water quality in beetle-affected watersheds that are almost certainly related to high dissolved organic carbon levels," says Maxwell.

As Maxwell, Mikkelson, Bearup and colleagues discovered, there's a lag time between beetle infestation and water quality declines, "so tree and forest water transport processes are very likely involved," says Maxwell.

All watersheds great and small

The observations prompted the researchers to study processes at the individual tree and hillslope scale to better understand what's happening in watersheds large and small.

"Watersheds are complex, interrelated systems," says Maxwell, "which makes understanding them more challenging.

"We're developing complex, numerical models of bark beetle-infested watersheds that include our best understanding of how and where water flows. The models are allowing us to isolate individual processes by turning them on and off in 'what-if' scenarios."

Along with on-the-ground observations, he says, "they're showing us more of the complex story of pine beetle effects on Western watersheds.

"We now know that healthy watersheds ultimately depend on healthy forests."

Western streams and rivers soon may be part of dead and dying forests, surrounded only by the ghosts of lodgepole pines past.

Related WebsitesNSF Science, Engineering and Education for Sustainability (SEES) Programs:

 http://www.nsf.gov/sees
NSF "Discoveries in Sustainability" Publication:

 http://www.nsf.gov/pubs/2012/disco12001/disco12001.pdf
NSF News Release: How Is Earth's Water System Linked With Land Use, Climate Change and Ecosystems?:  

http://www.nsf.gov/news/news_summ.jsp?cntn_id=125434&org=NSF&from=news

NASA

Guillermo Gonzalo Sánchez Achutegui

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ayabaca@hotmail.com

ayabaca@yahoo.com

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nsf.gov - News - Scientists Undertake Extensive Field Campaign to Study U.S. Southeast Atmospheric Chemistry

Research examines chemical reactions between human-related pollution and volatile organic compounds (VOCs) emitted by vegetation such as trees.-

Southeast Atmosphere Study (SAS) tower in the Talladega National Forest in Alabama. Credit: Southeast Atmosphere Study

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Top-of-tree-canopy view of the SAS instrument tower in the Alabama forest. Credit: Southeast Atmosphere Study

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Close-up of the instrument tower being used by SAS atmospheric chemists. Credit: Southeast Atmosphere Study

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SAS scientists are conducting research aboard the NSF/NCAR C-130 aircraft. Credit: NSF/NCAR

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Scientists get ready to fly across the U.S. Southeast in search of air quality discoveries.
Credit: Southeast Atmosphere Study/NOAA
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Researchers prepare to sample air chemistry from the skies rather than the ground.
Credit: Southeast Atmosphere Study/NOAA
Download the high-resolution JPG version of the image. (42 KB)

In the largest U.S. atmospheric chemistry field project in decades, researchers sponsored by the National Science Foundation (NSF) and other organizations are working to study tiny particles and gases in the air over the southeastern United States.

The study looks at the chemical reactions between human-related pollution and volatile organic compounds (VOCs) emitted by vegetation such as trees in forests.

The project, called the Southeast Atmosphere Study, or SAS, runs through July 15, 2013. It's part of an unprecedented campaign, say the scientists, to investigate the relationship between air chemistry and climate change.

SAS is supported by NSF, the U.S. Environmental Protection Agency and the U.S. National Oceanic and Atmospheric Administration, along with the Electric Power Research Institute. Participants are from some 30 U.S. and international research institutions.

Atmospheric chemists have long known that human-made pollutants have the potential to interact with plant-emitted VOCs, turning them into airborne particles, or aerosols, that may then affect air quality and human health.

In the Southeast, the aerosols also affect the region's climate. The southeastern United States is one of the few places on Earth displaying an overall cooling trend over the last century.

"The Southeast Atmosphere Study will illuminate the role of the surface biosphere in producing volatile organic gases that can then form new particles, known as secondary organic aerosols (SOAs)," says Michael Morgan, NSF division director for Atmospheric and Geospace Sciences.

"The formation of SOAs has been observed over many forested regions of the world. Emission of these gases may have an important influence on our changing climate."

Some scientists believe that enhanced SOA formation may be responsible for an "aerosol cooling effect" that would explain the divergence of southeastern U.S. temperature trends from global average temperature trends over the last century.

Black aerosols produced by industry, home heating and other means absorb incoming solar radiation, increasing global temperatures, say scientists such as Ann Marie Carlton of Rutgers University in New Brunswick, N.J., lead NSF-funded SAS investigator.

However, many lighter-colored aerosols, such as those composed of sulfates or organics from vegetation typical of the Southeast, have a cooling effect because they reflect some amount of incoming light back to space, says Alex Guenther of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., also a scientist on the project.

Some of these aerosols get carried high into the atmosphere, affecting temperatures over a large area. But many linger in the region where they were emitted, resulting in more localized effects.

High concentrations of light-colored aerosols such as those expected in the Southeast can reduce the average temperature in the region, offsetting the warming caused by greenhouse gases circulating around the globe.

But those same aerosols can trigger chemical reactions that worsen air pollution such as ground-level ozone.

Certain types of aerosols affect cloud formation and cloud opacity; both can affect the amount of energy trapped in Earth's atmosphere.

Computer simulations can replicate some of the influences of aerosols. But they can't yet produce the level of detail required for a complete understanding of these complex chemical and atmospheric dynamics, which would lead to more accurate predictions of future air quality and regional climate.

To address these questions and improve observations that may be used to expand the capabilities of climate and chemistry models, SAS investigators are bringing a suite of air sampling equipment and sensors to the Southeast.

Project scientists are using two aircraft, the NSF/NCAR C-130 and the NOAA P-3, to sample air chemistry from the Mississippi River to the Atlantic Ocean, and from the Ohio River Valley to the Gulf of Mexico.

Researchers are also using ground instruments to measure low-level winds, moisture, temperature and chemistry.

Instrumented towers reaching some 150 feet high are taking measurements within and above forest canopies.

Additional aircraft and ground sensors deployed by companion programs will help paint an accurate atmospheric chemistry picture of this unique region.

NSF Southeast Atmosphere Study (SAS) Principal Investigators

Ann Marie Carlton, Rutgers University, New Brunswick:
Collaborative Research: Atmospheric mixed phase chemistry for improved climate predictions: field measurements and modeling of the Southern Oxidant and Aerosol Study

William Brune, Pennsylvania State Univ., University Park:
Resolving issues of OH measurements and oxidation chemistry in forest environments

Rodney Weber, Georgia Tech Research Corporation:
Collaborative Research: Atmospheric mixed phase chemistry for improved climate predictions: field measurements and modeling of the Southern Oxidant and Aerosol Study

Donald Collins, Texas A&M University Main Campus:
Collaborative Research: Sensitivity of gas and aqueous phase production of secondary organic aerosol to chemical and environmental perturbations

Robert Griffin, William Marsh Rice University:
Collaborative Research: Sensitivity of gas and aqueous phase production of secondary organic aerosol to chemical and environmental perturbations

Delphine Farmer, Colorado State University:
Organic acid concentrations and fluxes over a Southeastern forest during the Southern Oxidant and Aerosol Study

Allen Goldstein, University of California-Berkeley:
Contribution of Biogenic Volatile Organic Compounds to Organic Aerosol Formation in the Presence and Absence of Anthropogenic Pollution

Jose Jimenez, University of Colorado at Boulder:
Collaborative Research: Investigation of the Effects of Anthropogenic-Biogenic Interactions on Secondary Organic Aerosol Formation

Douglas Worsnop, Aerodyne Research, Inc.:
Collaborative Research: Investigation of the Effects of Anthropogenic-Biogenic Interactions on Secondary Organic Aerosol Formation

Frank Keutsch, University of Wisconsin-Madison:
Field and laboratory study of rural VOC oxidation and SOA formation utilizing measurements of formaldehyde and glyoxal

Jesse Kroll, Massachusetts Institute of Technology:
Measurement of Low-Volatility Gas-Phase Organic Compounds during the Southern Oxidant and Aerosol Study

Shan-Hu Lee, Kent State University:
Measurements of Amines During the SOAS (SAS) Field Campaign

Paul Wennberg, California Institute of Technology:
Hydroperoxide, Nitrate, and Epoxide Chemistry of Biogenically produced Alkenes

Xianliang Zhou, Health Research Inc/New York State Health Department:
Collaborative Research: Photolysis of Particulate Nitrate as a Daytime HONO Source and a Re-NOx-ification Pathway in the Troposphere

Jochen Stutz, University of California-Los Angeles:
Collaborative Research: Photolysis of Particulate Nitrate as a Daytime HONO Source and a Re-NOx-ification Pathway in the Troposphere

Daniel Jaffe, University of Washington:
Collaborative Research: The North American Airborne Mercury Experiment

Noelle Selin, Massachusetts Institute of Technology:
Collaborative Research: The North American Airborne Mercury Experiment

Christopher Cantrell, University of Colorado at Boulder:
Collaborative Research: The North American Airborne Mercury Experiment

-NSF-

Media Contacts Cheryl Dybas, NSF (703) 292-7734

 cdybas@nsf.gov
David Hosansky, NCAR (303) 497-8611

 hosansky@ucar.edu

Related WebsitesSoutheast Atmosphere Study: 

http://www.eol.ucar.edu/projects/sas/

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget was $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

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