Building a Better Weather Forecast? SMAP May Help

SMAP's soil moisture measurements will help with forecasts of precipitation and temperature. Image credit: UCAR

If you were trying to forecast tomorrow's weather, you would probably look up at the sky rather than down at the ground. But if you live in the U.S. Midwest or someplace with a similar climate, one key to a better weather forecast may lie beneath your feet.

Precipitation and temperature are part of every weather forecast. Precipitation comes from clouds, clouds are formed of airborne water vapor, and vapor comes from evaporating soil moisture -- so soil moisture governs precipitation. Evaporating soil moisture also makes air cooler, so it affects temperature. In certain kinds of climate, scientists believe, soil moisture is so influential that better observations of it might improve weather forecasts. These climates are transitional: not too humid and not too dry. For example, the agriculturally productive states of the U.S. Midwest fall into that category.

"Better soil moisture observations lead to better land-atmosphere interaction in weather forecasting models and ultimately to a better prediction of temperature and precipitation," said Michael Ek, leader of the Land Hydrology Team at the Environmental Monitoring Center of the National Oceanic and Atmospheric Administration (NOAA). "Weather models need good initial observations of the land surface, or you're starting from the wrong place."

Better soil moisture observations are just what the Soil Moisture Active Passive (SMAP) mission will provide. Scheduled for launch on Jan. 29, SMAP will collect the most accurate and highest-resolution soil moisture measurements ever made from a satellite SMAP will cover the entire globe in two to three days. Ek is a member of one of five groups in SMAP's Early Adopter program that have been working for several years on the question of how best to incorporate the new data into national weather forecasting models.

Forecasts will not improve, however, the moment SMAP starts collecting data. U.S. Department of Agriculture research scientist Wade Crow, a member of SMAP's science team, explained that, since closely spaced global soil moisture measurements have never existed before, the mathematical models used in weather forecasting are not configured to include them directly. Getting the best use out of the new observations has been a subject of active research for several years and will require some significant changes in how soil moisture data are assimilated into the models.

Data assimilation is necessary because weather forecasting models all drift a bit, like cars. If you're driving on a perfectly straight road, you still need to keep a hand on the steering wheel or you'll run off the edge sooner or later. Data assimilation in a model serves the same purpose as the slight movements of your hands that keep your car on course.

Drift is not a fatal flaw for a weather forecasting model any more than it is for a car. It is simply a sign that the Earth system is too vast and complicated to model perfectly with the resources available today. To steer forecasts toward greater realism, models ingest, or assimilate, real-world data and use them in sophisticated mathematical techniques. Each time updated observations become available, they are assimilated to improve the starting point for the next forecast.

Closely spaced and highly accurate global measurements are an important part of the process. For soil moisture, however, current observations are not on a fine enough scale to meet the needs of weather forecasting models directly. "Modelers compensate for the lack of direct observations of soil moisture by using more indirect measures, such as estimating it from observations of temperature and precipitation," Crow explained. "As a consequence, modeled soil moisture tends to diverge from reality. SMAP will be directly observing the state that they want, so they won't have to back it out from proxy measurements."

JPL scientist Eni Njoku is working with researchers at another forecasting center, the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, England. Njoku said, "SMAP will provide benefits of higher soil moisture accuracy and spatial resolution than have previously been available from satellites. This could lead potentially to improved regional and global weather forecasts by ECMWF." Environment Canada, the branch of the Canadian government responsible for weather forecasting in that nation, is also working on assimilating SMAP data into its models.

"The numerical weather prediction centers are adapting to the new availability of soil moisture information and thinking of ways they can exploit it," Crow summarized. "It will be really exciting to see what they find."

SMAP is managed for NASA's Science Mission Directorate in Washington by the agency's Jet Propulsion Laboratory in Pasadena, California, with instrument hardware and science contributions made by NASA's Goddard Space Flight Center in Greenbelt, Maryland. JPL is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center, at the University of Colorado in Boulder, for public distribution and archiving. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida is responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena.

Source: Nasa

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NASA's SDO sees massive filament erupt on sun

Eruptive events on the sun can be wildly different. Some come just with a solar flare, some with an additional ejection of solar material called a coronal mass ejection (CME), and some with complex moving structures in association with changes in magnetic field lines that loop up into the sun's atmosphere, the corona. Credit: Image courtesy of NASA/Goddard Space Flight Center

Eruptive events on the sun can be wildly different. Some come just with a solar flare, some with an additional ejection of solar material called a coronal mass ejection (CME), and some with complex moving structures in association with changes in magnetic field lines that loop up into the sun's atmosphere, the corona.

On July 19, 2012, an eruption occurred on the sun that produced all three. A moderately powerful solar flare exploded on the sun's lower right limb, sending out light and radiation. Next came a CME, which shot off to the right out into space. And then, the sun treated viewers to one of its dazzling magnetic displays -- a phenomenon known as coronal rain.

Over the course of the next day, hot plasma in the corona cooled and condensed along strong magnetic fields in the region. Magnetic fields, themselves, are invisible, but the charged plasma is forced to move along the lines, showing up brightly in the extreme ultraviolet wavelength of 304 Angstroms, which highlights material at a temperature of about 50,000 Kelvin. This plasma acts as a tracer, helping scientists watch the dance of magnetic fields on the sun, outlining the fields as it slowly falls back to the solar surface.

Source: NASA/Goddard Space Flight Center

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Father-son research team discovers cheatgrass seeds survive wash cycle

Professor Hugh Lefcort and son Caleb examine the cheatgrass in Spokane, Washington. Credit: Gonzaga University

Not many sixth-graders can say they have been published in an academic journal, but Caleb Lefcort can cross that distinction off his list. Caleb got into a discussion with his father, Hugh Lefcort, professor of biology at Gonzaga University, as to whether the seed burrs from cheatgrass would survive the laundry cycle. Hugh believed the seeds would not survive. Instead of simply taking his father's word for it, Caleb -- who was in fourth grade at the time -- suggested the scientific method: an experiment.

The father and son duo set out to determine whether the seeds would survive the wash.
The experiment

Finding cheatgrass seeds was easy. Bromus tectorum (the scientific name for cheatgrass) is nearly ubiquitous in the Inland Northwest and has become an increasing concern throughout North America -- spreading rapidly through the western United States both through natural means and unintended ways, like getting stuck in people's socks and shoes.

"We hypothesized that laundering would impact water potential, and we, therefore, predicted that seeds would exhibit poorer germination and emergence after being laundered," said Hugh. "We also predicted that the effect of laundering would be stronger if bleach was used."

To collect the cheatgrass seeds, Hugh and Caleb walked through a nearby field wearing only socks on their feet. They divided the socks into three different treatments: 1. Not washed or dried; 2. Washed with detergent but not bleach and subsequently dried; and 3. Washed with detergent and bleach and then dried.

The socks that were to be laundered were divided into three different washing machines/detergent/dryer combinations:
1. A Whirlpool washing machine using All brand detergent and Whirlpool dryer;
2. A Samsung washer using Tide brand detergent and a General Electric dryer; and
3. A Maytag machine using Era brand detergent and a Maytag dryer.

Findings

The results of the experiment surprised both Hugh and Caleb.

"There was no significant effect of the different washing machines and their associated laundry detergents and dryers on the number of seeds that sprouted, nor did we find a significant effect of laundry treatments in the number of seeds that germinated," said Hugh.

There was, however, an effect on the seeds that were treated with bleach; they germinated at a slightly slower rate than the other seeds that were tested without bleach. The height of the plants that sprouted from these bleached seeds differed from the height of the plants that experienced the no-bleach-wash treatment.

The research that Hugh and Caleb conducted revealed that cheatgrass seeds and their germination processes are sturdy enough to survive the soaking, soap and agitation of washing machines, the heat of dryers, and often even bleach. Though they designed the study to make it difficult for cheatgrass seeds to germinate, they were surprised at how easily the treated seeds sprouted into plants. Government agencies may consider adding these findings to their public service announcements.

Caleb Lefcort is now a sixth-grader Moran Prairie Elementary School.

Source: Gonzaga University

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'Probiotics' for plants boost detox abilities; untreated plants overdose and die

The Doty lab conducts work to see how plants treated with naturally occurring endophytes might handle soils contaminated with a variety of pollutants. Graduate student Robert Tournay, for example, is interested in how the plants handle arsenic. Credit: M Levin/U of Washington

Scientists using a microbe that occurs naturally in eastern cottonwood trees have boosted the ability of two other plants -- willow and lawn grass -- to withstand the withering effects of the nasty industrial pollutant phenanthrene and take up 25 to 40 percent more of the pollutant than untreated plants.

The approach could avoid the regulatory hurdles imposed on transgenic plants -- plants with genes inserted from or exchanged with other plant or animal species -- that have shown promise in phytoremediation, the process of using plants to remove toxins from contaminated sites, according to Sharon Doty, associate professor of environmental and forestry sciences and corresponding author on a paper about the new work in Environmental Science & Technology.

"Our approach is much like when humans take probiotic pills or eat yogurt with probiotics to supplement the 'good' microbes in their guts," she said.

The microbe from the cottonwood was encouraged to colonize the roots of willows simply by dipping rooted and trimmed cuttings in solutions with the microbe. Grasses were treated with microbes in solution as seeds sprouted in soil. Once integrated into the plants, the microbe supplemented their own microbial defenses.

Microbes that take up residence in the inner tissue of plants and don't cause negative symptoms are called endophytes. In nature, endophytes have a welcomed, symbiotic relationship with plants. In polluted soil, for instance, if the right endophytes are present they consume toxins coming up through plant roots. The endophytes get fed and the plant gets help neutralizing pollutants that could kill it.

That's been one challenge of phytoremediation: plants removing pollutants can, all too quickly, succumb to the toxins.

"When the endophyte in these experiments was given to willow and grasses, it reduced the phytotoxic effects of phenanthrene compared to the control plants that did not receive the endophyte and died," said lead author Zareen Khan, a UW research scientist in environmental and forest sciences.

Phenanthrene is carcinogenic, on the Environmental Protection Agency's priority pollutants list and belongs to a class of polycyclic aromatic hydrocarbons that get deposited into the environment via fossil fuel combustion, waste incineration or as byproducts of industrial processes. Soils that become contaminated can be capped with layers of uncontaminated soil or dug up and removed for cleaning at soil remediation facilities or storage at waste disposal facilities.

In their search, UW researchers tested six different endophytes from cottonwood and willow varieties and found one -- lab name PD1 -- from the eastern cottonwood to be superior at breaking down phenanthrene.

They introduced this endophyte into willow cuttings and lawn grass. Willows were chosen because some varieties have already proven adept at removing toxins and the shrubs have extensive root systems, take up a lot of water and grow rapidly. Lawn grass was included because it also grows fast and could be useful in parks and open-space areas.

In lab experiments, the willow cuttings with added endophyte protection continued to grow, kept their leaves and had denser root systems. Untreated plants wilted, lost leaves and their roots turned brown. When soils were analyzed, the treated willows took up 65 percent of the phenanthrene compared with untreated plants that removed 40 percent, an improvement of 25 percent.

Grass seed planted in contaminated soils and watered with solutions containing the PD1 endophyte germinated five days quicker, grew taller and had 100 more tillers, or new offshoots, after 13 days. Treated grass removed 50 percent of the phenanthrene from the soil, compared with untreated grass that removed 10 percent, an improvement of 40 percent.

In phytoremediation, plants that take up pollutants but don't degrade them have to be removed and treated as hazardous waste or otherwise disposed of safely. The willows treated in the UW experiment appear to have degraded some 90 percent of the phenanthrene to harmless components. The researchers said they'd like to determine if that promising finding holds up in mass-balance studies and want to examine the possible effects on bugs or animals that might bite the plants processing the toxins and other environmental considerations. Interestingly, other studies have shown that bugs can smell similar semi-volatile pollutants and avoid eating the plants containing them, Doty said.

The work was funded by a Small Business Innovation Research grant from the National Institute of Environmental Health Sciences and by funds provided through the Byron and Alice Lockwood Endowed Professorship that Doty holds. The other four co-authors on the paper were undergraduate volunteers: David Roman and Trent Kintz have since graduated while May delas Alas and Raymond Yap are still working on their bachelor's degrees.
Just down the road from UW is Seattle's Gas Works Park, a site Doty thinks is a prime candidate for the approach her lab reported. Contaminants in the soil, including phenanthrene, are from a now-dismantled gasification plant. Soils have been covered with uncontaminated soil.

"The idea of leaving a known carcinogen in a public place is not right," she said. "What about problems of erosion? We should do what we can to remove it. We spend so much money treating cancer, I'd like us to take steps to prevent it instead."

Source: University of Washington

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Ancient wisdom boosts sustainability of biotech cotton

The patchwork of 75 million acres of small farms in northern China includes insecticidal transgenic Bt cotton. Credit: Photo courtesy of Yidong Wu

Advocates of biotech crops and those who favor traditional farming practices such as crop diversity often seem worlds apart, but a new study shows that these two approaches can be compatible. An international team led by Chinese scientists and Bruce Tabashnik at the University of Arizona's College of Agriculture and Life Sciences discovered that the diverse patchwork of crops in northern China slowed adaptation to genetically engineered cotton by a wide-ranging insect pest. The results are published in the advance online edition of Nature Biotechnology.

Genetically engineered cotton, corn and soybean produce proteins from the widespread soil bacterium Bacillus thuringiensis, or Bt, that kill certain insect pests but are harmless to most other creatures including people. These environmentally friendly toxins have been used by organic growers in sprays for decades and by mainstream farmers in engineered Bt crops since 1996. Planted on a cumulative total of more than half a billion hectares worldwide during the past two decades, Bt crops can reduce use of broadly toxic insecticides and increase farmers' profits. However, rapid evolution of resistance to Bt toxins by some pests has reduced the benefits of this approach.

To delay resistance, farmers plant refuges of insect host plants that do not make Bt toxins, which allows survival of insects that are susceptible to the toxins. When refuges near Bt crops produce many susceptible insects, it reduces the chances that two resistant insects will mate and produce resistant offspring. In the United States, Australia and most other countries, farmers were required to plant refuges of non-Bt cotton near the first type of Bt cotton that was commercialized, which produces one Bt toxin named Cry1Ac. Planting such non-Bt cotton refuges is credited with preventing evolution of resistance to Bt cotton by pink bollworm (Pectinophora gossypiella) in Arizona for more than a decade.

Yet in China, the world's number one cotton producer, refuges of non-Bt cotton have not been required. The Chinese approach relies on the previously untested idea that refuges of non-Bt cotton are not needed there because the most damaging pest, the cotton bollworm (Helicoverpa armigera), feeds on many crops other than cotton that do not make Bt toxins, such as corn, soybean and peanuts. The results reported in the new study provide the first strong evidence that these "natural refuges" of non-Bt crops other than cotton delay evolution of pest resistance to Bt cotton.

Tabashnik used computer simulations to project the consequences of different assumptions about the effects of natural refuges in northern China. The simulations mimic the biology of the cotton bollworm and the planting patterns of the 10 million farmers in northern China from 2010 to 2013, where Bt cotton accounts for 98 percent of all cotton, but cotton represents only 10 percent of the area planted with crops eaten by the cotton bollworm.

"Because nearly all of the cotton is Bt cotton, the simulations without natural refuges predicted that resistant insects would increase from one percent of the population in 2010 to more than 98 percent by 2013," said Tabashnik, who heads the UA's Department of Entomology and also is a member of the UA's BIO5 Institute. "Conversely, resistance barely increased under the most optimistic scenario modeled, where each hectare of the 90 percent natural refuge was equivalent to a hectare of non-Bt cotton refuge."

In a third scenario, the researchers used field data on emerging cotton bollworms from different crops to adjust the contribution of each hectare of natural refuge relative to non-Bt cotton. These data were provided by co-author Kongming Wu of the Institute of Plant Protection in Beijing. By this method, the total natural refuge area was equivalent to a 56 percent non-Bt cotton refuge, and 4.9 percent of the insects were predicted to be resistant by 2013.

To distinguish between these possibilities, a team led by co-author Yidong Wu of China's Nanjing Agricultural University tracked resistance from 2010 to 2013 at 17 sites in six provinces of northern China. Insects were collected from the field and more than 70,000 larvae were tested in laboratory feeding experiments to determine if they were resistant. This extensive monitoring showed that the percentage of resistant insects increased from one percent of the population in 2010 to 5.5 percent in 2013.

The field data imply that the natural refuges of non-Bt crops other than cotton delayed resistance with an effect similar to that of a 56 percent non-Bt cotton refuge, just as the model predicted.

"Our results mean we are getting a better understanding of what is going on," Tabashnik said. "We'd like to encourage further documentation work to track these trends. The same kind of analysis could be applied in areas in the U.S. where the natural refuge strategy is used.

"Natural refuges help, but are not a permanent solution," he added. "The paper indicates that if the current trajectory continues, more than half of the cotton bollworm population in northern China will be resistant to Bt cotton in a few years."

To avoid this, the authors recommend switching to cotton that produces two or more Bt toxins and integrating Bt cotton with other control tactics, such as biological control by predators and parasites.

"The most important lesson is that we don't need to choose between biotechnology and traditional agriculture," Tabashnik said. "Instead, we can use the best practices from both approaches to maximize agricultural productivity and sustainability."

Source:University of Arizona

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New insights into origins of agriculture could help shape future of food

Wheat field (stock image). Agricultural decisions made by our ancestors more than 10,000 years ago could hold the key to food security in the future, according to new research by the University of Sheffield. Credit: © igor / Fotolia

Agricultural decisions made by our ancestors more than 10,000 years ago could hold the key to food security in the future, according to new research by the University of Sheffield.

Scientists, looking at why the first arable farmers chose to domesticate some cereal crops and not others, studied those that originated in the Fertile Crescent, an arc of land in western Asia from the Mediterranean Sea to the Persian Gulf.

They grew wild versions of what are now staple foods like wheat and barley along with other grasses from the region to identify the traits that make some plants suitable for agriculture, including how much edible seed the grasses produced and their architecture.

Dr Catherine Preece, who worked on the study with colleagues from the University's Department of Animal and Plant Sciences and Department of Archaeology, said: "Our results surprised us because numerous other grasses that our ancestors ate, but we do not, can produce just as much seed as wild wheat and barley. It is only when these plants are grown at high densities, similar to what we would find in fields, that the advantage of wild wheat and barley is revealed."

The study identified two key characteristics shared by the wild relatives of current crop plants. Firstly they have bigger seeds, which means they grow into bigger seedlings and are able to get more than their fair share of light and nutrients, and secondly, as adult plants they are less bushy than other grasses and package their big seeds onto fewer stems. This means crop wild relatives perform better than the other wild grasses that they are competing with and are better at growing close together in fields, making them ideal for using in agriculture.

"The results are important because our expanding human population is putting increasing demands on food production," said Dr Preece.

"Before humans learnt how to farm, our ancestors ate a much wider variety of grasses. If we can understand what traits have made some grasses into good crops then we can look for those characteristics in other plants and perhaps identify good candidates for future domestication."

She added: "To shape the future we must understand the past, so the more we can discover about the origins of agriculture, the more information we will have to help us tackle the challenges that face modern day food production."

So far the researchers have been conducting their experiments in greenhouses and their results indicate that the traits affecting how plants compete with each other are crucial factors to determining the success of a crop.

The team now plan to observe how the plants interact in their natural environment by growing them in experimental fields in Turkey, the heart of the Fertile Crescent. They hope that their experiments will yield another crop of important results.

"Cereal breeders are taking an increasing interest in modern crops' wild relatives as a source of useful traits that may help to increase yields or increase resilience to climate change, and our work should help in this process," said Dr Preece.

Dr Preece presented the results of this study to the joint British Ecological Society and the French Ecological Society 11 December 2014 in the Grand Palais, Lille.

Source: University of Sheffield

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Invasive plant wins competition against its native cousin

This iamge depicts root nodules. Credit: University of Illinois

Because of its aggressive behavior and its harmful effects, the invasive prairie plant Lespedeza cuneata has been added to several noxious weed lists. Research at the University of Illinois on how soil bacteria interact with the plants' roots to form nodules that fix nitrogen demonstrated that the invasive variety had superior performance when pitted against the native plant variety Lespedeza virginica.

"We expected Lespedeza cuneata to be a strong competitor when up against its native cousin that's planted primarily for prairie restoration," said U of I microbial ecologist Tony Yannarell. "There are a number of studies showing that L. cuneata grows quickly, is able to shade out its competitors, and has a high rate of nitrogen fixation, which allows it to 'self-fertilize' on unproductive soils."

Yannarell explained that Lespedeza plants establish a "partnership" with bacteria in the soil to form nodules that fix nitrogen. "We wanted to demonstrate that the partners in this symbiosis matter," he said.

Because the nitrogen-fixing gene is in the bacteria, the first step in the research was to identify bacteria that have the gene. "We started with isolating a pool of 50 bacteria [from the root nodules of invasive and native Lespedezas] and discovered that some of them weren't traditional nodule-forming bacteria."

Ultimately, seven bacteria were identified and used in a three-month greenhouse experiment in which various combinations of native and invasive varieties of Lespedeza were grown together in pots. Of the seven, five bacteria were found to benefit the invader and two did not benefit either of the plant varieties.

"We were hoping to be able to change the degree of competitiveness by using different varieties of Lespedeza by varying the bacteria," Yannarell said. "It turned out that none of the bacteria seemed to be better for the native plant.

"A really intriguing pattern that we found is that a lot of these strains of bacteria that are good for the invader belong to the Bradyrhizobium genus of bacteria that's been shown in other parts of the world to be good at fixing nitrogen so this was one more confirmation of that information," Yannarell said.

Yannarell said that this study provides yet another piece in the ecological puzzle.

The invasive Lespedeza cuneata was intentionally brought into the United States from Japan near the end of the 1800s. At the time, people liked its nitrogen-fixing capacity and soil fertilization. It was intended to be used to stabilize river banks and rehabilitate poor soil. Yannarell said that it has been recommended as wildlife forage, and some think that it has tannins that can act as a deworming treatment for goats. Now, however, it's considered to be a noxious weed that grows in the South and Midwest. It is commonly called silky bush clover.

Yannarell stressed that there are a lot of different species of Lespedeza that are native to North America and indicative of high-quality prairie. Although Lespedeza cuneata isn't a plant that would be intentionally planted by prairie restorationists, it has been seen in prairie seed mixes.

"Invasive Lespedeza cuneata and native Lespedeza virginica experience asymmetrical benefits from rhizobial symbionts," was published in Plant and Soil and was co-authored by Lingzi Hu, Ryan R. Busby, and Dick L. Gebhart. The work was supported by a grant from the U.S. Army Engineer Research and Development Center and by the Cooperative State Research, Education and Extension Service, U.S. Department of Agriculture.

Source: University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)

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This image shows a panda eating in China's Wolong Nature Reserve. Pandas habitat choices center around the ready availability of bamboo -- lots of bamboo. Credit: Sue Nichols, Michigan State University

Walter Dodds, university distinguished professor of biology (pictured), and Allison Veach, doctoral student in biology, are researching grassland streams and the expansion of nearby woody vegetation. They have studied 25 years of data on the Konza Prairie Biological Station and found that increasing fire frequency reduces the rate of woody vegetation expansion. Credit: Image courtesy of Kansas State University

Two Kansas State University biologists are studying streams to prevent tallgrass prairies from turning into shrublands and forests.

By looking at 25 years of data on the Konza Prairie Biological Station, Allison Veach, doctoral student in biology, Muncie, Indiana, and Walter Dodds, university distinguished professor of biology, are researching grassland streams and the expansion of nearby woody vegetation, such as trees and shrubs. They have found that burn intervals may predict the rate of woody vegetation expansion along streams.

Their latest research appears in the peer-reviewed journal PLOS ONE in an article "Fire and Grazing Influences on Rates of Riparian Woody Plant Expansion along Grassland Streams."

Grasslands in North America and across the globe are rapidly disappearing, Veach said, and woody plants are expanding and converting grasslands into forest ecosystems. This change in environment can affect stream hydrology and biogeochemistry, said Dodds, who has studied streams and watersheds on the Konza prairie for more than 20 years.

"This is an important issue regionally, because as trees expand into these grassland areas, people who are using grassland for cattle production have less grass for animals, too," Dodds said.

In their latest research, the biologists studied 25 years of aerial photography on Konza and observed the expansion of trees and shrubs in riparian areas, which include areas within 30 meters of streambeds. The researchers focused on three factors that affect grassland streams: burn intervals; grazers, such as bison; and the historical presence of woody vegetation.

Their analysis revealed an important finding: Burn intervals predicted the rate of woody vegetation expansion. Burning every one to two years slowed the growth of trees and shrubs, Veach said.

"Although we can reduce woody expansion by burning more frequently, we can't prevent it from occurring over time," Veach said. "Woody plant encroachment may not be prevented by fire alone."

The research shows the importance of burning to maintain the tallgrass prairie, Dodds said. While burning can help to slow the expansion of trees and shrubs, additional actions are need to maintain quickly disappearing grassland ecosystems.

"It's clear from this research that if you don't burn at all, these grassland streams basically are going to switch to forests and will not be grassland streams anymore," Dodds said.

Dodds and Veach also found that bison do not significantly affect woody vegetation expansion along streams. Previous Konza research has shown that bison do not spend significant time near stream areas, so they may not influence the growth of nearby trees and shrubs, Veach said.

Woody vegetation also may be expanding in grasslands because of more carbon dioxide in the atmosphere, Dodds said. Grasses and trees compete for carbon dioxide, and grasses are much better at conserving water and efficiently using carbon dioxide. As atmospheric carbon dioxide levels increase, it becomes easier for trees to gather carbon dioxide and gives them a growing advantage over grasses.

"The tallgrass prairie is almost nonexistent on the globe," Veach said. "In order for us to preserve tallgrass prairie, we need to look at woody encroachment because it has been an issue. Things like no fire or differences in climate change may allow woody plant species to competitively take over grasslands."

The biologists plan to continue studying water quality and quantity issues at Konza. Konza is an 8,600-acre tallgrass prairie ecological research site jointly owned by the university and The Nature Conservancy.

Source:  Kansas State University

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A global surge of great earthquakes from 2004-2014 and implications for Cascadia

The last ten years have been a remarkable time for great earthquakes. Since December 2004 there have been no less than 18 quakes of Mw8.0 or greater -- a rate of more than twice that seen from 1900 to mid-2004. Hundreds of thousands of lives have been lost and massive damage has resulted from these great earthquakes. But as devastating as such events can be, these recent great quakes have come with a silver lining: They coincide with unprecedented advances in technological and scientific capacity for learning from them.

"We previously had very limited information about how ruptures grow into great earthquakes and interact with regions around them," said seismologist Thorne Lay of the University of California at Santa Cruz. "So we are using the recorded data for these recent events to guide our understanding of future earthquakes. We've gained a new level of appreciation for how one earthquake can influence events in other zones."

High on the list of areas ripe for a great quake is Cascadia, the Pacific Northwest, where the risk for great quakes had long been under appreciated. Evidence began surfacing about 20 years ago that there had been a great quake in the region in the year 1700. Since then the view of the great quake risk in Cascadia has shifted dramatically.

"We don't know many details about what happened in 1700," said Lay. There were no instruments back then to observe and record it. And so the best way to try and understand the danger and what could happen in Cascadia is to study the recent events elsewhere.

Over the last decade Lay and his colleagues have been able to gather fine details about these giant earthquakes using data from an expanded global networks of seismometers, GPS stations, tsunami gauges, and new satellite imaging capabilities such as GRACE, InSAR, and LandSAT interferometry. Among the broader conclusions they have come to is that great quakes are very complicated and idiosyncratic. Lay will be presenting some of those idiosyncrasies at the meeting of the Geological Society of America in Vancouver on Oct. 21.

"What we've seen is that we can have multiple faults activated," said Lay. "We've seen it off Sumatra and off Japan. Once earthquakes get going they can activate faulting in areas that were thought not physically feasible."

The great Sumatra-Andaman earthquake of Dec. 26, 2004, for instance, unzipped a 1,300 kilometer long segment of the subduction zone and unleashed one of history's most destructive, deadly tsunamis. Much of the rupture was along a region with very limited plate convergence. In Japan, the Kuril Islands, and the Solomon Islands, great mega-thrust ruptures have ruptured portions of the subduction zones that were thought too warm or weak to experience earthquakes.

"These earthquakes ruptured right through areas that had been considered to have low risk," said Lay. "We thought that would not happen. But it did, so we have to adjust our understanding."

Perhaps the best recent analogy to Cascadia is off the coast of Iquique, Chile, said Lay. There had been a great quake in 1877, and a conspicuous gap in quakes ever since. Like the 1700 Cascadia earthquake, there is little data for the 1877 event, which killed more than 2,500 people. In both subduction zones, the converging plates are thought to be accumulating strain which could be released in a very large and violent rupture. On April 1 of this year, some of that strain was released offshore of Iquique. There was a Mw8.1 rupture in the northern portion of the seismic gap. But it involved slip over less than 20 percent of the region that seismologists believe to have accumulated strain since 1877.

"We have no idea why only a portion of the 1877 zone ruptured," said Lay. "But clearly, 80 percent of that zone is still unruptured. We don't have a good basis for assessment of how the rest will fail. It's the same for Cascadia. We don't know if it always goes all at once or sometimes in sequences of smaller events, with alternating pattern. It is prudent to prepare for the worst case of failure of the entire region in a single event, but it may not happen that way every time."

What is certain is that studying these recent big earthquakes has given geophysicists the best information ever about how they work and point to new ways to begin understanding what could be in Cascadia's future.

Source: Geological Society of America

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