It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, November 27, 2020
High genomic variability predicts success in desert tortoise refugees; could inform conservation
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE
Tortoise refugees with the highest genetic variation are far more likely to survive conservation translocation than tortoises whose genetic diversity is lower, according to a new study. The findings suggest that translocation efforts should account for genetic variation when selecting target individuals rather than focusing solely on those determined to be most geographically or genetically similar to the target populations. Human activity and climate change are driving record numbers of species towards extinction and represent a challenge that is being addressed by a myriad of conservation efforts worldwide. One conservation strategy employed to preserve threatened species is through translocation of individual plants and animals to areas where they've become locally extinct or to new locations where they might bolster declining resident populations. While the approach is becoming increasingly common, it is often reserved as a last resort as the long-term success is often quite poor. An ongoing debate in this area relates to whether such efforts are most successful when they target individuals from environmentally similar regions or genetically close target populations, or when they focus on overall genetic diversity. To test these hypotheses, Peter Scott and colleagues used a long-term dataset of displaced Mojave Desert Tortoises - many previously captive pets - brought to the Desert Tortoise Conservation Center's translocation site in Nevada. Scott et al. analyzed genomic data for 166 desert tortoise refugees that either survived or died over a period of twenty years and found that neither geographical distance nor genetic similarity had any effect on post-translocation survival. Instead, the greatest predictor for success was heterozygosity - individuals with the highest genomic variation survived at much higher rates than others. While the authors note that further research is needed to understand the reasons behind this increased survival, the new insights suggest ways to improve current translocation efforts.
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UCLA study of threatened desert tortoises offers new conservation strategy
Animals with more genetic variation are more likely to survive relocation
In Nevada's dry Ivanpah Valley, just southeast of Las Vegas, a massive unintended experiment in animal conservation has revealed an unexpected result.
From 1997 to 2014, the U.S. Fish and Wildlife Service moved more than 9,100 Mojave desert tortoises to the 100-square-kilometer (about 39 miles square) Large Scale Translocation Site. The newcomers, many of which were abandoned pets or had been displaced by development, joined nearly 1,500 desert tortoises already living there.
Conventional wisdom would suggest that tortoises from areas closest to the translocation site would fare best. But a new UCLA study, published today in Science, found no connection between the tortoises' place of origin and their chances of survival. It did, however, uncover a far better predictor.
Tortoises with lots of genetic variation were much more likely to survive after their relocation, said UCLA conservation ecologist Brad Shaffer, the study's senior author. Like most organisms, tortoises have two copies of their entire genome, with one copy from each parent. The more those copies differ from each other, the higher the organism's heterozygosity.
The researchers compared translocated tortoises that lived or died over the same time period after being relocated to the site. They found that survivors averaged 23% greater heterozygosity than those that perished. Simply put, tortoises with more genetic variation had higher survival rates.
"It flies in the face of what we know from other translocation studies, but lots of genetic variation was hands-down the best predictor of whether a tortoise lived or died," said Shaffer, a professor of ecology and evolutionary biology and director of the UCLA La Kretz Center for California Conservation Science. "Relocating endangered plants and animals is increasingly necessary to counteract the effects of climate change, and this gives us a new tool to increase survival rates."
Although the relationship between heterozygosity and survival was well supported by the study, it's unclear why greater genetic variation is linked to survival rates, said former UCLA postdoctoral scholar Peter Scott, the study's lead author.
"Potentially, individuals with higher heterozygosity have more genomic flexibility," said Scott, who is now an assistant professor at West Texas A&M University. "It's likely that tortoises with more variation have a better chance of having one copy of a gene that works really well in stressful or new environments compared to those individuals with two identical copies that only work really well in their environment of origin."
The researchers wanted to make tortoise conservation efforts more effective, and uncover trends that would help other species as well, Scott said.
"Oftentimes, the chances of success for relocating plants or animals is pretty dismal," he said. "We wanted to understand why, and use that understanding to increase survival."
Over the years, tortoises that were given up as pets, or removed from places like developments in suburban Las Vegas and solar farms in the desert, were surrendered to the U.S. Fish and Wildlife Service.
The agency took blood samples to screen for diseases and marked each animal before releasing them into the Ivanpah Valley site, which enabled the animals to be tracked in later surveys. The UCLA researchers sequenced blood samples drawn from 79 tortoises that were released to the site and were known to be alive in 2015, and from another 87 known to have died after they were released at the site.
Although the Large Scale Translocation Site provided an intriguing dataset, it's not the same as a controlled experiment. Additional studies would be needed to understand why more heterozygous tortoises had a higher survival probability and precisely how much of an increase in genetic variation improves a tortoise's odds of surviving.
"The only reason we could do this study was because the U.S. Fish and Wildlife Service was incredibly forward-thinking when they set up the translocation site and tracked who lived and died," Shaffer said. "Many died, and no one was happy about that. But we can learn a lot from that unfortunate result to help conservation management improve.
"When thinking about moving animals or plants out of danger, or repopulating an area emptied by wildfire, now we can easily and economically measure genetic variability to better gauge the survival probability of those translocated individuals. It's not the only criteria, but it's an important piece of the puzzle."
IMAGE: PACHODYNERUS NASIDENS ON 3D-PRINTED DE HAVILAND DASH-8 PITOT PROBE view more
CREDIT: HOUSE ET AL (2020) PLOS ONE, CC BY
Over a period of 39 months, invasive keyhole wasps (Pachodynerus nasidens) at the Brisbane Airport were responsible for 93 instances of fully blocked replica pitot probes - vital instruments that measure airspeed -- according to a study published November 30 in the open-access journal PLOS ONE by Alan House of Eco Logical Australia and colleagues. As noted by the authors, the results underscore the importance of risk-mitigating strategies, such as covering pitot probes when aircraft arrive and setting up additional traps to intercept the wasps.
Interactions between aircraft and wildlife are frequent and can have serious financial and safety consequences. But the risk posed by wildlife when aircraft are on the ground is much less understood, and specific threats posed by insects have not been quantified before. In the new study, House and his colleagues investigated the possible role of keyhole wasps in obstructing pitot probes at Brisbane Airport. A total of 26 wasp-related issues were reported at the airport between November 2013 and April 2019, in conjunction with a series of serious safety incidents involving pitot probes. In its native range in South and Central America and the Caribbean, the wasp is known to construct nests using man-made cavities, such as window crevices, electrical sockets, and of course, keyholes.
The researchers used 3D-printing technology to construct a series of replica pitot probes, which they mounted at four locations at the airport. All nests in these probes were made by keyhole wasps, and peak nesting occurred in the summer months. Nesting success (i.e., the proportion of nests producing live adults) was optimal between 24 and 31°C, and probes with apertures of more than 3 mm in diameter were preferred. The majority of nests were constructed in one area of the airport. The proportion of grassed areas within 1000 m of probes was a significant predictor of nesting, and the nest volume in pitot probes may determine the sex of emerging wasps. According to the authors, P. nasidens poses a significant risk to aviation safety, and further work is warranted to develop strategies for controlling or eradicating persistent populations of this adaptable, inventive, and highly mobile species.
The authors add: "We hope this research will bring attention to a little known but serious issue for air travel in tropical and sub-tropical regions. Having found its way across the Pacific Ocean, there is no reason to doubt that it could spread to other parts of Australia. The consequences of not managing this clever but dangerous pest could be substantial."
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Citation: House APN, Ring JG, Shaw PP (2020) Inventive nesting behaviour in the keyhole wasp Pachodynerus nasidens Latreille (Hymenoptera: Vespidae) in Australia, and the risk to aviation safety. PLoS ONE 15(11): e0242063. https://doi.org/10.1371/journal.pone.0242063
Funding: The funder (BAC) provided support in the form of salaries for authors [APNH, PPS, JGR] and provided access to the airport to conduct the experiment, co-designed the experiment and assisted in monitoring. Qantas (Matthew Hill is a paid employee of Qantas) made significant in-kind (but not financial) contributions to the project through professional advice and access to materials and 3D-printing facilities. the funders did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section.
Competing Interests: This work was commissioned and funded in its entirety by Brisbane Airport Corporation (JGR is a paid employee of BAC) to address a serious threat to aviation safety at the airport. No other sources of funding were received by the project team. BAC provided salaries to JGR, APNH and PPS. Ecosure (PPS) and Eco Logical Australia (APNH) (both consultancies) were engaged to provide professional ecological advice and devise and run a research program. Qantas (MJH is a paid employee of Qantas) made significant in-kind (but not financial) contributions to the project through professional advice and access to materials and 3D-printing facilities. There are no financial competing interests beyond these relationships. As the funder of the work, BAC (through JGR) provided access to the airport to conduct the experiment, co-designed the experiment and assisted in monitoring. All analysis and interpretation was done by Alan House. This does not alter our adherence to PLoS ONE policies on sharing data and materials.
IMAGE: A TRADITIONAL CHINESE MEDICINE PRACTITIONER SELECTING TREATMENTS. view more
Demystifying traditional Chinese medicine for conservationists could be the key to better protecting endangered species like pangolins, tigers and rhino, according to University of Queensland-led researchers.
UQ PhD candidate Hubert Cheung said efforts to shift entrenched values and beliefs about Chinese medicine are not achieving conservation gains in the short term.
He said a better understanding of traditional practices was critical for conservationists to form more effective strategies.
"The use of endangered species in traditional Chinese medicine threatens species' survival and is a challenge for conservationists," Mr Cheung said.
"Pushing messages of inefficacy, providing various forms of scientific evidence or promoting biomedical alternatives doesn't seem to be drastically influencing decisions and behaviours.
"And, although many practices and treatments continue to be criticised for lacking scientific support, the World Health Organization approved the inclusion of traditional Chinese medicine in its global compendium of medical practices last year.
"The challenge now is for conservationists to work proactively with practitioners and others in the industry to find sustainable solutions.
"However, most conservation scientists and organisations are unfamiliar with traditional Chinese medicine, which makes it difficult to devise effective and culturally-nuanced interventions."
The researchers have examined the core theories and practices of traditional Chinese medicine, in a bid to make it more accessible.
They hope their study - and the nuances within - will influence policy and campaigning.
"Today, traditional Chinese medicine is formally integrated into China's healthcare system, and has been central to China's response to the ongoing pandemic," Mr Cheung said.
"In fact, the Chinese government's COVID-19 clinical guidance has included recommendations for the use of a product containing bear bile, which has raised concerns among conservation groups."
UQ's Professor Hugh Possingham said traditional Chinese medicine was now not only entrenched in the social and cultural fabric of Chinese society, but also gaining users elsewhere.
"A better understanding of traditional Chinese medicine will empower conservationists to engage more constructively with stakeholders in this space," Professor Possingham said.
"We're hoping that this work can help all parties develop more effective and lasting solutions for species threatened by medicinal use."
CAPTION
Traditional Chinese medicine utilises a variety of ingredients derived from plants, animals and fungi. Some of these come from threatened species, like these horns of critically endangered saiga antelope.
Irreversible hotter and drier climate over inner East Asia
Heatwaves pushing Mongolia's climate to a tipping point
IMAGE: TREE-RING DATA FROM SIBERIAN LARCH AND OTHER TREE SPECIES SHOW THAT HEATWAVES AND SOIL DRYING OF THE MONGOLIAN PLATEAU HAVE ACCELERATED IN THE PAST TWO DECADES. THE REGION'S CLIMATE REGIME... view more
CREDIT: KEN SHONO, UNSPLASH
Mongolia's semi-arid plateau may soon become as barren as parts of the American Southwest due to a "vicious cycle" of heatwaves -- that exacerbates soil drying, and ultimately produces more heatwaves -- according to an international group of climate scientists.
Writing in the journal Science, the researchers warn that heatwaves and concurrent droughts have increased significantly during the past two decades, with troubling implications for the future. Using tree-ring data, which offer a glimpse of regional climates from before modern weather logs, the researchers developed heatwave and soil moisture records that suggest recent consecutive years of record high temperatures and droughts are unprecedented in more than 250 years.
According to the study's findings, the record high temperatures in the region are accelerated by soil drying, and together these changes are magnifying the decline of soil water. "The result," coauthor Deliang Chen at Sweden's University of Gothenburg said, "is more heatwaves, which means more soil water losses, which means more heatwaves -- and where this might end, we cannot say."
When soil is wet, evaporation cools air at the surface. However, when soil no longer has any moisture, heat transfers directly to the air. In their paper, Abrupt shift to hotter and drier climate over inner East Asia beyond the tipping point, the authors state that in the past 260 years, only recent decades "show significant anticorrelation between heatwave frequency and soil moisture, alongside a radical decline in soil moisture fluctuation." The scientists note that a series of recent heatwaves in Europe and North America reveal the connection with near-surface air and soil moisture and suggest that "the semi-arid climate of this region has entered a new regime in which soil moisture no longer mitigates anomalously high air temperature."
Already, lakes in the Mongolian Plateau have experienced rapid reductions. As of 2014, researchers from China had documented a 26 percent decrease in the number of lakes greater than one square kilometer in size, with even larger average reductions in size for the region's largest lakes.
"Now we are seeing that it isn't just large bodies of water that are disappearing," said corresponding author Jee-Hoon Jeong of Chonnam National University in South Korea. "The water in the soil is vanishing, too."
"This may be devastating for the region's ecosystem which is critical for the large herbivores, like wild sheep, antelope and camels," Peng Zhang, the study's lead author and a researcher at the University of Gothenburg. "These amazing animals already live on the edge, and these impacts of climate change may push them over."
CAPTION
A cross-section of Scots pine (Pinus sylvestris L.), one of the tree species used for the soil moisture reconstruction in inner East Asia.
Coauthor Jin-Ho Yoon, of the Gwangju Institute of Science and Technology in South Korea, noted that the hundreds of years of tree-ring data make it clear that the confluence of increased summer heatwaves and severe droughts are unique in the context of the past 260 years. Coauthor Hans Linderholm, from the University of Gothenburg, said the trees used in the analysis appear to "feel" the heatwaves throughout their lifetimes.
"The conifer trees respond strongly to anomalously high temperatures," Linderholm said. "By examining their growth rings, we can see their response to the recent heatwaves, and we can see that they do not appear to have experienced anything like this in their very long lives."
Tree rings examined in the study were mainly collected from the Mongolian Plateau, which suggests that the increasing heat is affecting plants even at high elevations.
Daniel Griffin, of the University of Minnesota's Department of Geography, Environment and Society, who is not involved in this study but has reviewed the paper, said that long-term perspective from these tree-ring records illustrates a nuanced picture of the changing climate that is now afflicting large swaths of the inner East Asia region.
"It is one thing to recognize that the "normal" climate conditions are changing. However, what concerns me the most is thinking about the extreme events of the future: how severe might those become?" asked Griffin. "And if the "new normal" is extremely hot and dry by historical standards, then future extremes may well be unlike anything previously witnessed."
While warmer and drier trends are observed over Europe and Asia, Mongolia and its surrounding countries are particularly interesting to climate scientists because this Inner East Asia region has a very direct link to global atmospheric circulations.
"Summer atmospheric waves tend to create a high-pressure ridge pattern around Mongolia that can persist for weeks, triggering heatwaves," explained coauthor Simon Wang of Utah State University in the United States. "The warming climate is amplifying these atmospheric waves, increasing the chance of prolonged or intensified high-pressure to occur over Mongolia and this can also have ramifications across the Northern hemisphere."
CAPTION
Changes in the region's ecosystem, driven by heatwaves and drought, could be devastating for large herbivores, such as wild sheep, antelope and camels.
"Such large-scale atmospheric force is further amplified by local interactions with the land surface," coauthor Hyungjun Kim, from the University of Tokyo in Japan, pointed out. "An even worse problem may have already occurred in which an irreversible feedback loop is triggered and is accelerating the region toward a hotter and drier future."
Indeed, the researchers have observed that recent heatwaves have come with even drier and hotter air, under the strengthened high-pressure ridge, than the heatwaves of the past.
The research team found that the warming and drying concurrence seems to approach a "tipping point" and is potentially irreversible, which may push Mongolia into a permanent state of aridness.
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This research appears in the November 27, 2020, issue of Science, published by AAAS, the world's largest general scientific organization. See http://www.sciencemag.org, and also http://www.aaas.org.
Zhang, P., J.-H. Jeong, J.-H. Yoon, H. Kim, S.-Y. Wang, H. W. Linderholm, K. Fang, X. Wu, D. Chen, 2020: Abrupt shift to hotter and drier climate over inner East Asia beyond the tipping point. Science, in press (under em
In fire-prone West, plants need their pollinators -- and vice versa
IMAGE: FIREWEED (CHAMERION ANGUSTIFOLIUM) BLOOMS IN YELLOWSTONE NATIONAL PARK, MONTANA. NEW RESEARCH HIGHLIGHTS THE IMPORTANCE OF PLANT-POLLINATOR INTERACTIONS IN RESTORING ECOSYSTEMS IN WHICH NATURAL WILDFIRE REGIMES HAVE BEEN ALTERED OR SUPPRESSED... view more
CREDIT: JONATHAN MYERS, WASHINGTON UNIVERSITY IN ST. LOUIS
2020 is the worst fire year on record in the United States, with nearly 13 million acres burned, 14,000 structures destroyed and an estimated $3 billion spent on fire suppression -- and counting. At the same time, certain land managers have invested huge amounts of time and resources toward restoring fire through "controlled burn" approaches.
In the face of heartbreaking losses, effort and expense, scientists are still grappling with some of the most basic questions about how fire influences interactions between plants and animals in the natural world.
A new study grounded in the northern Rockies explores the role of fire in the finely tuned dance between plants and their pollinators. Published Nov. 25 in the Journal of Ecology, the findings from researchers at Washington University in St. Louis, Marquette University, Montana State University and The Wilderness Society are particularly significant in light of recent reports about the rapid and widespread decline of insects globally.
"A large number of studies have looked at how fire affects plants, or how fire affects animals. But what is largely understudied is the question of how fire affects both, and about how linkages within those ecological networks might respond to fire disturbance," said Jonathan Myers, associate professor of biology in Arts & Sciences at Washington University, a co-author of the study.
The researchers discovered that wildfire disturbance and plant-pollinator interactions are both important in determining where plants take root and where pollinators are found. But in burned landscapes, plant-pollinator interactions are generally as important or more important than any other factor in determining the composition of species present.
The importance of flowering-plant species in determining the composition of pollinator species doubled to quadrupled following wildfire. In addition, the importance of pollinators in determining plant composition nearly doubled following wildfire.
"Clearly, pollinators perform a valuable ecosystem service for humans by pollinating all our crops. In intact natural ecosystems, they perform an equally valuable service," said Joseph LaManna, assistant professor of biological sciences at Marquette University, first author of the study. "What we are seeing is that plant and pollinator linkages become even more important in disturbed or burned landscapes. These connections are important for restoring ecosystems in which natural wildfire regimes have been altered or suppressed by human activities.
"And as climate change increases the frequency and intensity of wildfires, the potential for biodiversity loss -- for losses of individual plant or pollinator species -- is going to be even more profound than we anticipated," he said.
Feeling the burn
Wildfire in the northern Rockies can be ignited by lightning -- but more and more, it is started by people.
Historically, wildfires tended to burn hot in some spots and cold in others, resulting in a patchwork or mosaic of differing levels of fire disturbance. But with rising global temperatures, the plant debris and other materials that fuel fires are drying out. That trend combined with decades of active fire suppression has resulted in a shift from a majority mixed-severity wildfire regime to today's high-severity blazes.
For this study, co-author Laura Burkle at Montana State University led the field inventories of plants and pollinators at 152 plots in Montana representing a wildfire gradient including plots with no recent wildfire (unburned), mixed-severity wildfire and high-severity wildfire. LaManna and Myers worked with Burkle and Travis Belote of The Wilderness Society to analyze the data.
At the sites they compared, the scientists found that the number of individual bees, flies and butterflies -- and the flowering plants they frequent -- were higher in parts of the landscape that had burned, as opposed to those that hadn't burned.
However, increases were greater in areas that had experienced mixed-severity wildfire, which leaves some vegetation intact in a mosaic of habitat types, as opposed to high-severity wildfire, which largely removes all vegetation and can damage the soil and seed bank.
For example, flowering-plant abundances increased more than 10-fold in mixed-severity wildfire and more than nine-fold in high-severity wildfire compared with unburned areas. Overall the researchers identified 329 pollinator species and 193 flowering-plant species.
"Oftentimes, the public perception about fire in general is that it is bad. But it was impressive how much higher the abundances of both plants and pollinators were -- as well as the number of species -- in the burned landscapes compared with the unburned landscapes," Myers said.
Leave it to the bees
Although this study shows that fire increased abundances and species diversity of pollinators and flowering plants overall, the intensity of the fire matters. Hotter, high-severity burns can eliminate landscape features that pollinators require, like stumps or woody debris for nesting. Mixed-severity wildfire is most beneficial.
Around the world, pollinator populations are in decline. The northern Rockies are no exception to this troubling trend.
"Thanks to this project, we now have very in-depth knowledge of local pollinator communities, especially the bee communities," Burkle said. "One of the benefits of these data is to be able to provide expert knowledge about declining pollinator species and species of concern, like the Western Bumble Bee (Bombus occidentalis), which is currently being considered for federal listing under the Endangered Species Act.
"When we think about patterns of biodiversity across space, we typically consider different groups of species separately," she said. "In our case, we might consider patterns of plant diversity separately from patterns of pollinator diversity. But our study provides solid evidence that -- above and beyond the influence of disturbances like wildfires -- the relationships that plants have with pollinators are strong contributors to these patterns of biodiversity.
"This means that biotic interactions among species are important and will need to be considered more explicitly in conservation actions, like plans for species range shifts with climate change."
Accelerating extinction
Global climate change is likely to increase the frequency and intensity of wildfires in many other regions -- as it has in the mountain West, the researchers said.
The findings from this study suggest that this could possibly result in additional losses of vulnerable species.
"We may see wildfire accelerating co-extinction events where you lose a pollinator and then you lose all of the plants that the pollinator depended on -- and then you lose more pollinators that were associated with those plants, and so on," LaManna said. "You have a potential for a chain of losses."
Overall, this research advances understanding of how and why wildfire affects conservation, land management and restoration of forest ecosystems. It also shows that ecological models that predict how species will respond under various climate change scenarios also should consider biological interactions within food webs, Myers said.
"By sharing our findings with federal land managers across the region, we hope to contribute to management plans, with the dual aim of maintaining biodiversity of plants and pollinators while restoring environmental complexity representative of historical fire regimes," Myers said.
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Novel chemical process a first step to making nuclear fuel with fire
IMAGE: COMBUSTION SYNTHESIS OF LNBTA COMPOUND. view more
CREDIT: LOS ALAMOS NATIONAL LABORATORY.
LOS ALAMOS, N.M., November 24, 2020 -- Developing safe and sustainable fuels for nuclear energy is an integral part of Los Alamos National Laboratory's energy security mission. Uranium dioxide, a radioactive actinide oxide, is the most widely used nuclear fuel in today's nuclear power plants. A new "combustion synthesis" process recently established for lanthanide metals -- non-radioactive and positioned one row above actinides on the periodic table -- could be a guide for the production of safe, sustainable nuclear fuels.
"Actinide nitride fuels are potentially a safer and more economical option in current power-generating systems," said Bi Nguyen, Los Alamos National Laboratory Agnew postdoc and lead author of research recently published in the journal Inorganic Chemistry, which was selected as an American Chemical Society Editors' Choice Featured Article.
"Nitride fuels are also well suited to future Generation IV nuclear power systems, which focus on safety, and feature a sustainable closed reactor fuel cycle. Actinide nitrides have superior thermal conductivity compared to the oxides and are significantly more energy dense," said Nguyen. Nitrides are a class of chemical compounds that contain nitrogen, versus oxides, which contain oxygen.
Actinide nitride fuels would provide more safety and sustainability because of their energy density, offering up more energy from less material, as well as better thermal conductivity -- allowing for lower temperature operations, giving them a larger margin to meltdown under abnormal conditions.
Actinide nitrides, however, are very challenging to make and the production of large amounts of high purity actinide nitrides continues to be a major impediment to their application. Both actinides and lanthanides are at the bottom of the periodic table and potential methods to make actinide materials are typically first tested with the lanthanides because they behave similarly, but are not radioactive.
Los Alamos National Laboratory and Naval Research Laboratory scientists discovered that LnBTA [lanthanide bis(tetrazolato)amine] compounds can be burned to produce high-purity lanthanide nitride foams in a unique technique called combustion synthesis. This method uses a laser pulse to initiate dehydrated LnBTA complexes, which then undergo a self-sustained combustion reaction in an inert atmosphere to yield nanostructured lanthanide nitride foams. This work was funded by the Laboratory Directed Research and Development (LDRD) program.
LnBTA compounds are easily prepared in bulk and their combustion is readily scalable. There is an ongoing collaboration between the Laboratory's Weapons Modernization and Chemistry divisions to examine actinide analogues for combustion synthesis of actinide nitride fuels.
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The research team includes Nguyen, David Chavez, Bryce Tappan, and Alexander Mueller of the Explosives Science and Shock Physics group, Jacqueline Veauthier and Jaqueline Kiplinger of the Inorganic Isotope and Actinide group, Brian Scott of Materials Synthesis and Integrated Devices group, and Damon Parrish of the Naval Research Laboratory.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is managed by Triad, a public service oriented, national security science organization equally owned by its three founding members: Battelle Memorial Institute (Battelle), the Texas A&M University System (TAMUS), and the Regents of the University of California (UC) for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.
LA-UR-20-29589
German researchers compile world's largest inventory of known plant species
Catalogue vastly expands global knowledge of plant diversity
GERMAN CENTRE FOR INTEGRATIVE BIODIVERSITY RESEARCH (IDIV) HALLE-JENA-LEIPZIG
IMAGE: LEIPZIG IS HOST TO THE OLDEST BOTANICAL GARDEN IN GERMANY. ON AN AREA OF ONLY THREE HECTARES, AROUND 6500 OF THE 350,000 PLANT SPECIES WORLDWIDE GROW HERE. view more
CREDIT: SWEN REICHHOLD
Leipzig could mean for the future of plant taxonomy what Greenwich meant for world time until 1972: it could become the reference city for correct scientific plant names. In an outstanding feat of research, the curator of the Botanical Garden of Leipzig University, Dr Martin Freiberg, and colleagues from iDiv and UL have compiled what is now the largest and most complete list of scientific names of all known plant species in the world. The Leipzig Catalogue of Vascular Plants (LCVP) enormously updates and expands existing knowledge on the naming of plant species, and could replace The Plant List (TPL) - a catalogue created by the Royal Botanic Gardens, Kew in London which until now has been the most important reference source for plant researchers.
"In my daily work at the Botanical Garden, I regularly come across species names that are not clear, where existing reference lists have gaps," said Freiberg. "This always means additional research, which keeps you from doing your actual work and above all limits the reliability of research findings. I wanted to eliminate this obstacle as well as possible."
World's most comprehensive and reliable catalogue of plant names
With 1,315,562 scientific names, the LCVP is the largest of its kind in the world describing vascular plants. Freiberg compiled information from accessible relevant databases, harmonized it and standardised the names listed according to the best possible criteria. On the basis of 4500 other studies, he investigated further discrepancies such as different spellings and synonyms. He also added thousands of new species to the existing lists - species identified in recent years, mainly thanks to rapid advances in molecular genetic analysis techniques.
The LCVP now comprises 351,180 vascular plant species and 6160 natural hybrids across 13,460 genera, 564 families and 84 orders. It also lists all synonyms and provides further taxonomic details. This means that it contains over 70,000 more species and subspecies than the most important reference work to date, TPL. The latter has not been updated since 2013, making it an increasingly outdated tool for use in research, according to Freiberg.
"The catalogue will help considerably in ensuring that researchers all over the world refer to the same species when they use a name," says Freiberg. Originally, he had intended his data set for internal use in Leipzig. "But then many colleagues from other botanical gardens in Germany urged me to make the work available to everyone."
LCVP vastly expands global knowledge of plant diversity
"Almost every field in plant research depends on reliably naming species," says Dr Marten Winter of iDiv, adding: "Modern science often means combining data sets from different sources. We need to know exactly which species people refer to, so as not to compare apples and oranges or to erroneously lump different species." Using the LCVP as a reference will now offer researchers a much higher degree of certainty and reduce confusion. And this will also increase the reliability of research results, adds Winter.
"Working alone, Martin Freiberg has achieved something truly incredible here," says the director of the Botanical Garden and co-author Prof Christian Wirth (UL, iDiv). "This work has been a mammoth task, and with the LCVP he has rendered an invaluable service to plant research worldwide. I am also pleased that our colleagues from iDiv, with their expertise in biodiversity informatics, were able to make a significant contribution to this work."
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This research was in part supported by the DFG - Deutsche Forschungsgemeinschaft (FZT-118).
Tree rings capture an abrupt irreversible shift in east Asia's climate
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE
The abrupt shift to hotter and drier conditions over inner East Asia is unprecedented and may herald an irreversible shift to a new climate regime for the region, according to a new study. The findings reveal a positive feedback loop fueled by declining soil moisture, which may have nudged the area's climate over an important tipping point. Extreme heatwaves and droughts are two of society's most pressing concerns as climate change driven by human activity continues unabated. Global warming has already led to recent and rapid shifts in climate worldwide, including inner East Asia, which has experienced some of the most pronounced heatwave-drought concurrences in recent decades. It's thought that such abrupt and substantial changes represent the crossing of critical thresholds within the climate system and signal irreversible shifts from one climate regime to another. But, identifying tipping points and new climate norms is difficult; not only does it require a thorough understanding of a region's natural climate variability over timescales that often exceed available records, regime shifts are likely triggered by complex interactions between a variety of poorly understood factors in the highly dynamic climate system. To determine whether the heatwave-drought trends observed in inner East Asia indeed exceed the range of natural climate variability, Peng Zhang and colleagues used tree-ring data to reconstruct a record of heatwave frequency and soil moisture for the region spanning the past 260 years. Zhang et al. found that the rise in concurrent heatwave-drought events over the last two decades is unique and beyond the natural variability revealed by their centuries-long record. What's more, the authors demonstrate that the rise in heatwave-drought events may be caused by a positive feedback loop between decreasing soil moisture and increasing surface warming - a pattern that's potentially the start of an irreversible trend that's likely to produce more frequent and severe events. While much remains to be understood about the occurrence and mechanisms of climate regime shifts, developing trustworthy long-term climate records is crucial in detecting changes in the interactions of climate variables, discovering past shifts and predicting tipping points of potential future shifts, write Qi-Bin Zhang and Ouya Fang in a related Perspective.
Satellite images confirm uneven impact of climate change
University of Copenhagen researchers have been following vegetation trends across the planet's driest areas using satellite imagery from recent decades
University of Copenhagen researchers have been following vegetation trends across the planet's driest areas using satellite imagery from recent decades. They have identified a troubling trend: Too little vegetation is sprouting up from rainwater in developing nations, whereas things are headed in the opposite direction in wealthier ones. As a result, the future could see food shortages and growing numbers of climate refugees.
More than 40 percent of Earth's ecosystems are arid, an amount that is expected to increase significantly over the course of the 21st century. Some of these areas, such as those in Africa and Australia may be savannah or desert, where sparse rainfall has long been the norm. Within these biomes, vegetation and wildlife have adapted to making use of their scant water resources, but they are also extraordinarily vulnerable to climate change.
Using extensive imagery from satellites that monitor Earth every day, researchers from the University of Copenhagen's Department of Geosciences and Natural Resources Management have studied the evolution of vegetation in arid regions. Their conclusion is unequivocal:
"We observe a clear trend of arid areas developing in a negative direction in the most economically challenged countries. Here, it is apparent that the growth of vegetation has become increasingly decoupled from the water resources available and that there is simply less vegetation in relation to the amount of rainfall. The opposite is the case in the wealthiest countries," explains Professor Rasmus Fensholt of the Department of Geosciences and Natural Resource Management.
Worse in Asia and Africa, better in South America and Australia
The researchers analyzed 15 years worth of satellite imagery of vegetation and rainfall -- from 2000 to 2015. To compare the evolution of vegetation in arid regions of the world, the researchers removed precipitation totals from the equation. In other words, they produced a calculation that accounts for the fact that some regions received more rain in past decades, while other regions received less.
This provides a more accurate picture of ecosystem health, as human influences become easier to identify: In other words, whether resource use is balanced or whether an ecosystem's resources have been overexploited, with potentially fatal consequences -- as imbalanced systems may be irreparable.
"Here, our results demonstrate that in arid regions, particularly those in Africa and Asia, less vegetation grows for the amount of rainwater that falls, while more vegetation grows in arid areas of South America and Australia," says lead author Christin Abel, a postdoc at the Department of Geosciences and Natural Resource Management.
Infographic text: Areas with purple hues indicate where vegetation growth relative to rainfall is declining, while green hues reveal areas where vegetation has grown more than expected. White areas represent ecosystems where vegetation growth is in balance with the water resources available.
According to the researchers, there may be several explanations for why climate change and rising global temperatures are impacting vegetation in arid regions of the world's poorest countries. Among the most obvious is rapid population growth, in Africa for example, where there is an increasing need to exploit land that is otherwise poorly suited for agriculture. Doing so produces lower yields and puts increasing amounts of livestock on too little grass in already fragile ecosystems.
Conversely, vegetation in arid areas of the world's wealthier countries seems to be coping better with climate change. This is likely due to the intensification and expansion of larger farms, where more economic resources allow for, among other things, irrigation and fertilization.
Food crises and more climate refugees
As a result of climate change, future trends for the planet's poorest areas only seem to be getting worse. Forecasts point to an expansion of today's arid areas where they will make up a larger and larger share of our global ecosystems. This may result in more and more people being left without food and their needing to migrate.
"One consequence of declining vegetation in the world's poorer arid regions areas may be an increase in climate refugees from various African countries. According to what we've seen in this study, there is no indication that the problem will diminish in the future," explains Rasmus Fensholt.
For a number of years, satellite imagery has let researchers observe that, overall, it actually appears that the world's arid regions have become greener. However, when researchers look at how much vegetation arid areas in developing countries get in relation to rainfall amounts, the picture looks different.
"We have been pleased to see that, for a number of years, vegetation has been on an upwards trend in arid regions. But if we dig only a tiny bit deeper and look at how successfully precipitation has translated into vegetation, then climate change seems to be hitting unevenly, which is troubling," says Rasmus Fensholt.
