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 achievement cultures may kill students' interest in math -- especially for girls
A new study in Frontiers in Psychology suggests that high national math achievement combined with societal pressures may contribute to how well girls and boys like math. Past research has shown that achievement-driven cultures frequently correlate with less enthusiasm for learning subjects like math. This study of over 500,000 eighth graders from 50 countries is the first to show that girls appear even more susceptible to this effect, providing insights into how to close this gender gap.
"I think we need to look more critically at the idea that we can judge a country's school system mainly on the achievement level its pupils attain--other important aspects, such as pupils feeling interested in their schoolwork, may get lost in the process," says the author, Prof Kimmo Eriksson of Mälardalen University College and Stockholm University in Sweden. "It seems that cultures that promote high achievement in math may also tend to kill many pupils' interest in math schoolwork and I found that this negative effect of high-achievement culture was stronger among girls than among boys."
Eriksson used the results from the multinational Trends in Mathematics and Science Survey (TIMSS) from 2011 and 2015 to look at trends between math performance and students' interest levels. Although the survey had been performed in prior years, 2011 and 2015 were the first years when the survey included both a math test as well as a questionnaire about the students' interest in what they were learning.
The results showed that girls were significantly less interested in math in countries like Japan, Hong Kong, Sweden and New Zealand. But, surprisingly, the roles were reversed in countries like Oman, Malaysia, Palestine and Kazakhstan, where girls were far more engaged in the subject.
One particularly striking result was that whichever way national interest levels trended, the effect was more pronounced among girls. Eriksson named this effect 'female amplification' and suggests that this may be due to girls' stronger tendency to conform to peer influence.
It is important to note that these findings only imply correlation. Additional research is needed to better understand the underlying factors that cause these differences. But these observations may provide useful guidance for how to promote both math interest as well as achievement for girls and boys. Countries such as Singapore have also shown that it is possible to have both high interest and high performance, and further study of these school systems may help improve teaching methods elsewhere.
"By highlighting how girls' interest in schoolwork is especially sensitive to high-achievement culture, perhaps my work can make researchers and policy-makers recognize and address this challenge: How can schools promote high achievement in mathematics without killing pupils' interest in their schoolwork?" says Eriksson.
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RUDN University mathematicians applied 19th century ideas to modern computerized algebra systems
IMAGE: A TEAM OF MATHEMATICIANS FROM RUDN UNIVERSITY ADDED NEW SYMBOLIC INTEGRATION FUNCTIONALITY TO THE SAGE COMPUTERIZED ALGEBRA SYSTEM. THE TEAM IMPLEMENTED IDEAS AND METHODS SUGGESTED BY THE GERMAN MATHEMATICIAN KARL... view more
CREDIT: RUDN UNIVERSITY
A team of mathematicians from RUDN University added new symbolic integration functionality to the Sage computerized algebra system. The team implemented ideas and methods suggested by the German mathematician Karl Weierstrass in the 1870s. The results were published in the Journal of Symbolic Computation.
The first computer program capable of calculating integrals of elementary functions was developed in the late 1950s. By creating it, the developers confirmed that a computer could not only perform simple calculations but was also able to deal with tasks that required a certain degree of 'thinking'. Symbolic integration, i.e. integration that involves letters and abstract symbols instead of numbers, is an example of such a task. At the same time, scientists realized that neither humans nor computers were able to determine whether a given integral can be taken in elementary functions (provided such a human or computer used the methods studied in a university course of analysis and took a finite number of steps). Therefore, in the 1960s mathematicians working on symbolic integrators started to refer to methods that had been suggested by Liouville in the 1830s. From that time on, computer scientists have been tapping into the classic scientific heritage.
The calculation of primitives of algebraic functions is one of the bottlenecks in the process of integrator development. Before World War I, the integration of algebraic functions or Abelian integrals had been considered one of the most important issues in mathematics, but later on, it was forgotten. "Current computer algebra systems are able to fulfill even the most exotic requests of mathematical analysis students, but at the same time, many of these systems fail to recognize integrals in elementary functions. Only several packages allow for the integration of algebraic functions or with Abelian integrals, but their development stopped 15 years ago, and their functionality leaves much to be desired," says Mikhail Malykh, a Doctor of Science in Physics and Mathematics, and an assistant professor at the Department of Applied Informatics and Probability Theory, RUDN University.
One of the theories developed by the German mathematician Karl Weierstrass in the 1870s reduces the calculation of an integral of an algebraic function to finding a given set of known integrals of all three types. The initial integral is represented as a sum of standard integrals (this construction is knowns as the normal representation of an Abelian integral). The team from RUDN University confirmed that this representation is indicative of whether a given integral can be calculated in elementary functions. To confirm their theory, the mathematicians tested them on simple elliptical integrals using a software package that had been created by the team in 2017. The package helps calculate coefficients of the normal form of an integral. In the future, the team plans to conduct similar studies for a wider range of integrals.
"This work is just one step on our way to an ambitious goal: we want to express Weierstrass's theory of Abelian integrals and functions using the language of computer algebra and to implement it in the Sage system, giving researchers from all over the world free access to it," added Mikhail Malykh from RUDN University
IS IT GLUTEN FREE?
New modified wheat could help tackle global food shortage
Researchers at the University of York have created a new modified wheat variety that increases grain production by up to 12%.
Wheat is one of the most important food crops in the world, providing 20% of human calories; with ever increasing global food demand, increasing crop yield is critically important.
Wheat breeders work hard to increase yield to meet global demand, but since the 'green revolution' of the 1960s, the rate of yield increase has been slowing and is currently less than 1% per year.
Most improvements have been made by breeding varieties that produce higher numbers of grain, but it should also be possible to increase yield by producing plants with bigger grains. When this has been achieved, however, it is accompanied by a decrease in grain numbers.
Researchers at the University of York have now resolved this issue by directly modifying the growth of the young developing grain by increasing the amount of a protein that controls growth rates in plants.
This resulted in plants that produced grain that are up to 12% bigger than in the conventional variety. In field experiments conducted by their collaborators in Chile, they found that there was no decrease in grain number, resulting in an increase in yield.
Professor Simon McQueen-Mason, from the University of York's Centre for Novel Agricultural Products (CNAP) at the Department of Biology, said: "Experts predict that we need to increase global food production by 50% by 2030 in order to meet demand from population growth. The negative impacts of climate change on crop yields are making this even more challenging. While researchers are working hard to meet this challenge, there remains a lot to do."
"Attempts to increase the yield of wheat have been thwarted by the apparent trade-off between grain size and grain number. We decided to side-step this complex control system by giving a boost to the natural growth system that controls the size of plant tissues.
"We did this by increasing the levels of a protein called expansin, which is a major determinant of growth in plants. We targeted this modification so that it was confined to developing wheat grain, and are delighted by the results."
Research partners at the Universidad Austral de Chile conducted field experiments that demonstrated the effectiveness of the plants under agricultural conditions.
The team are now looking at ways to make this research accessible to farmers and the wider industry to help inform their decisions on crop production.
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The research, in collaboration with Professor Daniel Calderini in Chile and Dr Emma Wallington, at the National Institute of Agricultural Botany, was funded by the BBSRC in the UK and FONDECYT in Chile, and is published in New Phytologist.
In temperate trees, climate-driven increase in carbon capture causes autumn leaves to fall sooner
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE
For decades, scientists have expected that the shedding of leaves from temperate trees will get later and later under ongoing climate change. And early observations supported that idea, as warming caused leaves to stay on the trees later over recent decades, driving increased growing season length that could help to slow the rate of climate change. However, a large-scale study of European trees now suggests that this trend is beginning to change, and in fact, tree leaves may start to fall earlier as the productivity of those trees increases. The results build on growing evidence that plant growth is limited by the ability of tree tissues to use and store carbon. While changes in the growing-season lengths of temperate trees greatly affect global carbon balance, future growing-season trajectories remain highly uncertain because the environmental drivers of autumn leaf senescence are poorly understood. Autumn leaf-shedding at the end of the growing season in temperate regions is an adaptation to stressors, such as freezing temperatures. A common related assumption is that alleviating some of these stressors - as a warmer climate could - would allow leaves to persist longer to fix more atmospheric carbon by photosynthesis. However, the role of photosynthesis in governing the timing of leaf senescence has not been widely tested in trees. To do this, Deborah Zani and colleagues used long-term observations from dominant Central European tree species from 1948 to 2015, and experiments designed to modify carbon uptake by trees, to evaluate related impacts on senescence. Collectively, their data show that increased growing-season productivity in spring and summer due to elevated carbon dioxide, temperature, or light levels can lead to earlier - not later - leaf senescence. This is likely because roots and wood cease to use or store leaf-captured carbon at a point, making leaves costly to keep. The authors used their observations to build a model to improve autumn senescence prediction under a business-as-usual climate scenario. It forecasts the possibility of slight advances, not delays, in autumn leaf-dropping dates over the rest of the century. The results "substantially lower our expectations of the extent to which longer growing seasons will increase seasonal carbon uptake in forests," they write, though the universality of this pattern in other forest types remains unknown. They note an important next avenue of research is implementing such growing-season length constraints in Earth system and vegetation models, which currently do not consider these dynamics when predicting seasonal carbon dioxide uptake of plants. A related Perspective discusses the results in more detail.
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.
