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)
Thursday, August 12, 2021
The progress and promise of plant-made vaccines and therapeutics, including edible drugs
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)
Recent progress in developing and testing plant-made vaccines has revived interest in plant-produced pharmaceuticals, including edible drugs, for human use. Advances in technology and manufacturing could boost the uptake of therapeutics made in this way, say Hugues Fausther-Bovendo and Gary Kobinger in this Perspective. Therapeutic proteins such as antibodies, hormones, cytokines, and proteins in vaccines are generally produced in bacteria or eukaryotic systems, including chicken eggs and mammalian or insect cell cultures. In 1986, scientists proposed the use of plants for the production of these proteins; called “molecular farming,” this process can be less resource-intensive, less costly, and less likely to be a source of contaminants. So far, one plant-derived therapeutic protein for human use has been approved (in 2012, for Gaucher disease). In 2019, a plant-produced influenza virus vaccine completed phase 3 clinical trials with promising results, and in spring 2021, phase 3 trials for a plant-made vaccine against SARS-CoV-2 began. Fausther-Bovendo and Kobinger highlight several advantages that plant-produced proteins hold for vaccine development, in particular, citing the strong immune response the plant components of virus-like particles in vaccines can generate, which may reduce the need for adjuvants. Given orally, plant-made therapeutics are also interesting to consider, say Fausther-Bovendo and Kobinger; they might require minimal processing, thus possibly skipping expensive and time-consuming steps in the manufacturing process. Edible vaccines – still predominantly in the preclinical stage of development – are also currently under development, the authors note. Compared to proof-of-concept edible vaccines tested decades ago, which generated weak immune responses, new edible plant-made vaccines could now generate more powerful immune responses, thanks to improved technology. Because doses for therapeutics are much higher than for vaccines, investment in manufacturing infrastructure must increase to achieve large-scale manufacturing of plant therapeutic products, Fausther-Bovendo and Kobinger say.
JOURNAL
Science
DOI
10.1126/science.abf5375
ARTICLE TITLE
Plant-made vaccines and therapeutics
ARTICLE PUBLICATION DATE
13-Aug-2021
Palaeontology: Three fossils shed light on dinosaurs in China
Map showing the fossil site where the new sauropod dinosaur specimens were collected (A,B), and the relative positions of these three specimens (C).
Three dinosaurs from Northwest China represent two new species and are some of the first vertebrates uncovered in the region, according to a study published in Scientific Reports. The findings shed light on sauropods in China.
Dr. Xiaolin Wang and colleagues analysed fossil fragments (spinal vertebrae and rib cage) previously discovered in the Turpan-Hami Basin (Xinjiang, China) and dated to the Early Cretaceous (around 130 to 120 million years ago). They compared specific features of the remains (vertebrae and rib structure) to other sauropod dinosaurs from China and other localities.
The authors identified the first specimen as a new species and named it Silutitan sinensis. The authors found that some characteristics of the neck vertebrae indicate that it belonged to a family of sauropods known as Euhelopodidae, which so far have been found only in East Asia. They compared the specimen with what they believe was a closely related group of dinosaurs, or genus, (Euhelopus) and estimated that the specimen was originally over 20 metres long.
The authors named the second specimen, which they also identify as a new species, Hamititan xinjiangensis. The specimen consists of seven vertebrae from the tail, which the authors believe are the fourth to tenth in the spine. The authors conclude the shape and ridges along vertebrae suggest that it belonged to a family of sauropods known as Titanosaurs, abundant in both Asia and South America. They estimate the full specimen was 17 meters long by comparing it to what they believe to be closely related genera (Rapetosaurus and Opisthocoelicaudia).
The third specimen was limited to four vertebrae and rib fragments. The authors’ analysis suggests it may be a somphospondylan sauropod, a group of dinosaurs who lived from the late Jurassic, 160.3 million years ago to the late Cretaceous, 66 million years ago.
These samples are some of the first dinosaurs reported in the Turpan-Hami Basin, increasing the known diversity of the Mesozoic reptiles found in the area. The findings also shed light on which sauropods were present in China.
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Article details
The first dinosaurs from the Early Cretaceous Hami Pterosaur Fauna, China
Chestnut Hill, Mass. (08/12/2021) -- The world may need to start thinking differently about plants, according to a new report in the journal Science by researchers who took a fresh look at spore-like microfossils with characteristics that challenge our conventional understanding about the evolution of land plants.
Found in rock samples retrieved in Australia more than 60 years ago, the microfossils dating to the Lower Ordovician Period, approximately 480 million years ago, fill an approximately 25-million-year gap in knowledge by reconciling the molecular clock - or pace of evolution - with the fossil spore record - the physical evidence of early plant life gathered by scientists over the years.
This reconciliation supports an evolutionary-developmental model connecting plant origins to freshwater green algae, or charophyte algae, said Boston College paleobotanist Paul Strother, a co-author of the new report. The “evo-devo” model posits a more nuanced understanding of plant evolution over time, from simple cell division to initial embryonic stages, rather than large jumps from one species to another.
“We found a mix of fossils linking older, more problematic spore-like microfossils with younger spores that are clearly derived from land plants,” said Strother. “This helps to bring the fossil spore record into alignment with molecular clock dates if we consider the origin of land plants as a long-term process involving the evolution of embryonic development.”
The fossil record preserves direct evidence of the evolutionary assembly of the plant regulatory and developmental genome, Strother added. This process starts with the evolution of the plant spore and leads to the origin of plant tissues, organs, and eventually macroscopic, complete plants – perhaps somewhat akin to mosses living today.
“When we consider spores as an important component of the evolution of land plants, there is no longer a gap in the fossil record between molecular dating and fossil recovery,” Strother said. Absent that gap, “we have a much clearer picture of a whole new evolutionary step: from simple cellularity to complex multicellularity.”
As a result, researchers and the public may need to re-think how they view the origin of terrestrial plants -- that pivotal advance of life from water to land, said Strother.
“We need to move away from thinking of the origin of land plants as a singularity in time, and instead integrate the fossil record into an evo-devo model of genome assembly across millions of years during the Paleozoic Era - specifically between the Cambrian and Devonian divisions within that era,” Strother said. “This requires serious re-interpretation of problematic fossils that have previously been interpreted as fungi, not plants.”
Strother and co-author Clinton Foster, of the Australian National University, set out tosimply describe an assemblage of spore-like microfossils from a deposit dating to the Early Ordovician age - approximately 480 million years ago. This material fills in a gap of approximately 25 million years in the fossil spore record, linking well-accepted younger plant spores to older more problematic forms, said Strother.
Strother and Foster examined populations of fossil spores extracted from a rock core drilled in 1958 in northern Western Australia. These microfossils are composed of highly resistant organic compounds in their cell walls that can structurally survive burial and lithification. They were studied at Boston College, and at the ANU’s Research School of Earth Sciences, with standard optical light microscopy.
“We use fossil spores extracted from rock drill cores to construct an evolutionary history of plants going back in time to the very origin of plants from their algal ancestors,” said Strother. “We have independent age control on these rock samples, so we study evolution by looking at changes in the kinds of spores that occur over time.”
Molecular biologists also look at evolutionary history through time by using genes from living plants to estimate the timing of plant origins using “molecular clocks” -- a measurement of evolutionary divergence based on the average rate during which mutations accumulate in a species’ genome.
However, there are huge discrepancies, up to tens of millions of years, between direct fossil data and molecular clock dates, said Strother. In addition, there are similar time gaps between the oldest spores and when actual whole plants first occur.
These gaps resulted in hypotheses about a “missing fossil record” of the earliest land plants,” said Strother.
“Our work seeks to resolve some of these questions by integrating the fossil spore record into an evolutionary developmental model of plant origins from algal ancestors,” Strother said.
JOURNAL
Science
DOI
10.1126/science.abj2927
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
A fossil record of land plant origins from charophyte algae
ARTICLE PUBLICATION DATE
13-Aug-2021
Disclaimer: AAAS and Eure
People in the Philippines have the most Denisovan DNA
Researchers have known from several lines of evidence that the ancient hominins known as the Denisovans interbred with modern humans in the distant past. Now researchers reporting in the journal Current Biology on August 12 have discovered that the Philippine Negrito ethnic group known as the Ayta Magbukon have the highest level of Denisovan ancestry in the world. In fact, they carry considerably more Denisovan DNA than the Papuan Highlanders, who were previously known as the present-day population with the highest level of Denisovan ancestry.
“We made this observation despite the fact that Philippine Negritos were recently admixed with East Asian-related groups—who carry little Denisovan ancestry, and which consequently diluted their levels of Denisovan ancestry,” said Maximilian Larena (@maxlarena) of Uppsala University. “If we account for and masked away the East Asian-related ancestry in Philippine Negritos, their Denisovan ancestry can be up to 46 percent greater than that of Australians and Papuans.”
In the new study, Larena and colleagues, including Mattias Jakobsson, aimed to establish the demographic history of the Philippines. Through a partnership between Uppsala University of Sweden and the National Commission for Culture and the Arts of the Philippines (NCCA), aided by collaboration with indigenous cultural communities, local universities, local government units, non-governmental organizations, and/or regional offices of the National Commission for Indigenous Peoples, they analyzed about 2.3 million genotypes from 118 ethnic groups of the Philippines including diverse self-identified Negrito populations. The sample also included high-coverage genomes of AustraloPapuans and Ayta Magbukon Negritos.
The study shows that Ayta Magbukon possess the highest level of Denisovan ancestry in the world, consistent with an independent admixture event into Negritos from Denisovans. Together with the recent discovery of a small-bodied hominin, called Homo luzonensis, the data suggest that there were multiple archaic species that inhabited the Philippines prior to the arrival of modern humans, and that these archaic groups may have been genetically related.
Altogether, the researchers say that the findings unveil a complex intertwined history of modern and archaic humans in the Asia-Pacific region, where distinct Islander Denisovan populations differentially admixed with incoming Australasians across multiple locations and at various points in time.
“This admixture led to variable levels of Denisovan ancestry in the genomes of Philippine Negritos and Papuans,” Jakobsson said. “In Island Southeast Asia, Philippine Negritos later admixed with East Asian migrants who possess little Denisovan ancestry, which subsequently diluted their archaic ancestry. Some groups, though, such as the Ayta Magbukon, minimally admixed with the more recent incoming migrants. For this reason, the Ayta Magbukon retained most of their inherited archaic tracts and were left with the highest level of Denisovan ancestry in the world.”
“By sequencing more genomes in the future, we will have better resolution in addressing multiple questions, including how the inherited archaic tracts influenced our biology and how it contributed to our adaptation as a species,” Larena said.
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This work was supported by the Swedish Research Council and the Knut and Alice Wallenberg Foundation.
Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.
JOURNAL
Current Biology
DOI
10.1016/j.cub.2021.07.022
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Philippine Ayta possess the highest level of Denisovan ancestry in the world
ARTICLE PUBLICATION DATE
12-Aug-2021
Researchers identify new enzyme that infects plants - paving the way for potential disease prevention
By discovering previously unexplored ways in which crop pathogens break through plant cell walls, the scientists have opened up opportunities for developing effective disease control technologies.
The new research, published in Science, describes a family of enzymes found in a microorganism called Phytophthora infestans. The enzymes enable crop pathogens to degrade pectin - a key component of plant cell walls - thereby enabling the pathogens to break through the plant’s defences to infect the plant.
Led by biologists and chemists from the University of York, the international team of researchers discovered the new class of enzymes that attack pectin called LPMOs. The team also showed that disabling the gene that encodes this enzyme rendered the pathogen incapable of infecting the host.
P. infestans is known to cause potato late blight, a devastating plant disease that led to widespread starvation in Europe and more than a million deaths in Ireland in the 1840s, in what became known as ‘The Great Famine’. Plant infection continues to cause billions of dollars’ worth of damage to global crop production each year and continues to threaten world food security.
The identification of this new gene could open up new ways of protecting crops from this important group of pathogens.
Lead author on the report, Dr Federico Sabbadin, from the Biology Department’s Centre for Novel Agricultural Products (CNAP), at the University of York said: “These new enzymes appear to be important in all plant pathogenic oomycetes, and this discovery opens the way for potentially powerful strategies in crop protection”.
Professor Simon McQueen-Mason, also from CNAP, remarked that the work was “the result of interdisciplinary collaborations between biologists and chemists at York along with plant pathologists at the James Hutton Institute, and genomicists at CNRS, with invaluable molecular insights from Professor Neil Bruce (CNAP) and Professors Gideon Davies and Paul Walton in the Department of Chemistry at York.”
The research is part of the project New Enzymatic Virulence Factors in Phytophthora infestans, running from 2021 to 2025, and is supported with a £1m grant from the Biotechnology and Biological Sciences Research Council, part of UK Research and Innovation (UKRI).
JOURNAL
Science
DOI
10.1126/science.abj1342
METHOD OF RESEARCH
Systematic review
SUBJECT OF RESEARCH
Cells
ARTICLE TITLE
Secreted pectin monooxygenases drive plant infection by pathogenic oomycetes
ARTICLE PUBLICATION DATE
13-Aug-2021
COLLECTIVE ACTION
Research shows flocking birds, schooling fish, other collective movements can stabilize ecosystems
CORVALLIS, Ore. – In addition to being visually stunning, schools of herring, herds of wildebeest and countless other groups of organisms that act in concert can help complex ecosystems maintain their diversity and stability, new research by Oregon State University shows.
Published today in Nature Ecology and Evolution, the study demonstrates that when individuals band together to consume resources as a collective group, the surrounding ecosystem is prone to be more resilient and able to support a wider range of species.
The findings could be an important step toward understanding how living systems stay on an even keel; collective behavior is ubiquitous on the planet, playing a prominent role in everything from bacterial biofilms to human cities.
“These collectives show highly organized, large-scale patterns in behavior that emerge spontaneously from localized interactions among nearby individuals,” said Ben Dalziel of the OSU College of Science. “Our question was, what is the significance of collective behavior in ecosystems?”
Dalziel and colleagues found that there was an emergent social-ecological feedback between the size and structure of the collective groups and the level of resources in an ecosystem, and that this feedback buffered the system against crashing. The feedback dampened fluctuations in resource abundance and allowed more consumer species to persist using the same resource, instead of the stronger competitor pushing the weaker one to extinction.
Dalziel, a population biologist, led a collaboration that examined the ecological significance of collective behavior through the lens of two enduring ecological puzzles: the paradox of enrichment and the paradox of the plankton.
The paradox of enrichment is seen when, in a predator-prey model, an increase in available food for the prey results in the predator’s population growing unsustainably big and destabilizing. The paradox of the plankton refers to diverse ecological communities, such as different types of phytoplankton, persisting even though lots of similar species are vying for finite resources.
“It is not a given that complex ecosystems will be stable – if you just throw a bunch of species together in an environment, theory tells us the result will likely be ecosystem collapse,” Dalziel said. “That means real ecosystems must have some kind of special sauce that allows them to persist with a diverse array of species.”
It turns out that collective behavior – occurring among plants as well as microorganisms, animals and people – could be a potent ingredient of the sauce, the researchers found.
Dalziel and Mark Novak of the College of Science, plus James Watson of the Oregon State College of Earth, Ocean, and Atmospheric Sciences and Stephen Ellner of Cornell University, started with a standard model of a simple food web: two generic “consumers” feeding on a shared resource.
A battery of equations expresses the model’s multiple variables, such as consumer mortality rate and per-capita resource consumption, but in this version of the model, the consumers differ only in the efficiency with which they capture the resource.
“We constructed simulations in such a way that we could turn collective behavior on and off without changing anything else in the system,” Dalziel said. “What we found was that adding collective behavior was a game changer in the simulations – it stabilized ecosystems that ecological and evolutionary theory clearly say should not otherwise be stable.”
That was a piece of the knowledge puzzle that had been missing, he said, noting that much work had been done to understand how local individual behavior scales up to affect group-level behavior and how those groups process information, but not much about why collective behavior happens in the first place.
Dalziel calls the findings a “good news story” that contrasts the negative role collective dynamics can play.
“Amidst the challenges we face with the spread of misinformation online, which also involves collective dynamics, here is an example where collective behavior plays a fundamental role in supporting life,” he said. “And I also think it’s neat that such an aesthetically striking aspect of ecosystems – the flocks of birds etc. – could also play an important role in their stability and diversity.”
The National Science Foundation, DARPA, the National Institutes of Health and NASA supported this research.
IMAGE: TIBETAN WOLVES AT THE PADMAJA NAIDU HIMALAYAN ZOOLOGICAL PARK, DARJEELING. THEIR COAT COLOR IS SHADED YELLOW.view more
CREDIT: S. SHANKAR
The inheritance of several coat color patterns in dogs has been controversially debated for decades. Researchers including Tosso Leeb from the Institute of Genetics of the University of Bern have now finally been able to solve the puzzle. Not only did they clarify how the coat color patterns are genetically controlled, but the researchers also discovered that the light coat color in white arctic wolves and many modern dogs is due to a genetic variant originating in a species that went extinct a long time ago. The study has just been published in the scientific journal Nature Ecology and Evolution.
Two pigments and a "switch" for all coat colors
Wolves and dogs can make two different types of pigment, the black one, called eumelanin and the yellow, pheomelanin. A precisely regulated production of these two pigments at the right time and at the right place on the body gives rise to very different coat color patterns. Prior to the study, four different patterns had been recognized in dogs and several genetic variants had been theorized which cause these patterns. However, commercial genetic testing of these variants in many thousands of dogs yielded conflicting results, indicating that the existing knowledge on the inheritance of coat color patterns was incomplete and not entirely correct.
During the formation of coat color, the so-called agouti signaling protein represents the body's main switch for the production of yellow pheomelanin. If the agouti signaling protein is present, the pigment producing cells will synthesize yellow pheomelanin. If no agouti signaling protein is present, black eumelanin will be formed. "We realized early on that the causative genetic variants have to be regulatory variants which modulate the rate of protein production and lead to higher or lower amounts of agouti signal protein", Tosso Leeb explains.
CAPTION
Five different color patterns in dogs controlled by promoter variants at the gene for agouti signaling protein. The activity of the ventral promoter (VP) or the hair cycle specific promoter (HP) is schematically indicated under each dog.
CREDIT
NEE / Tosso Leeb
Five instead of four distinct coat color patterns
The gene for agouti signaling protein has several initiation sites for reading the genetic information, which are called promoters. Dogs, on the one hand, have a ventral promoter, which is responsible for the production of agouti signaling protein at the belly. On the other hand, dogs have an additional hair cycle-specific promoter that mediates the production of agouti signaling protein during specific stages of hair growth and enables the formation of banded hair.
For the first time, the researchers characterized these two promoters in detail, in hundreds of dogs. They discovered two variants of the ventral promoter. One of the variants conveys the production of normal amounts of agouti signaling protein. The other variant has higher activity and causes the production of an increased amount of agouti signaling protein. The researchers even identified three different variants of the hair cycle-specific promoter. Starting with these variants at the individual promoters, the researchers identified a total of five different combinations, which cause different coat color patterns in dogs. "The textbooks have to be rewritten as there are five instead of the previously accepted four different patterns in dogs", Leeb says.
CAPTION
Arctic Wolf (Canis lupus arctos) in the Lüneburg Heath wildlife park, Germany. The white coat color is caused by the same genetic variant that leads to the dominant yellow color in dogs.
CREDIT
Quartl
Unexpected insights on the evolution of wolves
As many genomes from wolves of different regions on earth have become publicly available, the researchers further investigated whether the identified genetic variants also exist in wolves. These analyses demonstrated that the variants for overactive ventral and hair cycle-specific promoters were already present in wolves prior to the domestication of modern dogs, which started approximately 40,000 years ago. Most likely, these genetic variants facilitated adaptation of wolves with a lighter coat color to snow-rich environments during past ice ages. Today, the completely white arctic wolves and the light colored wolves in the Himalaya still carry these genetic variants.
Further comparisons of the gene sequences with other species of the canidae family yielded very surprising results. The researchers were able to show that the overactive variant of the hair cycle-specific promoter in light-colored dogs and wolves shared more similarities with very distantly related species such as the golden jackal or the coyote than with the European grey wolf.
"The only plausible explanation for this unexpected finding is an ancient origin of this variant, more than two million years ago, in a now extinct relative of wolves", Leeb says. The gene segment must have been introgressed more than two million years ago into wolves by hybridization events with this now extinct relative of wolves. Thus, a small piece of DNA from this extinct species is still found today in yellow dogs and white arctic wolves. "This is reminiscent of the spectacular finding that modern humans carry a small proportion of DNA in their genomes from the now extinct Neandertals", Leeb adds.
CAPTION
Eurasian grey wolf at Polar Zoo in Bardu, Norway, with the coat color agouti.
CREDIT
Mas3cf
International collaboration was key to success
The study was enabled by a sabbatical done by Prof. Danika Bannasch at the University of Bern with its longstanding research focus on the genetics of coat color in domestic animals. Bannasch, a professor in veterinary genetics at the University of California Davis, filtered the relevant promoter variants from thousands of other functionally neutral genetic variants. The evolutionary analyses were conducted by Christopher Kaelin und Gregory Barsh of the HudsonAlpha Institute and Standford University.
JOURNAL
Nature Ecology & Evolution
DOI
10.1038/s41559-021-01524-x
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Dog colour patterns explained by modular promoters of ancient canid origin
ARTICLE PUBLICATION DATE
11-Aug-2021
Tree falls during dry season in São Paulo City are due to poor management, study suggests
An article in Trees - Structure and Function reports findings from an analysis of 7,000 tree falls in a three-year period. Stormy weather was the main cause during the rainy season.
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO
IMAGE: STORMY WEATHER WAS THE MAIN CAUSE DURING THE RAINY SEASONview more
CREDIT: PRISCILLA CERQUEIRA
Trees fall every day in São Paulo, Brazil, the largest and most populous city in Latin America, but most tree falls occur in the rainy season owing mainly to the effects of temperature, strong winds and heavy rain. When trees fall in the dry season, the main direct cause is not weather but a lack of management and adequate conditions for the survival of street vegetation.
These are the key findings of a study published by a group of Brazilian researchers in the journal Trees - Structure and Function as part of its “Urban Trees” collection. The study was supported by FAPESP via two projects (19/08783-0 and 20/09251-0).
The scientists analyzed daily tree fall data and identified some 7,000 occurrences in three years. São Paulo lost 1% of its street trees in the period, for an average of 6.2 falls per day. The worst day was December 29, 2014, when 337 tree falls were reported in 24 hours. Ibirapuera Park, the city’s largest green area, had to be closed because of the number of trees blown down in the storm.
Trees are considered crucial to maintaining or improving environmental quality in cities. They play an important role in carbon storage and uptake, helping mitigate the adverse effects of global warming and pollution. They also help reduce flooding by increasing the more permeable soil area and reducing the speed and volume of stormwater runoff by intercepting part of the rain.
“Out of São Paulo’s 652,000 street trees, 7,034 fell in the period 2013-16. Our analysis showed that tree fall is driven by precipitation, wind gust and temperature during the wet season. While temperature directly influences tree fall, both precipitation and wind gust may have lagged effects, leading to tree fall some days after the weather event. However, such associations with climate were not observed during the dry season, although trees fell on two-thirds of the days in the season, confirming problems due to poor stewardship and conditions,” the article can be summarized as concluding.
The data used in the study came from the City of São Paulo’s Center for Emergency Management. The exact location of each tree fall was not available. The researchers focused on correlations between daily weather and tree falls, estimating immediate effects and the impact of rain and wind a few days after a storm.
“When rainfall is heavy, trees retain much more water and their weight increases. In addition, large amounts of water in the ground reduce soil-root friction, making a fall more likely. If the soil is waterlogged, however, the increase in soil weight offsets the loss of friction, and the tree may not fall during heavy rain. As the soil dries out, its weight decreases without any increase in friction, and it may fall,” Giuliano Locosselli, a researcher at IB-USP’s Department of Botany and first author of the article, told Agência FAPESP.
The co-authors included Marcos Silveira Buckeridge, a professor at the University of São Paulo’s Institute of Biosciences (IB-USP), and Priscilla Cerqueira, an agricultural engineer and head of the Urban Tree Division of the City of São Paulo’s Department of the Environment.
According to Locosselli, the results show that the effects of climate are concentrated in the rainy season. “Trees fall apparently without climate-related causes during the dry season, evidencing lack of care and structural problems that have been occurring for some time,” he said.
For example, trees are pruned incorrectly, weakening their structure or balance, sidewalks strangle their roots or hinder their development, and there is often insufficient room for them to grow.
“Poorly managed trees are likely to fall even without apparent climate-related causes. Senescent vegetation can fall owing to impairment of photosynthesis, root support, growth and resistance to pathogens, which take advantage of the urban climate to reproduce and develop. It’s not unusual to find trees in poor conditions that can fall for no apparent reason,” Locosselli said.
For Cerqueira, evidencing the lagging effects of rain and wind as causes of tree falls is one of the most significant aspects of the study. “Front-line municipal workers see what’s happening day to day, and know tree falls are reported all year long, but we used the dry season as a baseline,” she said. “The lagging effects of weather are important. Now we need to think about the action that should be taken immediately after stormy rain and wind to minimize the risk of tree falls, and to be ready to act if they happen.”
The researchers did not analyze the direct impact of age or pollution on tree health, but Locosselli said the fact that a large number of São Paulo’s trees were planted in the 1950s and 1960s contributes to their vulnerability and likelihood of falling.
With regard to air pollution, an article published in 2019 and co-authored by Locosselli showed that atmospheric pollutants stunt the growth of tipuana trees (Tipuana tipu), which are among the most common tree species in the city, and impair the ecosystem services they provide (more at: agencia.fapesp.br/30552).
Suggestions
Among the actions required to protect street trees in São Paulo, according to the study, are management and planning that takes into account species biology, resilience to extreme weather, and the characteristics of the local infrastructure.
The authors also recommend the implementation of tree monitoring programs using tree health indicators, and educational campaigns to win public support for science-based government decisions.
The City of São Paulo is legally responsible for managing street trees (Municipal Law 10,365/87). This includes planting, protecting tree health, pruning, and replacing trees when necessary. The actual work is outsourced to contractors. The electric power utility is allowed to trim tree crowns to make way for overhead power cables.
According to Cerqueira, a 20-year Municipal Urban Tree Plan was implemented in September 2020, aiming at planning and management to enhance resilience of the city to climate change, provision of shade and aesthetic benefits, and “satisfaction of the public”.
“Several aspects of tree management and planting highlighted in the study match the problems diagnosed by the Municipal Plan, which details programs and actions to address each problem,” she said.
The Plan is due for a review in 2025. For this first five-year period it sets priorities such as producing a fall risk analysis protocol and an emergency management project that includes an audit of the agreements signed with contractors and the utility in an effort to reduce the amount of pruning and damage to trees.
“The general public is more aware of the importance of trees. Popular participation has increased. When a tree falls, especially after a storm, we get many more calls. We plan to improve the technical material addressed to the public,” Cerqueira said.
With more than 12 million inhabitants, São Paulo has an area of 1,521 square kilometers and a subtropical climate. Roughly 75% of its streets have trees of various native species, including some from the Atlantic Rainforest, as well as exotic species, but most are in more central districts of the city. Planting more trees in outlying neighborhoods is one of the aims of the Municipal Plan.
Next steps
Locosselli said he has embarked on a new study with Cerqueira and other colleagues, analyzing georeferenced data available since 2012 for 30,000 trees in the city. “We’re looking at where trees are located to understand how tree falls are influenced by the surroundings and the environment. The study encompasses 19 variables, such as pollution, sidewalk width and slope, climate, and building height. We should be finished well before the end of the year,” he explained.
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About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at http://www.fapesp.br/en and visit FAPESP news agency at http://www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
JOURNAL
Trees
DOI
10.1007/s00468-021-02145-4
METHOD OF RESEARCH
Case study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Climate drivers of tree fall on the streets of São Paulo, Brazil
