In 2023, after years of pollution, equipment failures, and health concerns, the Cumberland Fossil Plant in Tennessee was slated to close within the decade.

The coal-fired plant had been part of a multibillion-dollar settlement in 2011 after its operator, the Tennessee Valley Authority, failed to install pollution control technology a decade earlier. Regulators cited the plant for more air-pollution violations in 2017 and 2023. TVA said it would shutter Cumberland’s units in 2026 and 2028.

Then the Trump administration replaced four of TVA’s board members, and the agency reneged on its retirement plan in February. Now, TVA has a federal pledge for $46 million to extend Cumberland’s lifespan—part of a nationwide push by President Donald Trump to keep older coal plants running.

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In a groundbreaking revelation that could reshape our understanding of plant-microbe interactions and agricultural biotechnology, researchers have unveiled a novel chemical communication mechanism between rice roots and beneficial soil bacteria. This newly discovered pathway centers on the secretion of heptadecanoic acid, a specific fatty acid, which effectively recruits Bacillus species to the rhizosphere, the densely populated soil region surrounding plant roots. Such a mechanism not only highlights the intricate biochemical dialogues that underpin plant-microbe symbioses but also opens promising avenues for sustainable crop management through microbiome engineering.

Rice, a staple food that sustains more than half of the world’s population, has long been studied for its interactions with the soil ecosystem. The rhizosphere harbors myriad microbial communities, some of which promote plant health by enhancing nutrient acquisition, defending against pathogens, or improving stress tolerance. Identifying the exact signals that facilitate recruitment of beneficial bacteria has presented a considerable scientific challenge. The recent study by Zeng, Wen, Zhao, and colleagues provides essential insights and fills a critical gap by pinpointing heptadecanoic acid as a chemical attractant secreted by rice roots, which acts as a molecular beacon for Bacillus.

Heptadecanoic acid, also known as margaric acid, is a saturated fatty acid containing 17 carbon atoms. Traditionally, plant root exudates—complex mixtures of organic acids, sugars, amino acids, and secondary metabolites—have been observed to influence microbial colonization, but the specific involvement of fatty acids as signals was less appreciated. The team’s meticulous biochemical analyses have now elucidated that rice roots not only exude heptadecanoic acid but do so strategically when recruiting beneficial Bacillus species. This revelation signifies a refined understanding of the selective microbial recruitment strategies employed by plants.

The team’s research employed an array of advanced techniques—ranging from root exudate profiling through gas chromatography-mass spectrometry (GC-MS) to microbial chemotaxis assays—to validate that Bacillus species detect and are attracted to gradients of heptadecanoic acid in the rhizosphere. Importantly, not all soil microbes respond equivalently, underscoring the specificity of this fatty acid signal. Functional studies further demonstrated that disrupting rice root production of heptadecanoic acid diminished Bacillus colonization, which correspondingly weakened the plant’s resistance to common soil-borne pathogens.

Understanding the biochemical basis for such recruitment enables scientists to rethink approaches to crop protection and enhancement. Bacillus species are well-known for their plant growth-promoting traits, including production of antimicrobial compounds, enhancement of nutrient solubilization, and induction of systemic resistance in plants. By harnessing the heptadecanoic acid signaling pathway, it is conceivable that agricultural inoculants could be optimized to improve colonization efficiency and consistency in field conditions, potentially reducing the need for chemical pesticides and fertilizers.

This molecular dialogue highlights a sophisticated communication network where plants actively shape their microbial environment. The discovery that a fatty acid functions not merely as a structural or energy-storage molecule but as a signaling compound redefines our conception of root exudate complexity. Moreover, heptadecanoic acid’s hydrophobic nature prompts questions about its diffusion dynamics in soil and the mechanisms by which Bacillus receptors detect it. Future exploration into bacterial chemoreceptors and downstream signaling pathways activated by this molecule could illuminate novel targets for microbiome manipulation.

Beyond direct agricultural implications, this finding resonates with broader ecological principles. The soil microbiome’s composition significantly influences plant community dynamics, ecosystem productivity, and resilience to environmental stresses. By uncovering a precise mediator of microbe recruitment, the work by Zeng and colleagues contributes to the fundamental ecological theory of plant-soil feedback loops, suggesting that plants possess active biochemical agency in curating their microbial consortia.

Interestingly, the secretion of heptadecanoic acid is not constant but modulated by environmental cues and plant developmental stages, emphasizing the dynamic nature of root exudation profiles. This temporal regulation indicates that plants might selectively recruit beneficial microbes in response to specific physiological needs or external threats, adding an adaptive dimension to this interaction. Understanding these controls could inform timing strategies for microbial inoculant application in agriculture to coincide with natural recruitment periods.

The authors also raise intriguing evolutionary considerations. The conserved ability among rice varieties to secrete heptadecanoic acid suggests selective pressure favoring plants capable of enlisting Bacillus partners. Parallel studies on other cereal crops could reveal whether this fatty acid signaling is a widespread mechanism or unique to rice. Such comparative analyses across plant taxa may unearth a broader family of fatty acid signals mediating symbioses and expand the toolkit for synthetic microbiome engineering.

This pioneering investigation underscores the necessity of interdisciplinary approaches combining plant biology, microbiology, analytical chemistry, and ecology to fully decipher plant-microbe interactions. It leverages cutting-edge omics technologies and bioinformatics pipelines to characterize metabolite profiles and microbial responses, illustrating the power of integrative science. The robust experimental design and reproducible methodologies set a new benchmark for future studies aiming to parse root exudate signaling.

As the global agricultural sector grapples with the challenges of increasing food production sustainably on finite arable land under climate change pressures, the discovery of a natural plant mechanism to recruit growth-promoting and protective microbes represents a potentially transformative tool. Strategies informed by such foundational knowledge could reduce reliance on synthetic inputs, lower environmental footprints, and enhance crop resilience, aligning with ambitious global sustainability goals.

In conclusion, the identification of heptadecanoic acid as a pivotal signaling molecule secreted by rice roots to attract beneficial Bacillus species marks an exciting advance in the field of plant-microbe research. It unravels a previously unrecognized layer of biochemical communication with profound implications for agriculture and ecology. Continued investigation into the molecular details, environmental regulation, and cross-species relevance of this signaling mechanism promises to unlock innovative avenues for crop improvement and sustainable farming practices worldwide.

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Subject of Research: Plant-microbe interactions focusing on the biochemical signaling between rice roots and Bacillus species mediated by heptadecanoic acid secretion.

Article Title: Author Correction: Rice roots recruit Bacillus via the secretion of heptadecanoic acid.

Article References: Zeng, J., Wen, T., Zhao, J. et al. Author Correction: Rice roots recruit Bacillus via the secretion of heptadecanoic acid. Nat. Plants (2026). https://doi.org/10.1038/s41477-026-02341-5

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Scientists Warn: Eastern and Southern Asian Gymnosperms Face Imminent Extinction Amid Accelerating Climate Change

The botanical world stands on the edge of a crisis as groundbreaking research exposes the severe vulnerability of gymnosperms inhabiting Eastern and Southern Asia. A study published recently in Communications Earth & Environment projects a grim future for these ancient plant species, contriving to predict their potential extinction driven by rapid, anthropogenic climate shifts. Gymnosperms, a critical group of seed-producing plants including pines, cycads, and ginkgos, have thrived on Earth for millions of years, yet they now face an unprecedented existential threat.

The research team, led by environmental scientists Tang C.Q., Matsui T., and Shitara T., delved deep into the combined effects of rising temperature, shifting precipitation patterns, and increased frequency of extreme weather events on gymnosperm populations. Their models integrate climate projections with species-distribution data, revealing that the traditionally temperate and subtropical niches occupied by these gymnosperms will dramatically shrink by the middle of the 21st century. The researchers underscored that this decline is not uniform; rather, certain species endemic to specific mountainous or coastal ecosystems display alarmingly higher risk profiles.

Gymnosperms perform indispensable ecological functions, including carbon sequestration, habitat provision, and soil stabilization. Their dwindling numbers could initiate cascading environmental consequences in Asia’s biodiverse forests. The botanical group’s deep-rooted historical presence has allowed ecosystems to flourish through millennia; however, current climate trends disrupt the intricate balance of these habitats at a speed too fast for evolutionary adaptation or migration to compensate.

The research methodology involved coupling high-resolution climate modeling with phylogenetic analysis of gymnosperms. By mapping physiological tolerances and reproductive traits against future climate scenarios simulated under various Representative Concentration Pathways (RCPs), the study offers one of the most comprehensive assessments to date. Crucially, it highlights that while some gymnosperm species maintain a degree of resilience due to wider ecological amplitude, many are specialists confined to narrow environmental parameters and thereby disproportionately susceptible.

Tang and colleagues emphasize the intricate relationship between temperature increases and drought incidence in the region, noting that these stressors synergistically impair gymnosperm vitality. Water stress impacts photosynthetic efficiency, disrupts nutrient uptake, and elevates susceptibility to pests and diseases. In marginalized microhabitats or high-altitude refugia, these effects intensify, leading to localized extirpations that can spiral into broader population collapses over time.

The implications extend beyond botanical loss; gymnosperms constitute foundational species in many forest ecosystems, affiliate with mycorrhizal fungi essential for nutrient cycling, and provide resources for myriad animal taxa. The potential disappearance of these plants risks triggering ethological and trophic-level shifts, reducing ecosystem resilience to further climate perturbations. Furthermore, economically important species used for timber, traditional medicine, and cultural practices face sharp declines, posing socioeconomic challenges.

This research also serves as a dire warning against complacency in regional conservation strategies. Protected areas alone may prove insufficient if climatic envelopes shift beyond the reach of current reserves. The scientists advocate for integrated approaches, including assisted migration, ex situ conservation, and the establishment of ecological corridors to facilitate natural dispersal. Prioritizing gymnosperms with limited dispersal ability and narrow ecological niches is urgent to formulate responsive management frameworks.

The study explores the genetic diversity patterns across gymnosperm populations to evaluate adaptive capacity. Low genetic variability combined with rapid environmental changes diminishes resilience, constraining evolutionary potential. Loss of phylogenetic diversity risks undermining ecosystem functions more severely than numerical species losses alone, as more distinct lineages harbor unique functional traits critical for ecosystem stability.

Researchers also discuss phenotype plasticity and reproductive timing alterations in response to shifting climate variables. Disruptions in phenology—such as mismatches in pollination timing or seed maturation cycles—further complicate species survival trajectories. These dynamics, observed empirically in several regional species, underscore the complex interplay of biotic responses to multifaceted climate stressors.

The comprehensive data synthesis provided by Tang et al. highlights key geographic hotspots where gymnosperm extinction risk concentrates. Mountain ranges and isolated forest patches in Eastern China, Vietnam, and parts of the Himalayas emerge as critical areas for intensified conservation actions. In contrast, some upland refuges might preserve pockets of gymnosperm diversity, warranting prioritized protection and monitoring.

The projected losses loom as one of the most significant biodiversity crises in plant history within this region. The consequences for carbon dynamics depend on how these gymnosperm populations, which often function as carbon reservoirs, respond to climate change. The decline of such reservoirs exacerbates atmospheric CO2 accumulation, amplifying global warming in a feedback loop.

This study further calls for robust interdisciplinary collaboration between climatologists, ecologists, foresters, and policymakers to devise adaptive strategies addressing these challenges. Integrating remote sensing, long-term ecological monitoring, and community-based conservation initiatives could bolster efforts to safeguard remaining gymnosperm populations.

In conclusion, this sobering new evidence underscores the urgent need for both mitigating climate change drivers and innovating species-specific conservation measures. By illuminating the precarious status of Eastern and Southern Asian gymnosperms, Tang and colleagues have provided an essential scientific foundation that demands immediate international attention and action. Failing to act risks erasing a vital part of Earth’s botanical heritage, with irreversible ramifications for ecosystems and human societies alike.

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Subject of Research: Extinction risk of Eastern and Southern Asian gymnosperms under climate change.

Article Title: Eastern and southern Asian gymnosperms are doomed to extinction under climate change.

Article References:
Tang, C.Q., Matsui, T., Shitara, T. et al. Eastern and southern Asian gymnosperms are doomed to extinction under climate change. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03759-7

Image Credits: AI Generated

Dogs may have more in common with humans than just sharing our homes and routines. A new study has found that the same biological signals linked to lifespan in people also appear in dogs, suggesting that both species may age in remarkably similar ways. The research comes from the Dog Aging Project, a long-term study […]

The post Dogs and humans age in similar ways, surprising study finds appeared first on Knowridge Science Report.

In a groundbreaking advancement that could reshape the landscape of bioelectronic medicine, researchers have developed a wirelessly powered, bioresorbable electrical stimulation system with unprecedented programmable control over stimulation waveforms. This innovation integrates tissue-penetrating near-infrared (NIR) light to modulate electrical currents with precision, harnessing a novel bioresorbable silicon phototransistor as the cornerstone of its operation. Pioneering beyond earlier monophasic pulse devices, this technology allows for the delivery of monophasic, biphasic, and polyphasic stimulation patterns, significantly enhancing the versatility and therapeutic potential of implantable electrical stimulators designed to dissolve harmlessly after use.

Traditional electrical stimulators implanted in biological tissues have largely relied on wired connections or bulky batteries, impeding patient mobility and often necessitating additional surgeries for device removal. Bioresorbable devices emerged as a solution to these challenges by safely degrading in the body over time, eliminating the risks associated with permanent implants. However, these earlier systems primarily delivered monophasic pulses, limiting therapeutic precision and adaptability in complex treatments. The innovation reported by Kim, Seo, Wang, and colleagues introduces a new paradigm by integrating wireless power transfer via NIR light and programmable waveform control within a fully bioresorbable platform, thus extending the functional range and easing the clinical management of bioelectronic therapies.

Central to this system is the incorporation of bioresorbable silicon phototransistors engineered to serve as optoelectronic modulators within the electrical circuitry. When illuminated by externally applied near-infrared light that penetrates deep into biological tissues, these phototransistors effectively adjust current flows at critical circuit nodes. This optical modulation capability replaces conventional electronic control elements, which often rely on persistent power sources or invasive wiring, thereby enabling the device to operate autonomously while still allowing fine-tuning of stimulation parameters through non-contact optical inputs.

The adoption of near-infrared light as the wireless power and control mechanism is particularly significant. NIR light possesses the ability to penetrate through several centimeters of tissue without causing damage, providing a safe and efficient transmission channel between the external controller and the implanted device. This feature supports programmability in situ, empowering clinicians to tailor electrical stimulation waveforms dynamically after device implantation. Precisely controlling the shape, amplitude, and timing of the electrical pulses is crucial for optimizing therapeutic outcomes in applications such as neuroregeneration and cardiac pacing.

The research team demonstrated the remarkable versatility of their bioresorbable system by successfully delivering a variety of stimulation waveforms. Monophasic pulses, which are unidirectional current flows, serve as a baseline therapy. More complex biphasic and polyphasic waveforms, which alternate current direction and comprise multiple phases respectively, have been shown to minimize tissue damage and improve efficacy in various biosignaling contexts. The ability to generate these sophisticated patterns expands the therapeutic range of the device, potentially enabling treatments that were previously inaccessible using bioresorbable technologies.

In demonstrating practical utility, the device was tested in both small and large animal models, validating its capacity for clinically relevant electrical stimulation regimes. The system was effectively employed in single- and dual-chamber cardiac pacing, a critical intervention for managing arrhythmias and heart block. Through controlled electrical stimulation, the device could synchronize cardiac contractions, a feat crucial for restoring efficient cardiac output. These trials highlight the translational potential of the technology for future human applications, situating it as a promising alternative to current electronic pacemakers that require permanent implantation and battery replacements.

Further extending the functional scope, the researchers utilized the bioresorbable stimulator to activate phrenic neuromuscular pathways to either induce or block diaphragmatic movements. The phrenic nerve controls diaphragmatic excursion, essential for respiration, and its modulation has significant implications for respiratory therapies, such as in patients with spinal cord injuries or central hypoventilation syndromes. By enabling wireless, programmable neurostimulation of the phrenic nerve, the technology offers a minimally invasive approach to manage life-sustaining respiratory functions, with the added benefit of device degradation after the therapeutic window.

The bioresorbable nature of the silicon phototransistors and associated electronics assures that after fulfilling their therapeutic role, the devices gradually dissolve into biocompatible byproducts. This process circumvents the complications related to device explantation surgeries, reducing patient risk and healthcare costs. Moreover, the materials chosen minimize inflammatory responses and tissue irritation, facilitating seamless integration with host biology during the operational phase.

The engineering behind this system represents an intersection of materials science, optoelectronics, and biomedical engineering. The architecture leverages the semiconducting properties of silicon in thin-film, bioresorbable form, combined with circuit design optimized for minimal power consumption and maximal efficiency during NIR irradiation. These multidisciplinary innovations collectively overcome longstanding barriers in the fabrication of transient electronic implants capable of sophisticated programmable functionality.

Controlling the stimulation waveforms via light permits remote adjustment without physical connections, paving the way for real-time therapeutic modulation responsive to patient status or physiological signals. Future iterations could incorporate feedback mechanisms by integrating bioresorbable sensors that monitor tissue response, creating closed-loop systems for personalized medicine. This dynamic adaptability could be transformative in managing chronic conditions requiring variable and responsive electrical stimulation protocols.

This research also addresses one of the fundamental challenges of implantable devices: power delivery. The optical wireless power transfer circumvents the need for bulky batteries or explant procedures, offering renewed device miniaturization potential. Coupled with programmable phototransistors, these innovations enable multifunctional implants that conform to soft tissues and degrade harmlessly, a trifecta crucial for implantation in sensitive organs like the heart and nervous system.

The ability to deliver polyphasic waveforms through a single bioresorbable receiver unit is particularly noteworthy. Conventionally, generating these complex waveforms requires sophisticated circuitry and stable power sources, neither of which are trivial to implement in resorbable devices. The research showcases how optical control unlocks this capability without sacrificing bioresorbability or wireless operation, representing a paradigm shift in transient biomedical electronics.

The successful application of this device in large animal cardiac models bridges a critical gap toward clinical translation. Such models replicate human physiological scales and complexities far more closely than small animals, validating both the efficacy and safety of the system under conditions analogous to human therapies. This demonstration is an essential milestone on the path toward human clinical trials and eventual regulatory approval.

Moreover, the phrenic nerve stimulation experiments illustrate the broader applicability beyond cardiac pacing. Neuromuscular control via electrical stimulation has vast clinical relevance, from restoring motor function to modulating organ systems. The biodegradable, wireless nature of this system makes it especially suited for temporary therapeutic interventions, such as post-surgical recovery or transient disease states, where permanent implants would be unnecessary or undesirable.

While this work represents a major leap forward, ongoing challenges remain, including further optimization of device longevity relative to treatment durations, refinement of light delivery systems to maximize tissue penetration and minimize off-target effects, and integration with advanced biocompatible materials to tailor resorption timelines. Addressing these will be key to broadening the range of clinical applications and ensuring patient safety across diverse scenarios.

Overall, this wirelessly powered, light-controlled, bioresorbable stimulation system emerges as a versatile platform poised to transform bioelectronic therapies. Its elegant combination of programmable polyphasic waveform delivery, wireless operation via near-infrared light, and full bioresorbability addresses critical limitations of current implantable stimulators. By enabling sophisticated, minimally invasive, and transient electrical stimulation paradigms, this technology advances the frontiers of regenerative medicine, cardiac therapy, and neuromodulation, marking a significant milestone in the evolution of biomedical devices.

Subject of Research: Wireless bioresorbable electrical stimulation device with programmable waveform control using near-infrared light

Article Title: A wirelessly powered, light-controlled, bioresorbable stimulation system with programmable polyphasic waveforms

Article References:
Kim, J.U., Seo, S.G., Wang, H. et al. A wirelessly powered, light-controlled, bioresorbable stimulation system with programmable polyphasic waveforms. Nat Electron (2026). https://doi.org/10.1038/s41928-026-01655-8

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41928-026-01655-8

Tiny water-secreting pores appear to organize the major veins of the plant leaves into an arrangement known as a Voronoi diagram.

When a whale dies, a very special natural phenomenon can come alive. The carcass might float at the surface for some time, attracting sharks and other predators. As it becomes weathered, it may start to sink, falling through the water until it eventually settles on the seafloor, where deep-sea scavengers feast upon it. The scientific […]

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The first global map of subterranean fungi networks reveals how massive its reach is worldwide.

With machine learning and a high-resolution imaging robot, scientists measured and mapped the extent of Earth’s carbon circulatory system.

The pharmaceutical cabinet of the future might look a lot like a garden.

Rice is one of the world’s most important foods, providing a daily source of calories for nearly half of the global population. It is also an important source of magnesium, a mineral that helps support healthy muscles, nerves, bones, and energy production in the human body. Scientists have long known that magnesium plays an important […]

The post Scientists discover a key protein that makes rice more nutritious and tastier appeared first on Knowridge Science Report.

Silphium was an extinct Libyan plant renowned for contraception, medicine, and trade. Its disappearance remains a historical mystery, and scientists continue searching for surviving descendants. Roman leader Julius Caesar is said to have kept a stock of it in the treasury. Ancient writer Pliny the Elder says Rome’s Emperor Nero owned the last stalk of [...]

Researchers have uncovered why a common and costly dental implant infection often resists antibiotics. Dental implants have helped tens of millions of people regain a full set of stable, functional teeth, something traditional dentures cannot provide. However, between 10% and 20% of implant recipients eventually develop peri-implantitis, a serious infection that damages the jawbone around [...]

Light pollution prompts plants to shed pollen longer and stronger, according to new research.

© Amir Hamja for The New York Times

Light pollution prompts plants to shed pollen longer and stronger, according to new research.

For decades, scientists have understood that plants can release volatile organic compounds—essentially airborne chemical signals—to attract the natural enemies of the things that eat them, like caterpillars. What we didn’t know was exactly how a plant translates the physical act of being eaten into a specific, predator-summoning distress signal.

“[One] thing we didn’t know is how the plant detects the caterpillar in the first place,” says Adam Steinbrenner, a biologist at the University of Washington. Now, after years of experimenting with common bean plants in the lab and in the agricultural fields of Oaxaca, Mexico, Steinbrenner’s team pinpointed a single immune receptor that orchestrates its anti-caterpillar defense system.

Drooling caterpillars

When an herbivorous insect like a caterpillar feeds on a plant, it introduces its saliva straight into the plant's damaged tissues. This saliva contains biological clues called HAMPs: herbivore-associated molecular patterns. One of the HAMPs molecules is a peptide called inceptin, and there’s an 11-amino acid fragment of inceptin named In11, as well. Both of them turn out to be a fragment of the ATP synthase found in chloroplasts—basically a piece of one of the plant’s own proteins. As the caterpillar ingests the leaf, its gut enzymes chop up the plant's cellular engines and their pieces, including In11, are regurgitated back onto the leaf’s surface, albeit at extremely small concentrations.

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Researchers from Okinawa Institute of Science and Technology and Japan Agency for Marine-Earth Science and Technology have identified how bacteria can adapt to toxic metals released from hydrothermal vents. The study focused on Nitratiruptor sp. SB155-2, a species of bacteria isolated from vents in the Okinawa Trough. The researchers found that bacteria use transporter proteins […]

The post Testing their mettle: How bacteria in deep-sea vents deal with toxic metal environments appeared first on Science Bulletin.

Superbloom (noun, SOO-per-bloom)

Superblooms are massive blooms of desert wildflowers. There isn’t an exact number of flowers required to make something a superbloom. But the word usually describes an above-average number of blossoms. These flowers create colorful carpets that blanket usually barren desert landscapes. They can even be seen from space!

Deserts are dry ecosystems that get less than 25 centimeters (10 inches) of precipitation a year. As a result, these environments often have very little plant life.

The few flowering plants that do grow in deserts live very short lives. They spring up after rainfalls and race through their life cycles in a few days or weeks before heat and drought wipe them out. Before they die, these plants produce lots of seeds. Those seeds can lie dormant in the soil for years or even decades, waiting for the right conditions to sprout.

This creates a buildup of seeds in the ground. So when deserts have an unusually wet year after many dry ones, the seeds sprout into a superbloom. This happens as long as it’s not too hot or windy for the flowers to grow.

For animals that eat wildflowers, such as desert tortoises and sphinx moth caterpillars, superblooms are quite a feast. For humans, the blooms make a beautiful spectacle. But it’s important for visitors to not step on the blossoms or pluck them from the ground. That way, they can seed the next flower extravaganza.

In a sentence

Because of climate change bringing record-breaking droughts and heatwaves, superblooms could become even rarer.

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The evolution of land plants about 450 million years ago altered many of Earth’s geologic processes, like weathering and erosion. Due to the lack of evidence for meandering rivers before then, past scientists hypothesized that plants could have caused straight rivers to meander. However, in recent decades, researchers have challenged this idea. They’ve suggested that plants could have changed rivers without causing them to meander.

To understand how vegetation changed rivers in the past, researchers recently studied 49 modern meandering rivers. They sorted these rivers into 3 categories – vegetated, unvegetated, and semi-vegetated – by analyzing color images taken of them from the air. They identified 18 vegetated rivers located in South America, 24 unvegetated rivers in the western United States, and 7 semi-vegetated rivers in China and the Eastern United States. 

To examine the impact of plants on these rivers, the researchers quantified how much each river channel curves, known as its sinuosity. They used opposite banks of each river bend to find its center point, then, using digital maps, drew a line along the river’s trajectory at an equal distance between the bend center points. They used this line to calculate the angle between the river’s curve and the center point. This angle, called the migration angle, shows how a river bend relates to the river’s downstream direction. By measuring it, researchers can tell whether a river is developing more vertically or horizontally, and how sharp its bends are, either of which could be influenced by plants. 

The researchers compared migration angles across each river system to determine how river bends varied between vegetated and unvegetated rivers. They found that vegetated rivers tend to deposit sediments in the river bend, leading to curvier bends that develop horizontally and widen over time. In contrast, unvegetated rivers deposit sediment downstream, which means the rivers bend less and have greater variability in bend width.

The question remained whether plants were the primary cause of these differences or whether other factors were at play. To resolve this, the researchers investigated 3 additional factors. The first was the natural fluctuations in water flow across a river system, called its flow variability. They found that during storms, flow variability caused river bends to move downstream in unvegetated rivers, but not in vegetated rivers. This result suggested that flow variability alone didn’t drive downstream migration, although it can directly impact vegetation. 

The second variable the researchers analyzed was the amount of sediment a river can carry, or its sediment flux. They found that rivers carrying more sediment can erode more banks, also shifting river bends. However, rivers with more sediment but the same level of plant coverage had statistically similar bend angles. Thus, the researchers concluded that sediment flux alone can’t drive bend development, and that the changes were instead dependent on vegetation cover. 

The third variable they analyzed was riverbank strength. The researchers observed rivers with strong banks, made of rock or compacted sediment, and weak banks, made of loose sediment. They observed no difference in river bends with the same vegetation cover but different bank strengths. The researchers concluded that bank strength is also not the primary driver of bend migration in vegetated or unvegetated rivers. 

Of the 4 variables the researchers examined – flow variability, sediment flux, bank strength, and vegetation cover – vegetation cover consistently had the greatest impact on the appearance of meandering rivers. They concluded that meandering rivers could have existed before plants, but would have looked different. Like modern unvegetated rivers, ancient meandering rivers likely had lower-angle bends. As plants evolved and grew on river banks, the bends would have developed differently, becoming curvier like modern vegetated rivers. They suggested that understanding this process provides insight into life on Earth before plants evolved 450 million years ago. 

The post How did land plants change rivers? appeared first on Sciworthy.