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Tropical rainforests today are biodiversity hotspots and play an important role in the world’s climate systems. A new study published today in Science sheds light on the origins of modern rainforests and may help scientists understand how rainforests will respond to a rapidly changing climate in the future.
The study led by researchers at the Smithsonian Tropical Research Institute (STRI) shows that the asteroid impact that ended the reign of dinosaurs 66 million years ago also caused 45% of plants in what is now Colombia to go extinct, and it made way for the reign of flowering plants in modern tropical rainforests.
“We wondered how tropical rainforests changed after a drastic ecological perturbation such as the Chicxulub impact, so we looked for tropical plant fossils,” said Mónica Carvalho, first author and joint postdoctoral fellow at STRI and at the Universidad del Rosario in Colombia. “Our team examined over 50,000 fossil pollen records and more than 6,000 leaf fossils from before and after the impact.”
In Central and South America, geologists hustle to find fossils exposed by road cuts and mines before heavy rains wash them away and the jungle hides them again. Before this study, little was known about the effect of this extinction on the evolution of flowering plants that now dominate the American tropics.
Carlos Jaramillo, staff paleontologist at STRI and his team, mostly STRI fellows — many of them from Colombia — studied pollen grains from 39 sites that include rock outcrops and cores drilled for oil exploration in Colombia, to paint a big, regional picture of forests before and after the impact. Pollen and spores obtained from rocks older than the impact show that rainforests were equally dominated by ferns and flowering plants. Conifers, such as relatives of the of the Kauri pine and Norfolk Island pine, sold in supermarkets at Christmas time (Araucariaceae), were common and cast their shadows over dinosaur trails. After the impact, conifers disappeared almost completely from the New World tropics, and flowering plants took over. Plant diversity did not recover for around 10 million years after the impact.
Leaf fossils told the team much about the past climate and local environment. Carvalho and Fabiany Herrera, postdoctoral research associate at the Negaunee Institute for Conservation Science and Action at the Chicago Botanic Garden, led the study of over 6,000 specimens. Working with Scott Wing at the Smithsonian’s National Museum of Natural History and others, the team found evidence that pre-impact tropical forest trees were spaced far apart, allowing light to reach the forest floor. Within 10 million years post-impact, some tropical forests were dense, like those of today, where leaves of trees and vines cast deep shade on the smaller trees, bushes and herbaceous plants below. The sparser canopies of the pre-impact forests, with fewer flowering plants, would have moved less soil water into the atmosphere than did those that grew up in the millions of years afterward.
“It was just as rainy back in the Cretaceous, but the forests worked differently.” Carvalho said.
The team found no evidence of legume trees before the extinction event, but afterward there was a great diversity and abundance of legume leaves and pods. Today, legumes are a dominant family in tropical rainforests, and through associations with bacteria, take nitrogen from the air and turn it into fertilizer for the soil. The rise of legumes would have dramatically affected the nitrogen cycle.
Carvalho also worked with Conrad Labandeira at the Smithsonian’s National Museum of Natural History to study insect damage on the leaf fossils.
“Insect damage on plants can reveal in the microcosm of a single leaf or the expanse of a plant community, the base of the trophic structure in a tropical forest,” Labandeira said. “The energy residing in the mass of plant tissues that is transmitted up the food chain — ultimately to the boas, eagles and jaguars — starts with the insects that skeletonize, chew, pierce and suck, mine, gall and bore through plant tissues. The evidence for this consumer food chain begins with all the diverse, intensive and fascinating ways that insects consume plants.”
“Before the impact, we see that different types of plants have different damage: feeding was host-specific,” Carvalho said. “After the impact, we find the same kinds of damage on almost every plant, meaning that feeding was much more generalistic.”
How did the after effects of the impact transform sparse, conifer-rich tropical forests of the dinosaur age into the rainforests of today — towering trees dotted with yellow, purple and pink blossoms, dripping with orchids? Based on evidence from both pollen and leaves, the team proposes three explanations for the change, all of which may be correct. One idea is that dinosaurs kept pre-impact forests open by feeding and moving through the landscape. A second explanation is that falling ash from the impact enriched soils throughout the tropics, giving an advantage to the faster-growing flowering plants. The third explanation is that preferential extinction of conifer species created an opportunity for flowering plants to take over the tropics.
“Our study follows a simple question: How do tropical rainforests evolve?” Carvalho said. “The lesson learned here is that under rapid disturbances — geologically speaking — tropical ecosystems do not just bounce back; they are replaced, and the process takes a really long time.”
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The institute furthers the understanding of tropical biodiversity and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.
Tampa, Florida (WFLA) — SpaceX made history on Wednesday night when it launched the world’s first all-civil mission to get going from the Space Coast, Florida.
The Inspiration4 mission took off from Launch Complex 39A at NASA’s Kennedy Space Center around 8:03 pm on Wednesday. The four crew members on the SpaceX Dragon spacecraft were launched onto a reusable Falcon 9 rocket and later separated from the spacecraft and landed on the drone.
The mission’s five-hour launch window began at 8:02 EST. The window was very large, as the crew was sent to orbit the Earth rather than the International Space Station, and therefore did not have such strict time constraints.
The crew is set to travel 350 miles above the surface of the Earth, about 100 miles higher than the International Space Station.
“This is important and historic, because it’s the best time humans have been in orbit since the Hubble Space Telescope mission,” said Benjireed, SpaceX’s manned spaceflight director.
The crew will spend three days in orbit to participate in research experiments on human health and performance. We hope that the results of our research will apply not only to future space flight, but also to human health here on Earth.
Inspiration4’s main goal is to provide and inspire support for St. Jude Children’s Research Hospital. They want to raise $ 200 million for St. Jude in a three-day mission.
According to SpaceX, each of the four members of the crew was chosen to represent the pillars of a mission of prosperity, generosity, hope and leadership. The Inspiration 4 crew and the pillars they represent are:
SpaceX trained all four crew members as commercial astronauts on Falcon 9 and Dragon spacecraft. The crew was trained in orbital mechanics, microgravity, weightlessness, other stress tests, emergency preparedness, and spacesuit training.
The mission was funded by Isaacman in a private transaction with SpaceX. Isaacman has also invested $ 100 million towards a funding target for the St. Jude mission.
Inspiration4 Lift Off: SpaceX Launches World’s First All-Citizen Mission in Earth’s Orbit
Source link Inspiration4 Lift Off: SpaceX Launches World’s First All-Citizen Mission in Earth’s Orbit
Researchers have created a winged microchip around the size of a sand grain that may be the smallest flying device yet made, Vice has reported. They’re designed to be carried around by the wind and could be used in numerous applications including disease and air pollution tracking, according to a paper published by Nature. At the same time, they could be made from biodegradable materials to prevent environmental contamination.
The design of the flyers was inspired by spinning seeds from cottonwood and other trees. Those fall slowly by spinning like helicopters so they can be picked up by the wind and spread a long distance from the tree, increasing the range of the species.
The team from Northwest University ran with that idea but made it better, and smaller. “We think we’ve beaten biology… we’ve been able to build structures that fall in a more stable trajectory at slower terminal velocities than equivalent seeds,” said lead Professor John A. Rogers. “The other thing… was that we were able to make these helicopter flyer structures that are much smaller than seeds you would see in the natural world.”
They’re not so small that the aerodynamics starts to break down, though. “All of the advantages of the helicopter design begin to disappear below a certain length scale, so we pushed it all the way, as far as you can go or as physics would allow,” Rogers told Vice. “Below that size scale, everything looks and falls like a sphere.”
The devices are also large enough to carry electronics, sensors and power sources. The team tested multiple versions that could carry payloads like antenna so that they could wireless communicate with a smartphone or each other. Other sensors could monitor things like air acidity, water quality and solar radiation.
The flyers are still concepts right now and not ready to deploy into the atmosphere, but the team plans to expand their findings with different designs. Key to that is the use of biodegradable materials so they wouldn’t persist in the environment.
“We don’t think about these devices… as a permanent monitoring componentry but rather temporary ones that are addressing a particular need that’s of finite time duration,” Rogers said. “That’s the way that we’re envisioning things currently: you monitor for a month and then the devices die out, dissolve, and disappear, and maybe you have to redeploy them.”
NASA is splitting its human spaceflight department into two separate bodies – one centered on big, future-oriented missions to the moon and Mars, the other on the International Space Station and other operations closer to Earth.
The reorganization, announced by NASA chief Bill Nelson on Tuesday, reflects an evolving relationship between private companies, such as SpaceX, that have increasingly commercialised rocket travel and the federal agency that had exercised a US monopoly over spaceflight for decades.
Nelson said the shake-up was also spurred by a recent proliferation of flights and commercial investment in low-Earth orbit even as NASA steps up its development of deep-space aspirations.
“Today is more than organizational change,” Nelson said at a press briefing. “It’s setting the stage for the next 20 years, it’s defining NASA’s future in a growing space economy.”
The move breaks up NASA’s Human Exploration and Operations Mission Directorate, currently headed by Kathy Leuders, into two separate branches.
Leuders will keep her associate administrator title as head of the new Exploration Systems Development Mission Directorate, focusing on NASA’s most ambitious, long-term programs, such as plans to return astronauts to the moon under project Artemis, and eventual human exploration of Mars.
A retired deputy associate administrator, James Free, who played key roles in NASA’s space station and commercial crew and cargo programs, will return to the agency as head of the new Space Operations Mission Directorate.
His branch will primarily oversee more routine launch and spaceflight activities, including missions involving the space station and privatization of low-Earth orbit, as well as sustaining lunar operations once those have been established.
“This approach with two areas focused on human spaceflight allows one mission directorate to operate in space while the other builds future space systems,” NASA said in a press release announcing the move.
The announcement came less than a week after SpaceX, which had already flown numerous astronaut missions and cargo payloads to the space station for NASA, launched the first all-civilian crew ever to reach orbit and returned them safely to Earth.
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