Global databases used for study

In their recent study, the researchers used global databases to make the first comparison of the composition of 658 regional floras from nearly all parts of the world. In addition, they investigated the influence of biogeographical and anthropogenic (i.e., human-made) factors on the increasing homogenization of regional floras. To assess the floristic uniqueness of individual regions, they took into account both the number of plant species that a region shares or does not share with other regions and the degree to which plant species are related to each other. In doing so, they also included regional evolutionary histories in their analysis.

An important role in the spread of alien plants and the loss of uniqueness of regional floras is played by various biogeographic factors. These factors include the geographic distance between the regions under consideration and their “climatic distance” from each other, according to the study. “The more similar two regions are in terms of climate, the more likely it is that a plant from one region will succeed in establishing itself as a naturalized species in the other region, once geographic barriers have been crossed. In a sense, plants from a region with short climatic distance to their new habitat are ‘climatically pre-adapted’,” Dr Qiang Yang, the lead author of the study, explains the effect.

Political factors as additional driving force

However, anthropogenic factors also have an impact on the spread of alien plants and the global homogenization of regional floras. For instance, the researchers describe that the shared administrative history of some of the regions under consideration plays a role: Regions that are now or had been under the same political administration in the past exhibit greater homogenization in the composition of their floras.

Current examples are regions that are part of the same national territory, such as different regions within the United States. Historical examples, on the other hand, are the European colonial powers and their former colonies. “Between regions of the same national territory or regions with historical colonial ties, there is or at least was lively exchange in the past — in the form of both cargo and passenger traffic. This usually also increases the exchange of plants across geographical borders, be it intentionally, as trade goods or agricultural crops, or unintentionally,” Qiang Yang explains.

More effective biosecurity measures needed

Overall, naturalized alien plant species are driving the global homogenization of regional plant communities, and humans are making a clear contribution by spreading alien plants. “These effects are now evident even in the most remote corners of the world,” reports Dr Mark van Kleunen, Professor of Ecology in the Department of Biology at the University of Konstanz and senior author of the publication. He concludes: “Unless more effective protective measures are taken to counter the ongoing spread and naturalization of alien plants in the future, they will continue to destroy the uniqueness of our ecosystems — making the world a less diverse place.”

Key facts

• Investigation of the uniqueness of regional floras and its worldwide change due to biogeographical and anthropogenic factors based on global databases.
• Naturalization of alien plants is causing a global net loss of uniqueness in regional floras.
• In addition to biogeographical factors, such as geographic or climatic distance, anthropogenic factors, such as administrative relationships between the regions studied, also play a role.
• Funding: German Research Foundation (DFG), German Federal Ministry of Education and Research (BMBF), Czech Science Foundation (GACR) and Academy of Sciences of the Czech Republic (AV ?R), Austrian Science Fund (FWF), Foundation

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Materials provided by University of Konstanz. Note: Content may be edited for style and length.

Apollo 17 astronauts collected the rock sample troctolite 76535 from the Moon’s surface in 1972, and it remains one of the most scientifically valuable samples of the Moon due to its pristine nature. Further, the rock type is widespread on the Moon and likely contains important clues to understanding lunar formation.

William Nelson, lead author of the study and Earth Sciences graduate student in the UH Manoa School of Ocean and Earth Science and Technology (SOEST), and co-authors used a specialized electron microprobe to perform high-resolution analysis of troctolite 76535.

“Previous reports suggest the minerals in the Apollo 17 sample were chemically homogeneous,” said Nelson. “Surprisingly, we found chemical variations within crystals of olivine and plagioclase. These heterogeneities allow us to constrain the earliest, high-temperature cooling histories of these minerals using numerical models.”

SOEST researchers used the UH High-Performance Computing facilities, Mana, to consider the effects of a variety of computer-simulated cooling paths — well over 5 million chemical diffusion models.

“The simulations revealed that these heterogeneities could only survive a relatively short period of time at high temperatures,” said Nelson.

The diffusion patterns preserved in the mineral grains and observed with the microprobe were consistent with a rapid cooling history of no more than 20-million-years at high temperatures. The finding challenges previous estimates of a 100-million-year cooling duration and supports initial rapid cooling of magmas within the lunar crust.

“This is changing our outlook on how an important suite of lunar rocks formed,” said Nelson.

To reconcile high-temperature cooling rates with the generally accepted view of the way in which these rocks formed, the research team proposed that perhaps this rock type is formed by a process called reactive infiltration wherein a melt interacts with rock — changing its chemical and physical makeup.

The study also demonstrates the value of re-examining previously analyzed samples using modern techniques and how quickly new data can reshape our understanding of planetary evolution.

To better understand the observed chemical heterogeneity, the research team is currently investigating how quickly phosphorus can diffuse in olivine crystals. Additionally, they are searching for similar heterogeneities in other Apollo samples.

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Materials provided by University of Hawaii at Manoa. Original written by Marcie Grabowski. Note: Content may be edited for style and length.

The bears’ home range, or the amount of space they need for food and other resources, was around 64% larger from 1999-2016 than it was in 1986-1998, according to a recent study in the journal Ecosphere.

“Having to travel farther means these bears are expending more energy which can threaten their survival,” said Anthony Pagano, a postdoctoral researcher in Washington State University’s School of the Environment and lead author of the study. “If we want to preserve the habitat of these amazing mammals, then we need to focus on the root of the problem, which is slowing global climate change.”

For the study, Pagano and colleagues from the U.S. Geological Survey used satellite tracking data to analyze the movement patterns of female polar bears from 1986-2016 in the Beaufort Sea area north of Alaska.

Their work showed over the last two decades polar bears are having to travel farther north of their traditional hunting grounds on the continental shelf to remain on their receding sea ice habitat.

Extending around 100 miles north of Alaska and Canada, the continental shelf is a shallow water habitat that contains plenty of fish for the bears’ favorite prey, seals.

During the early summer when seals are weaning their pups and most vulnerable to attack, polar bears will often double their body weight from eating the fatty meat.

The researchers’ data shows that as the sea ice over the continental shelf continues to recede earlier and further; the bears are being displaced from this primary foraging habitat and traveling further north into deeper waters where there are fewer seals to prey on.

“The combined impact of having to move farther and farther north with the ice in the summer and then having to move back in the fall and winter as the ice freezes is taking a major toll,” Pagano said. “Our work highlights the worrying impact of sea ice decline on polar bear movement patterns.”

Another interesting finding of the study is that around 20% of the polar bear population in the Beaufort Sea is foregoing their traditional sea ice hunting grounds altogether in the summer and fall. These bears are moving inland along the Alaskan and Canadian coast looking for food such as carrion, berries and sometimes even bowhead whale carcasses that are left on the shore by indigenous residents that hunt the large aquatic mammals.

“Sometimes you’ll have 50 to 100 polar bears that congregate around these whale carcasses and compete with each other for food,” Pagano said. “As more and more bears move on land, I suspect there’ll be a lot more competition for these food resources and we’ll probably start seeing further decreases in abundance and survival.”

Moving forward, Pagano and his colleagues with the U.S Geological Survey plan to conduct further studies of the polar bears moving inland to get a better idea of how they are coping with their new terrestrial habitat.

He said the best thing humans can do to help preserve the southern Beaufort Sea’s 800 or so remaining polar bears is to focus on curbing global carbon emissions which are the main cause behind receding arctic sea ice.

Recent modeling work has shown that if regulations are enacted to reduce these emissions to avoid global warming greater than 2°C or 3.6°F then it could drastically slow the decline of polar bear habitat in the arctic which would in turn help these animals to survive.

“Coming across a polar bear while flying over the arctic in a helicopter is a surreal experience,” Pagano said. “They are incredibly massive and impressive. It is amazing to observe this animal that is so uniquely adapted to exist in this harsh arctic environment. They are worth the effort it will take to preserve them.”

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Materials provided by Washington State University. Original written by Will Ferguson. Note: Content may be edited for style and length.

Until now, reading the electric field of light has been a challenge because of the high speeds at which light waves oscillates. The most advanced techniques, which power our phone and internet communications, can currently clock electric fields at up to gigahertz frequencies — covering the radio frequency and microwave regions of the electromagnetic spectrum. Light waves oscillate at much higher rates, allowing a higher density of information to be transmitted. However, the current tools for measuring light fields could resolve only an average signal associated with a ‘pulse’ of light, and not the peaks and valleys within the pulse. Measuring those peaks and valleys within a single pulse is important because it is in that space that information can be packed and delivered.

“Fiber optic communications have taken advantage of light to make things faster, but we are still functionally limited by the speed of the oscilloscope,” says Physics Associate Professor Michael Chini, who worked on the research at UCF. “Our optical oscilloscope may be able to increase that speed by a factor of about 10,000.”

The team’s findings are published in this week’s Nature Photonics journal.

The team developed the device and demonstrated its capability for real-time measurement of the electric fields of individual laser pulses in Chini’s lab at UCF. The next step for the team is to see how far they can push the speed limits of the technique.

The lead author of the paper is UCF postdoctoral scholar Yangyang Liu. Other authors include physics alums Jonathan Nesper ’19 ’21MS, who earned his bachelor’s in math and master’s in physics; Shima Gholam-Mirzaei ’18MS ’20PhD; and John E. Beetar ’15 ’17MS ’20PhD.

Gholam-Mirzaei is now a postdoctoral researcher at the Joint Attosecond Science Laboratory at the National Research Council of Canada and University of Ottawa and Beetar is completing a postdoc at the University of California at Berkeley.

Chini had the idea for the single-shot waveform measurement scheme and oversaw the research team. Liu led the experimental effort and performed most of the measurements and simulations. Beetar assisted with the measurements of the carrier-envelope phase dependence. Nesper and Gholam-Mirzaei assisted with the construction of the experimental setup and with the data collection. All authors contributed to the data analysis and wrote the journal article.

The work was supported primarily through a grant from the Air Force Office of Scientific Research under Award No. FA9550-20-1-0284, while Gholam-Mirzaei was supported by the Army Research Office under Award No. W911NF-19-1-0211.

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Materials provided by University of Central Florida. Original written by Zenaida Gonzalez Kotala. Note: Content may be edited for style and length.