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What Satellite Images of Trees Can Reveal About Underground Fungus

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Fungi are a lot like glaciers: Nearly all the action takes place below the surface. Beneath the soil, fungi tangle with trees, forming mutually beneficial relationships. Scientists recently used these close relationships and mapped tree health with the help of fungus data. They published their findings in the journal Global Change Biology.

"Every tree species has a distinct spectral signal, a kind of measurable aura," ecologist Sean McMahon said in a press statement. "Now we can tell who their underground friends are, an indicator of their nutrient status, from the sky." McMahon is temperate program coordinator of the Smithsonian’s Forest Global Earth Observatory (ForestGEO) network, which monitors the growth and survival of millions of trees on five continents.

Nearly all of those trees are involved in close relationships with fungi. The unseen world underground is a vast mesh of tree roots and threadlike fungal hyphae. It’s a good system; the fungi help trees get the water and nutrients they need, then reap the sugary benefits of the trees’ photosynthesis. Two types of fungus interact this way: ectomycorrhizal fungi (ECM), which hang out near and on tree roots, and arbuscular mycorrhizal fungi (AM), which actually dig into the cells of tree roots.

AM fungus in the roots of a flax plant. Image credit: MSturmel via Wikimedia Commons // Public Domain

A team of researchers from across the United States wondered what the fungi could reveal about their tree buddies. They compared maps from Landsat satellites with records on the fungal partners of 130,000 trees at research sites in Virginia, Indiana, Wisconsin, and Missouri.

"We discovered that groups of tree species associating with one type of fungi were spectrally distinct from groups of species associating with other types of fungi," said the paper’s first author, California Institute of Technology postdoctoral researcher Joshua Fisher. In other words, the trees’ under-the-covers, fungal hanky panky affected the way they appeared on the maps. Trees with AM pals have more phosphorus in their leaves. They make leaves sooner, and those leaves decay faster, which means faster nutrient recycling for everyone involved. ECM-associated trees, on the other hand, take longer to process nutrients.

Fisher and his colleagues realized that this could mean a new way of measuring and tracking forest health. Previous studies had shown that certain tree species preferred one type of fungus over another, but the sheer amount of labor involved in checking each tree/fungus pair in a forest is prohibitive.

The researchers tested their theory by trying to determine based on satellite maps which tree-fungus pairings grew in their forest research sites. They were able to predict the correct pairings 77 percent of the time, which is pretty impressive considering they were looking at these underground relationships from space.

Encouraged, the team will continue testing their concept in another 63 ForestGEO sites. 

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Ethan Miller/Getty Images
Look Up! The Orionid Meteor Shower Peaks This Weekend
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Ethan Miller/Getty Images

October is always a great month for skywatching. If you missed the Draconids, the first meteor shower of the month, don't despair: the Orionids peak this weekend. It should be an especially stunning show this year, as the Moon will offer virtually no interference. If you've ever wanted to get into skywatching, this is your chance.

The Orionids is the second of two meteor showers caused by the debris field left by the comet Halley. (The other is the Eta Aquarids, which appear in May.) The showers are named for the constellation Orion, from which they seem to originate.

All the stars are lining up (so to speak) for this show. First, it's on the weekend, which means you can stay up late without feeling the burn at work the next day. Tonight, October 20, you'll be able to spot many meteors, and the shower peaks just after midnight tomorrow, October 21, leading into Sunday morning. Make a late-night picnic of the occasion, because it takes about an hour for your eyes to adjust to the darkness. Bring a blanket and a bottle of wine, lay out and take in the open skies, and let nature do the rest.

Second, the Moon, which was new only yesterday, is but a sliver in the evening sky, lacking the wattage to wash out the sky or conceal the faintest of meteors. If your skies are clear and light pollution low, this year you should be able to catch about 20 meteors an hour, which isn't a bad way to spend a date night.

If clouds interfere with your Orionids experience, don't fret. There will be two more meteor showers in November and the greatest of them all in December: the Geminids.

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11-Year-Old Creates a Better Way to Test for Lead in Water
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In the wake of the water crisis in Flint, Michigan, a Colorado middle schooler has invented a better way to test lead levels in water, as The Cut reports.

Gitanjali Rao, an 11-year-old seventh grader in Lone Tree, Colorado just won the 2017 Discovery Education 3M Young Scientist Challenge, taking home $25,000 for the water-quality testing device she invented, called Tethys.

Rao was inspired to create the device after watching Flint's water crisis unfold over the last few years. In 2014, after the city of Flint cut costs by switching water sources used for its tap water and failed to treat it properly, lead levels in the city's water skyrocketed. By 2015, researchers testing the water found that 40 percent of homes in the city had elevated lead levels in their water, and recommended the state declare Flint's water unsafe for drinking or cooking. In December of that year, the city declared a state of emergency. Researchers have found that the lead-poisoned water resulted in a "horrifyingly large" impact on fetal death rates as well as leading to a Legionnaires' disease outbreak that killed 12 people.

A close-up of the Tethys device

Rao's parents are engineers, and she watched them as they tried to test the lead in their own house, experiencing firsthand how complicated it could be. She spotted news of a cutting-edge technology for detecting hazardous substances on MIT's engineering department website (which she checks regularly just to see "if there's anything new," as ABC News reports) then set to work creating Tethys. The device works with carbon nanotube sensors to detect lead levels faster than other current techniques, sending the results to a smartphone app.

As one of 10 finalists for the Young Scientist Challenge, Rao spent the summer working with a 3M scientist to refine her device, then presented the prototype to a panel of judges from 3M and schools across the country.

The contamination crisis in Flint is still ongoing, and Rao's invention could have a significant impact. In March 2017, Flint officials cautioned that it could be as long as two more years until the city's tap water will be safe enough to drink without filtering. The state of Michigan now plans to replace water pipes leading to 18,000 households by 2020. Until then, residents using water filters could use a device like Tethys to make sure the water they're drinking is safe. Rao plans to put most of the $25,000 prize money back into her project with the hopes of making the device commercially available.

[h/t The Cut]

All images by Andy King, courtesy of the Discovery Education 3M Young Scientist Challenge.


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