Scientists spot underground fungus from space

BLOOMINGTON, Ind., April 1 (UPI) -- Beneath a forest floor, vast communities of fungi stretch out for miles.

Scientists at NASA's Jet Propulsion Laboratory have developed a technique for mapping these fungal networks using satellite imagery.

Mycorrhizal fungi have forged a unique symbiotic relationship with trees and their roots -- collecting and trading soil nutrients for sugars trees generate during photosynthesis. Studying this symbiotic system may help scientists better predict how forests will respond to climate change.

"Nearly all tree species associate with only one of two types of mycorrhizal fungi," Richard Phillips, a biologist at Indiana University, Bloomington, explained in a news release.

The two main types of mycorrhizal fungi respond differently to warming temperatures. To predict which forests are more likely to adapt and thrive as the climate warms -- and which are likely to struggle -- scientists need a more accurate picture of underground fungal ratios.

Field scientists have already done work mapping fungal communities from the ground. As a result, researchers know which trees tend to host which fungi. But counting trees and plotting their distribution within massive forests is tedious, time-consuming work -- work scientists have shown can be done from space.

Different tree species have different spectral signatures, absorbing and reflecting different portions of the light spectrum. To see whether these signatures could help scientists identify fungal communities, researchers compared satellite data with maps of forest fungi communities.

Researchers looked at four forest plots managed by the Smithsonian Institution's Forest Global Earth Observatory. The plots comprised 130,000 trees and 77 species.

Spectral data collected by the Landsat-5 satellite revealed unique seasonal patterns. Different parts of the forest hit different milestones -- spring's first leaves, peak greenness -- at different times. Scientists found the differences corresponded neatly with maps of the two main fungi types.

Satellite imagery allowed scientists to predict the association between trees and fungi with 77 percent success rate.

"That these below-ground agents manifest themselves in changes in the forest canopies is significant," said lead researcher Joshua Fisher. "This allows, for the first time, some light to be shed on their hidden processes."

The new research was published this week in the journal Global Change Biology.