To Restore an Island Paradise, Add Fungi

For the last two decades, conservationists on the remote Pacific atoll of Palmyra have been working to uproot invasive palm trees and restore native wildlife. A new study finds that native fungi could be instrumental to that process.

Palmyra Atoll, a U.S. territory, was stripped of its forests in the 19th century to plant palm trees for the production of coconut oil. Even after its plantations were abandoned, palms continued to dominate the atoll, displacing native trees. Further threatening wildlife was the inadvertent introduction by the U.S. military of black rats, which destroyed seedlings and ate seabird hatchlings and crabs.

Conservationists working with the U.S. Fish and Wildlife Service have since made great progress in undoing this damage. In 2011, they eradicated black rats, and by 2022, they had removed 1.5 million coconut palms. But to fully restore Palmyra’s native Pisonias, they may need the help of underground fungi that supply nutrients to trees. 

When a team of researchers sampled the soil beneath Pisonia trees on Palmyra, they discovered rare mycorrhizal fungi, including several species found nowhere else on Earth. Scientists also identified several areas where fungi could be transplanted to give a boost to Pisonia seedlings. The findings were published in the journal Current Biology.

“Until now, restoration has almost exclusively focused on native plants. That is changing,” said coauthor Toby Kiers of Vrije University Amsterdam. Kiers, who is at the forefront of a push to recognize fungi on the same level as plants, added, “Research is showing how successful restoration involves introducing native plants together with native fungi.”

On atoll islands across the Pacific, invasive coconut palms have not only displaced native flora but also left islands more vulnerable to rising seas. Native broadleaf forests provide a home to seabirds, whose guano washes into the ocean, nourishing coral reefs. Reefs fed by guano grow faster, supplying more sediment to islands, which helps them stay above the waterline.

“The health of Palmyra’s coral reefs ultimately depends on seabirds, which depend on Pisonia trees for nesting, which depend on fungi,” said Charlie Cornwallis of Lund University in Sweden, lead author of the new study. “Remove any link in that chain and the whole system could unravel.” 

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