For years, ecosystem restoration on islands has focused almost entirely on reintroducing native plant species. Now, science is reshaping that approach: without soil fungi, many forests simply cannot recover.
This is the key finding of a study published in Current Biology, led by biologist Charlie Cornwallis of Lund University, which highlights a long-overlooked component of ecosystems: underground fungal networks.
Palmyra Atoll: a natural laboratory in the Pacific
The remote Palmyra Atoll, one of the most pristine ecosystems on Earth, has been the focus of major conservation efforts. Here, invasive coconut palms have been removed to allow the native tree species, Pisonia grandis, to regenerate.
However, the study shows that this alone is not enough. The roots of Pisonia trees are deeply dependent on specific symbiotic fungi, found in every sample analyzed. Without them, forest recovery may fail.
A fragile balance between land and ocean
Researchers found that Palmyra’s ecosystem is sustained by a complex web of interactions. Pisonia trees provide nesting sites for millions of seabirds, whose guano enriches the soil. These nutrients eventually reach the ocean, feeding plankton and supporting coral reefs.
At the center of this system are fungi, which enable nutrient exchange between soil and plants. Removing even one link in this chain could destabilize the entire ecosystem.
Fungi and plants: a vital partnership
Globally, mycorrhizal fungi interact with about 80% of plant species, supplying essential nutrients such as nitrogen and phosphorus in exchange for carbon. Yet their role in island ecosystems has remained largely unexplored.
Research conducted with Society for the Protection of Underground Networks and the University of Oxford revealed an extraordinary fungal diversity, including species never documented before.
Rethinking restoration strategies
Scientists emphasize that ecosystem restoration must include not only plants but also their underground partners. In some cases, it may even be necessary to transplant soil rich in beneficial fungi to support vegetation recovery.
This represents a major shift: conservation can no longer ignore what lies beneath the surface.
A deeply interconnected ecosystem
On Palmyra, every component is tightly linked. Land crabs improve fungal diversity through their burrowing, seabirds nourish the forest, and fungi sustain plant life.
It is a delicate but highly efficient system, demonstrating how deeply interconnected natural ecosystems are.
Protecting the unseen to save the visible
The lesson from Palmyra is clear: conservation is not only about visible species. Without fungi and underground networks, entire ecosystems risk collapse.
Understanding and protecting these hidden organisms may be essential to safeguarding island environments—and global biodiversity as a whole.