Introduction
Palmyra Atoll in the North Pacific is one of the most remote island systems on Earth. A native rainforest tree on the island performs a critical ecological service by providing nesting sites for thousands of seabirds, whose guano fuels the surrounding coral reefs. However, a new study revealed that this entire cycle depends on an invisible partner: Symbiotic mycorrhizal fungi.
The Importance of Fungi
Researchers mapped the fungal diversity across the atoll and discovered the native pisonia (Pisonia grandis) trees have a 100% association with a specific genus of fungi called Tomentella — meaning the trees depend on the fungi to survive. These fungi capture intense pulses of nitrogen and phosphorus from bird guano that would otherwise wash into the ocean.
This relationship was present in every tree the team sampled. According to study co-author Alex Wegmann, "most ectomycorrhizal fungi struggle in extremely nutrient-rich soils, but the Tomentella fungi associated with Pisonia appear to be adapted to the high phosphorus levels created by seabird guano".
Implications for Restoration
The discovery has major implications for the ongoing effort to restore Palmyra’s native forests by removing 1.5 million invasive coconut palms. The study found that Tomentella abundance drops off sharply when there are more than 250 meters (820 feet) away from a pisonia tree. Therefore, natural regeneration might fail in large areas cleared of coconut palms, because the necessary fungi aren’t present in the soil.
Conclusion
The role of symbiotic mycorrhizal fungi in the restoration of Palmyra Atoll rainforests is crucial. Understanding this relationship is fundamental to the success of restoration efforts and for maintaining biodiversity and ecosystem health.
Source / Reference: Mongabay