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Western hemlock forest
Western hemlock forest

Secret Keepers of the Forest

Seattle Times Newspapers in Education

When exploring a forest, whether in a National Park or your own backyard, it's common to encounter a variety of animals, trees, and water sources among your green surroundings. However, there is one part of this ecosystem that probably would not catch your eye.

Underneath the surface, below the ground we walk on, lays a web of lacy threads called mycelium. Many creatures, including humans, depend on this delicate network of fungus for survival.

Mycelium is made up of a web of tiny filaments called hyphae. These hyphae can branch out through soil or dead wood, expanding an entire system by over half a mile each day.

Though you may not be aware of mycelium when you visit a forest, you would notice differences in a wooded setting if it did not exist. The first clue would be the disappearance of mushrooms. Mushrooms sprout directly from mycelium. These fruiting bodies vary from enjoyably edible to lethally poisonous to simply curious.

"Ecosystems don't stay in place, things are always changing. People wherever they live have a lot of influence over other areas. There aren't too many square inches on the earth that haven't been affected by human civilization in one way or another."
- Steve Acker

One type of fungus that falls under the last category is called "fairy rings." These are mushroom circles that expand outward each year, reflecting the outer boundary of the mycelium in the ground. The largest fairy rings recorded at Olympic National Park spread over 600 feet in diameter, meaning those fungal systems are 500 to 700 years old.

While mushrooms make up only a small part of the human diet, some forest animals rely heavily on fungi. Northern flying squirrels and other rodents dig up truffles, a mushroom which fruits underground, which give off spicy, garlicky or cheesy aromas. Fungi flesh contains 30 to 100 times more potassium, phosphorus, and nitrogen than is available in plant foliage, making its consumers a healthy meal for predators like the Northern spotted owl.

Animals aren't the only ones who rely on fungi. 95% of all green plants depend upon at least one fungus to survive. Olympic Peninsula temperate rain forests have been nourished by fungi for more than 5,000 years, making them the largest rainforest stands of old growth conifers left south of Alaska.

As you can see, the disappearance of these complicated fungal systems would devastate plant and wild animal populations. It would also mean a loss of more than just mushrooms for us humans. From ecosystems connected by these microscopic forest fungi, we utilize yew bark compounds to treat tumorous cancer, use timber such as the Sitka spruce, and most importantly, receive the clean water and fresh air our bodies depend on.

Coral fungus
Ramaria celerivirescens

Luckily, mycelium networks continue to do their important job within the interdependent web of life. Just as the forests could not function without mycorrhizae, fungus could not survive without forest ecosystems. Because mycelium cannot photosynthesize to get energy from the sun, it forms relationships with other organisms to obtain nutrients.

These feeding relationships can be simple, such as when mycorrhizal fungi connect to tree roots and other plants to draw in sugars, or more advanced like the farming techniques used by lichenized fungi to harvest algae or bacteria for sustenance. Crustose lichens even disintegrate rock using an acid secreted by fungal threads, penetrating more than a half-inch into the rock to obtain food.

These feeding processes demonstrate how this small organism does not merely affect many aspects of nature; it also relies on them. The key role mycelium plays in forest ecosystems reveals that even the species that frequently go unnoticed by humans can play a vital role in ecosystems.


Saling, Ann. The Great Northwest Nature Factbook: A guide to the Region's Remarkable Animals, Plants & Natural Features. 1999: WestWinds Press, Portland.
North Coast and Cascades Research Learning Network
Imagine living laboratories where science and education are combined to increase our knowledge and understanding of the natural world and our relationship with it. Picture places where natural and cultural scientists conduct groundbreaking research that helps national park managers protect the seashores, forests, sub-alpine meadows and other natural and cultural resources in their care.
To see this vision through, the National Park Service has established thirteen Research Learning Networks and Centers around the country. The North Coast and Cascades (NCC) Research Learning Network, established in 2001, is one of the earliest established learning networks. The Network is formed through a partnership of eight network parks with universities and colleges, non-profit organizations, local schools and state and federal agencies. The North Coast and Cascades Network stretches across western Washington from North Cascades to Olympic, San Juan Island, Ebey's Landing, Klondike: Seattle, to the Columbia River Basin with Fort Vancouver and Lewis and Clark national park sites.
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