Fungi in the soil: mushrooms, mycelia and mycorrhiza
| Posted on September 9, 2013 at 2:55 PM |
Published November 18, 2011COLUMNISTS
Phillipa Gardiner/Think Tank
In the cool, damp and dark of the autumn forest, fungi are flourishing everywhere. Don’t be fooled — there is far more to a fungus than the humble mushroom.
A mushroom is merely the reproductive body of a fungus, produced occasionally to release spores into the air. The majority of the fungus lives under the ground as an interconnected network of thread-like filaments called hyphae. A single network, called a mycelium, can cover vast areas under the soil. One mycelium in eastern Oregon was recorded at 2,400 acres in size — equivalent to 1,665 football fields.
Fungi appear to be closely related to plants. However, while plants are able to harness sunlight to create their own food, fungi are more like animals, needing to obtain carbon compounds for growth and energy from other sources.
Soil fungi have evolved several ways to obtain essential nutrients. Some fungi are parasites or pathogens — infecting plants or trees and living off their bodies (an example is the fungi that cause root rot). Others are decomposers, secreting enzymes to break down wood, leaf litter and other organic matter. This releases nutrients for the fungi, and helps recycle nutrients into usable forms for other life forms to use.
Another type of fungi — known as mycorrhizal fungi — has evolved a mutually beneficial partnership with plants and trees. Their hyphae form a sheath around their roots, in some cases penetrating plant cells. The fungus uses its network of hyphae to absorb minerals and water from the soil, delivering some to the plant. In exchange, the plant supplies the fungus with carbon and energy in the form of simple sugars. The fungi are also thought to protect trees against pathogens and extreme environmental temperatures, while contributing to soil structure and ecology.
This symbiotic relationship has evolved over a very long time — it is thought that fungi enabled plants to move from the water to the land half a billion years ago. In British Columbia, all major timber trees and many ornamentals are symbiotically dependant on a relationship with fungi (excepting some species in the families Cupressaceae and Aceraceae). Without fungi, the incredible diversity of plant life that surrounds Squamish may not exist at all.
Fungi can be negatively affected by a number of human practices or susceptible to human interventions including air pollution, use of fertilizers, clear-cut logging, fire management and non-sustainable harvesting of edible mushrooms. Unfortunately, as the majority of fungi are hidden under the ground, their contribution can be overlooked. Research into fungi in ecosystems and protection of endangered species is therefore an extremely important area of research. (Note: We should also include research into the negative effects of mountain biking activities, especially their very invasive and consumptive trail building techniques. They may be doing as much, if not more damage than "fire management" activities. Mountain bikers are very fond of the use of heavy-duty fire/wildland "management" tools, for their style of trail building.)
The next time you go for a walk, keep an eye out for mushrooms. If you find one, consider the part of the fungus that you cannot see — the branching mycelium possibly intertwined with the roots of surrounding trees. The mushroom is a humble but essential piece of the complex soil story hidden beneath your feet.
“Mother trees” use fungal systems to feed the forest:
Suzanne Simard, a forest ecologist at the University of British Columbia, helped make the major finding, first published in the journal Nature, that trees and plants communicate. She discovered an underground web of fungi that connects trees and plants together and shuttles resources, allowing trees to help one another survive and thrive.
Suzanne Simard’s research has shown that without “Mother Trees” — the big trees that dominate forests and are connected to all other trees — efforts at regeneration often fail. Her latest results reveal that when a Mother Tree is cut down, the survival rate of new seedlings is very low. The implications for the forest industry and conservation groups are huge: conserve Mother Trees and preserve mycorrhizal networks, or we could lose our forests...
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