Abundant Mushrooms

By Scott Fitzpatrick on Friday, September 29, 2006.

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A bumper crop of mushrooms in fall, interestingly enough, doesn't start with fungi but with nearby trees.

Hi. This is Scott Fitzpatrick from New Hampshire Audubon, bringing you Something Wild.

Have you ever wondered why some fall seasons produce bumper crops of mushrooms?

It turns out that it has a lot to do with the trees.

Mushrooms are actually just the temporary reproductive structures of a fungus - kind of like its flower. Most of its permanent body exists underground, as an extensive network of fine, root-like filaments. This subterranean portion can be humongous. One individual in Oregon has been estimated to cover 2200 acres.

Many fungi live in a partnership with a plant, often a tree. Trees create sugars through photosynthesis, but the fungi get their energy from breaking down decomposing organic matter, and from the trees themselves. The fungal filaments provide the trees with minerals and other nutrients. In return, the tree roots deliver sugar energy to the fungus.

The coming of fall triggers changes in the trees that lead to the production of mushrooms. In the temperate areas of the world, such as in New Hampshire, the decreasing daylight and dropping temperatures cause the trees to prepare for winter. They stop using energy for growth, and divert it to the production of the buds that will become next year's leaves.

After these buds have been set, the tree sends its remaining sugars down to the roots for safe storage over the winter, to use in next spring's growth spurt. The fungus, waiting below ground, depends on these sugars for the extra boost of energy it needs to form mushrooms. And it is not until fall that the trees divert enough sugars below ground to allow the fungi to produce abundant mushrooms.

So a good year for trees, one with the right amount of rain and sunlight, is usually a great year for mushrooms.

For Something Wild, I'm Scott Fitzpatrick.

Something Wild is a joint production of New Hampshire Audubon, New Hampshire Public Radio and the Society for the Protection of New Hampshire Forests.