Tree Tips--Fungi in the Forest--12/28/01

Printed in the Mendocino County Observer.

"Fun Guy" in the Forest

December 26, 2001

Do you ever wonder how to pronounce "fungi"? Just remember what the fern said to the mushroom: "You're such a fun guy!"

"Fungi" is of course the plural of "fungus" (some people say "funguses", which is also correct). There are many kinds of fungi, including molds and mildews, mushrooms, rusts, etc. Some common characteristics of fungi is that they don't have chlorophyll, help decompose other material, and reproduce by means of spores.

In the forest, fungi are important for two reasons. One, they are decomposers. In many forest soils, they are the majority of the decomposers, breaking down limbs, logs, leaves, and other dead material. Some fungi form what look like long, thin strings, called hyphae. These are often white or yellowish and, particularly in the upper layers of soil, can be very abundant.

One study in Scotland years ago measured over 18 feet of hyphae (5.6 meters) per cubic centimeter of soil. The density of hyphae in our soils isn't so high, but next time you are in the woods, run your hands through the soil. If you feel or see little whitish or yellowish strands that snap, those are the hyphae of soil fungi. (Some fungi have hyphae that are dark-colored, but these can be confused with fine plant roots.)

The other important function of fungi is in helping plants take up nutrients. Certain kinds of fungi form a special relationship with tree roots that helps both the fungi and the tree. It is a symbiotic (win-win) relationship in which the fungi decomposes material in or near the tree roots, and for reasons not entirely understood, the fungi allows the tree roots to take up nutrients more efficiently because of the fungi.

Scientists have found that seedling survival, height and weight are all much higher in seedlings that are planted in soils with these specialized fungi than those that aren't. The effect of the fungi has been likened to the effect of fertilizing with nitrogen.

Next time you are in the woods, look in the soil and on the logs to see if you can spot a forest "fun guy" or two.

Clare Nunamaker is a Registered Professional Forester and member of NorCal SAF, CLFA, and the Forest Stewards Guild.