Mycorrhizae: What foresters _MUST_ learn about fungi
truffler1635 at truffler1635 at
Wed Apr 19 02:21:22 EST 2000

The following article is from the Winter, 2000 issue of Focus on
Forestry (The Magazine for the Friends and Alumni of the College of
Forestry at Oregon State University)

People Profiles: Mike Amaranthus

There’s no shortage of gee-whiz facts about soil fungi, and Mike
Amaranthus (Ph.D. ‘89) knows them all. “Several miles of fungal
filaments can be present in a thimbleful of temperate-forest soil,” he
says. “There can be 10,000 species of fungi in a square foot. When you
consider the below ground component, temperate forests have far more
species diversity than tropical forests.”
The sheer biomass of these soil fungi – neither plant nor animal,
but owning their own kingdom – can be staggering, he says. A hectare of
ground in an old-growth Douglas-fir stand can contain 4,200 kilograms of
fungal mycelium. That 9,240 pounds, dry weight, of itty-bitty threads in
a blanket of soil the size of two football fields. (Poster’s note:
remember that mycelium, like mushrooms, are over 90% water by weight.)
“And besides,” he says, “the spores are beautiful.” Indeed they are.
Peering through a microscope in Amaranthus’ office laboratory, a visitor
sees a mass of crimson, egg-shaped spores of the fungus Glomus
intraradices nestling inside the root of a marigold plant like bright
marbles inside a nylon stocking. Fungal spores come in a universe of
sizes, shapes, and colors: ping-pong balls, star bursts, or thistle
heads; smooth, bumpy, wrinkled, or pitted; white, yellow, olive, red,
green, gray, and every color in between.
Amaranthus, 44, is the president and chief scientist of Mycorrhizal
Applications Inc., a 3-year-old Grants Pass company that extracts and
markets these beneficial soil fungi to nurseries, timber companies,
landscapers, and organic farmers.
The real beauty of mycorrhizal fungi, as they are called, is more
than skin-deep. When they connect with the roots of plants, they can
increase the plant’s ability to take in water and food by 10 to 1,000
times. They help plants resist diseases and pests. they emit chemicals
into the soil to unlock hard-to-extract micronutrients like iron and
phosphorus. They produce organic “glues” that make the soil more clumpy
and porous, improving its structure and resiliency.
In another corner of his lab, Amaranthus picks up two longleaf pine
seedlings. One was fed with nitrogen fertilizer; the other got a shot of
the right mix of fungi instead. The inoculated seedling is visibly more
vigorous on top, and its roots are three times as bushy as those of the
other “We’ve inoculated 40 million of these in the South, where they’re
trying to restore the longleaf pine ecosystem,” says Amaranthus.
“Inoculation typically costs less than a penny a seedling.”
“Mycorrhizae” is the word for the tangle of tissue that forms when
the threads of specialized soil fungi get together with plant roots. In
forests, many of these fungi form mushrooms, truffles, and puffballs.
These “fruits” contain the spores or “seeds” of the fungus. Mycorrhizae
represent a 400-million-year-old, evolving relationship, one that
scientists think made it possible for aquatic plants to keep themselves
watered and thus become established on dry land.
Mycorrhizae are everywhere in relatively undisturbed soils – more
than 90 percent of the world’s plants form them around or inside the
roots. The more numerous ectomycorrhizal species (“ecto-” is a prefix
meaning “outside”) attach themselves to the outsides of conifer roots.
The other major category, endomycorrhize, colonize root tissue from the
inside. These species associate themselves with nonconiferous plants –
hardwood trees, shrubs, herbs, and grasses.
“Most natural settings don’t lack for mycorrhizae,” says Amaranthus.
But they tend to be absent in disturbed soils like construction sites,
heavily compacted logging sites, or sterilized nursery soils. Because
they help restore the soil’s health, mycorrhizae offer an alternative to
heavy fertilizer and pesticide use.
Until recently, says Amaranthus, nursery managers and other growers
have had few alternatives to large-scale use of fertilizers and
pesticides. “We’re finding that if you give them an economical way to
grow plants and conserve resources, most will choose it.”
To prepare their products, crews collect the fruiting bodies of the
fungi in what Amaranthus calls “sporchards” – areas where inoculated
seedlings have been outplanted, introducing the fungi to the site. The
company then custom-blends the fungi according to what kinds of plants
the customer is growing. Forest nurseries growing Douglas-fir get one
blend, nurseries growing pine seedlings get another; landscaping
nurseries get yet another.
Amaranthus’ work has caught the eye of the conservation organization
Sustainable Northwest, which this year recognized him with its Founders
of the New Northwest award. Perhaps a more telling honor is that two
fungal genera (Mycoamaranthus and Amogaster) and one species
(Gastrosuillus amaranthii) have been named after him.
Amaranthus can’t quite explain his passion for the subterranean
universe of living things. He grew up in the Los Angeles area, grandson
of an Italian immigrant who took young Mike on his mushroom-collecting
expeditions. “I always enjoyed playing with dirt,” he says, smiling,
“but I didn’t know I’d go into it for a living.|
He was a prelaw freshman at Berkeley in 1973 when soil science
changed his life. “I needed a science class, and I heard this one was
easy. When I walked out of class the first day, I somehow knew what I
wanted to do with my life.” It was an epiphany: “Soil science brought
together biology, geology, chemistry, ecology, climatology. Integrating
so many different perspectives really appealed to me.”
After graduating in soil resource management in 1977 (he was class
valedictorian), he joined the Forest Service as a soil scientist on the
Siskiyou national Forest. He started to notice that the beautiful, bushy
Douglas-fir and other conifer seedlings that came from the nurseries
often didn’t do well when planted out on harvest sites.
He happened to hear a lecture from OSU mycologist Jim Trappe on soil
microorganisms, and it was another “Aha!” moment. “What I was seeing in
the field,” he says, “couldn’t be explained by soil physical properties
or plant nutrients alone.” In his agronomically focused soil program at
Berkeley, “we got only a tidbit of information on soil microorganisms.
All our textbook photos of roots were nonmycorrhizal, something you
never find in nature. Jim’s information on soil biology was fresh and
After earning a master’s in geomorphology at Antioch College, he
went to OSU for a doctorate in soils, studying with now-retired
ecologist Dave Perry. “The best work in the world was happening in
Corvallis, with (OSU professors) Randy Molina, Mike Castellano, Jim
Trappe, Dave Perry, Andy Moldenke, Efren Cazares, Dan Luoma, and a host
of world-renowned visiting scientists,” he says. “OSU was and is the
center for soil biology.” He received his doctorate in 1989.
In 1997, after 20 years with the Forest Service, he decided to break
away and start his own business. He’d found a niche: “There were a lot
of researchers on fungi,” he says, “but not many were doing applied work
in a scientific way.”
The science of mycorrhizae is not new. “There are some 40,000 papers
out there. But what’s lacking has been the practical focus. How to use
this knowledge to help real people with real problems? Bridging that gap
is what we’re about.”
Ever a scientist, Amaranthus emphasizes research and monitoring. He
encourages clients (nine of 10 are repeat customers) to conduct
comparative studies and report results back to the company.
Amaranthus keeps up his scholarly work, regularly publishing his
research and giving lectures and presentations. He holds a courtesy
appointment as associate professor in the OSU Department of Forest
Mycorrhizal Applications has five full-time employees and a seasonal
crew. In 1998 the company sold enough mycorrhizal products to inoculate
200 million plants. Amaranthus hopes to double that figure in 2000, but
he’s being careful not to move too fast. “I don’t want to lose the
hands-on aspect,” he says. “I want to keep on being the science guy.”



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