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To: Volsi Mimir who wrote (331)	11/29/2000 11:14:16 PM
From: Volsi Mimir	Respond to of 480

Largest Living Thing Is a 2,200-Acre Fungus in Oregon newhousenews.com A fungus that is the largest living thing ever found has been discovered in the Blue Mountains of eastern Oregon near Prairie City. The fungus, Armillaria ostoyae, covers 2,200 acres in the Malheur National Forest and is estimated to be 2,400 years old, said Catherine Parks, a scientist with the U.S. Forest Service's Pacific Northwest Research Station. Parks led the research, in cooperation with Oregon State University. The fungus, technically a clone because it spreads from a single individual, is nearly half again as large as the previous record holder, an Armillaria ostoyae found in 1992 that covers 1,500 acres near the southern foothills of Mount Adams in Washington state. The massive organism, a root-rot fungus that causes wood decay, stunts growth and sometimes kills trees, grows underground over an area equivalent to nearly 31/2 square miles. Despite its size, few people are likely to have seen the fungus. If you pull up the bark at the base of an infected tree, right underneath you will see a white mycelium felt, which peels back like latex paint," Parks said. "It is all matted and thick." The fungus spreads underground through the upper soil, using black, shoestring-like survival structures called rhizomorphs that grow as long as 10 feet. When they contact a tree root, the rhizomorphs penetrate it by a combination of mechanical pressure and enzyme action. Armillaria ostoyae produces clusters of golden-brown mushrooms, but they are rarely seen in eastern Oregon because of the climate. The lack of mushroom production helps explain why such a big fungus is found there. The spores released by mushrooms are the product of sexual reproduction and therefore grow into genetically different individuals, rather than identical clones. Because so few mushrooms are produced, new, genetically different Armillaria ostoyae individuals are rare. The original clone thus has the habitat all to itself and can continue to expand via the rhizomorphs. How do scientists know that it's all the same organism, not many similar organisms? "We did DNA fingerprinting and vegetative pairings," Parks said. In vegetative pairings, scientists take samples from different sites and grow them together on a petri plate. If the two samples grow together seamlessly, they are considered to be the same organism. If they form a barrier line on the petri plate, the researchers know they're genetically different. "It is all the same organism," Parks said. "It came from vegetative growth and spreading of rhizomorphs. Also, it can grow on trees without killing them. It has all kinds of pretty incredible strategies." Forest Service officials are not particularly worried about the spread of the fungus, but they take it into consideration when planning management strategies. When doing thinning, for example, the agency might have the logging contractor target the susceptible species. Armillaria is the most common root disease in Oregon, but it can be found around the world, said Greg Filip, an associate professor at OSU who collaborated on the project. "There is a long history of research on Armillaria because of its economic impact." The fungus degrades all the major wood components of a tree simultaneously, progressively weakening it. "It's not a good thing if you want to make 2-by-4's," Parks said. Because the fungus spreads slowly and doesn't affect every tree in the same way, the economic impact is subtle. "It is hard to put numbers on what it does, but it definitely contributes to lack of forest-product productivity," Filip said. But the fungus also plays an important natural role in the forest ecosystem, Filip and Parks said. Armillaria helps wood decay, and dead trees create habitat for wildlife and contribute to nutrient recycling.