Something stirs in the forest!

Most of us are aware of Honey Fungus.  This pathogen attacks the roots of many trees and plants. We are loss aware of how extensive the fungal colony can be.  The largest living thing is believed to be a related species. This is Armillaria ostoyae which is sometimes known as Shoestring Rot.

Shoestring Rot is quite common in the forests of Oregon, Washington and British Columbia.  The trees are dying.  Overhead the leaves thin out.  White mycelia grow into the sapwood.  Black rhizomorphs run beneath the bark and between the trees.  The rhiozomorths search out new trees and carry enzymes to commence the rot.  The forest is dying.  On the surface the only evidence is a cluster of autumnal mushrooms at the base of an infected tree.  

Foresters are concerned.  The fungus is causing the death of commercial softwoods, such as Douglas-fir and  Western Hemlock.  In British Columbia some 3.8 million cubic metres of timber is lost each year.  There is little that the foresters can do to prevent its spread.  They resort to grubbing out the infected stumps and replacing the infected trees with more resistant types.  Western redcedar and deciduous trees are more resistant.

Scientists are trying to understand the extent of the infections. They have found that when measured by areal extent the Shoestring Rot can be regarded as one of the largest organisms on earth.

In 1992 scientists discovered that an Armillaria ostoyae colony within Washington state.  This single organism extended over 6 square kilometres (1,500 acres).  

In 1998 scientists began to investigate another Armillaria ostoyae colony. It lies within the Malheur National Forest at the Strawberry Mountains in eastern Oregon.  The extent of the infection was detemrined from aerial photos   It has a radius of 5.6 kilometres (3.5 miles) and extended over 8.9 square kilometre (2,200 acres). It extended to a depth of one metre in the sold.  Genetic tests indicated that a single organism was responsible.  Calculations based upon the known rate of growth for the fungus suggest that the colony is 2,400 years old.  The total biomass could be as much as 605 tons. 

The Strawberry Mountains colony has been intensively studied.  It remains the largest single organism fungal colony that is known.  However, there are rumours that a much larger colony, extending to 11,000 acres, exists somewhere in Washington state.  Confirmation of the rumour would establish Washington state as home to the largest living thing on earth.

If you enjoyed this article take a look at The Quaking Aspens of Utah.  These are another contender for the title  “The Largest Living Thing on Earth”.