Friday Fungus: Squatting on Planet Mushroom

Us humans think the planet we live on is ours. A plaything gifted to us by gods filled with good things for us to use. We've colonised much of Earth, built great cities, roads, walls, canals - the world is shaped by humanity. We dominate. Or that's what we believe.

Think again. We're squatters on Planet Mushroom:

Fungi are present almost everywhere, in a spectacular array of shapes, sizes and colours, and performing a wide variety of different activities. In 1991 David Hawksworth, a mycologist at Kew estimated the world's fungal diversity at 1.5 million species (equal to the estimated number of all known other living organisms). This was thought at the time to be a radical over estimate, but now other researchers have proposed figures in excess of 13 million. Fungi perform essential roles in every terrestrial, and many aquatic, ecosystems, eg. decomposing dead organic matter to release nutrients, supporting plant life on poor soils by improving the absorption of nutrients when they form mycorrhizal associations with roots, living inside plants as endophytes and forming symbiotic partnerships with algae to form lichens. Any deterioration in fungal populations and diversity can therefore have a considerable impact on ecosystem health, in fact, the loss of lichens from an area is often used as an indication of poor air quality.

We wouldn't be here - there'd be no life - if it weren't for fungi. Plants and animals depend on fungi - without mycorrhizal symbiosis many of our tree species would die. The forests, the grass steppes and even our gardens are grown atop a network of mycelium. The grandest example of this mushroom world is Oregon's honey mushroom:

Next time you purchase white button mushrooms at the grocery store, just remember, they may be cute and bite-size but they have a relative out west that occupies some 2,384 acres (965 hectares) of soil in Oregon's Blue Mountains. Put another way, this humongous fungus would encompass 1,665 football fields, or nearly four square miles (10 square kilometers) of turf.

The discovery of this giant Armillaria ostoyae in 1998 heralded a new record holder for the title of the world's largest known organism, believed by most to be the 110-foot- (33.5-meter-) long, 200-ton blue whale. Based on its current growth rate, the fungus is estimated to be 2,400 years old but could be as ancient as 8,650 years, which would earn it a place among the oldest living organisms as well.

We have a pretty negative relationship with our mushroom masters - they cause disease, they rot things, they poison us and are a symbol of dark, unpleasant places. If you set a google alert for fungi, you'll get a pile of stories about fungal infections complete with gory detail and hard-to-look-at pictures. Plus stories about how bats, frogs and bananas are heading for extinction - destroyed by fungi.

But then without fungi there's no bread and no beer, no blue cheese and your salami rots. Wherever we look, inside and outside, there are members of the fungal kingdom - molds, lichens, yeasts and mushrooms. They are the dominant and most significant lifeform on the planet, they clean stuff up, cure illness and keep plants alive. They even help store carbon:

"Natural fluxes of carbon between the land and atmosphere are enormous and play a crucial role in regulating the concentration of carbon dioxide in the atmosphere and, in turn, Earth's climate," said Colin Averill, lead author on the study and graduate student in the College of Natural Sciences at UT Austin. "This analysis clearly establishes that the different types of symbiotic fungi that colonize plant roots exert major control on the global carbon cycle, which has not been fully appreciated or demonstrated until now."

We truly are living in a world filled with fungi yet we know so little about them and treat the presence of this great kingdom as something to be fought against rather than something to be understood. Sadly there are no undergraduate courses in mycology and precious few postgraduate courses (mostly medical mycology - pretty damned important given the issues with antibiotics). With the result that we're literally running out of mycologists.

Here we are squatting on Planet Mushroom and we know next to nothing about our kindly hosts!

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