Transcript The Role of Fungi in Ecosystems

The Role of Fungi in
Ecosystems
The Role of Fungi in Ecosystems
Without fungi all ecosystems would collapse - they are vital
to the metabolism of most plant life, and vital to the creation
of soil from woody matter.
Fungi are “the grand recyclers of our planet, the
mycomagicians disassembling large organic molecules into
simpler forms, which in turn nourish other members of the
ecological community. Fungi are the interface organisms
between life and death”.
~ Paul Stamets, Mycelium Running
Mycelial networks, which can span thousands of acres in the
one organism, regulate soils by holding them together,
aerating them, and exuding enzymes, acids, and antibiotics.
There are an estimated 1.5 million species of fungi, of which
around 100,000 have been formally recorded and 10,000
are mushrooms.
Mycelium degrades woodchips so
that they can then be digested by
worms and bacteria.
Source: Mycelium Running
Saprophytic Fungi
Saprophytic fungi are decomposers, responsible for breaking down tough wood
lignan and recycling it back to the forest. There are three rough categories of
saphrophytes:
• Primary decomposers: these are fungi like Oyster and Shiitake mushrooms,
primarily breaking down wood and other coarse fibres.
• Secondary decomposers: these are fungi like the common Button mushroom,
which grow from composted material, and in the wild rely upon the actions of
primary decomposers.
• Tertiary decomposers: typically live in the soil made through years of work by
the above decomposers. An example is Panaeolus sphinctrinus.
Without primary decomposers we
would be buried in forest debris!
Tertiary decomposer found in the
south west of W.A.
Source: Wikimedia Commons
Mycorrhizal Fungi
“Myco” means mushroom and “rhizal” means roots.
Mycorrhizal fungi form a beneficial relationship with a plant’s roots, allowing
the plant to access a wider range of minerals and nutrients, and in turn feed
from sugary plant secretions.
Mycorrhizal Fungi have two different growth patterns:
• Endomycorrhizal - these invade the interior root cells of host plants, and
are found in roughly 80% of plant species.
• Ectomycorrhizal - these sheath the plant’s
roots and extend further into the environment,
bringing nutrients back to the host plant, and
conferring anti-fungal traits to the plant. They
often develop fruit bodies (mushrooms) above
ground.
The left-hand plant lacks the
mycorrhizal partnership that
allows the other to thrive.
Source: University of Hawaii
Mycorrhizal fungi benefit most
plant life on the planet.
Source: Plantaglobe
Parasitic Fungi
Parasitic fungi, such as the Honey fungus, can cause great damage to large
tracts of forest, but also create new habitats and soil in the process. Paul
Stamets argues that the outbreak of parasitic fungi in a forest is a symptom of
wider imbalances within the ecosystem, such as acid rain, groundwater pollution,
insect damage, and loss of protective habitat.
Most parasitic fungi are hardly visible to the naked eye, such as Quambalaria
coyrecup, a fungal pathogen killing large numbers of Marris in the South West.
The parasitic Marri Canker is a
cause for great concern in
Western Australia.
Source: Murdoch University
QuickTime™ and a
decompressor
are needed to see this picture.
Mycoremediation
Environmental remediation entails cleaning up toxins such as petrochemicals and
heavy metals from industrial sites, mine sites, and locations where accidents and
spills have occurred. Many mushrooms are excellent at breaking down the
hydrogen-carbon bonds in petrochemicals - a trait that has traditionally been
employed for their role as wood decomposers. “Mycoremediation” uses
mushrooms to break down toxic residues as well as to absorb heavy metals.
Oyster mushrooms used in a
mycoremediation project.
Source: Mycelium Running
These oyster mushrooms were used to
remediate a maintenance yard for trucks, where
the soil was heavily contaminated with diesel (on
par with Exxon Valdez beaches). Four weeks
after inoculating the soil with grain spawn, the
research team visited to find the soil no longer
black and smelly, but light brown and covered
with large mushrooms. The oyster mushrooms
used the hydrocarbons as a food source, and no
petroleum residues were found in the
mushrooms.
Loss of Fungi
Mycologists are concerned about the global loss of fungi diversity, and the
replacement of complex woodland ecosystems with monocultures, large crops of
single species trees or crops.
Because a timber plantation contains trees all of the same age, the cycle of dead
wood and debris on the forest floor is interrupted, and the requirements for fungi
and other species is lost. Whether these fungi can remain dormant in the soil to
assist future forests is unknown.
Fungi is also threatened by the application of fertilisers, herbicides and
fungicides, and some are pointing to the loss of mycorrhizal fungi as a leading
cause for the success of parasitic pathogens such as dieback.
Land-use change erodes the
conditions necessary for fungal
diversity.
Source: Eco Now
Cultivating Mushrooms
Fully colonised bags of straw
rapidly develop fruit bodies.
Source: Swan Valley Gourmet Fungi
Related HotRock Resources
Grow Indoor Mushrooms
Mushrooms have been in the human diet for thousands of years, and in some
cultures have been cultivated for hundreds of years. Shiitakes have been grown
on logs in Japan for 1000 years, and button mushrooms were being
cultivated in the caves of France in the 1800s. These days most
mushrooms are grown indoors in controlled environments.
QuickTime™ and a
decompressor
are needed to see this picture.
HotRock has developed a resource in the Knowledge Bank section
of our website on growing indoor mushrooms.
Oyster mushrooms can be grown
from bags of Rye grain inoculated
with spawn.
Source: Greenbank Mushrooms
Human Impact on Ecosystems
Loss of fungi is only one aspect of the environmental degradation
caused by people. More information on the impact of humans on
ecosystems can be found in the Knowledge Bank in the resource
“Human Impact on Ecosystems”.
References
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Plantaglobe - Mycorrhizal Technology
http://www.agroforestry.net/overstory/overstory86.html
http://ecologynow.wordpress.com/2011/10/06/the-wound-that-timbercorpsbluegum-plantations-left-behind/
Wallenstein, M. et al. 2005. Nitrogen fertilization decreases forest soil fungal and
bacterial biomass in three long-term experiments. In Forest Ecology and
Management, 222 (2006).
Stamets, P. 2005. Mycelium Running: How Mushrooms Can Help Save the
World. Berkley: Ten Speed Press.
Paap, T., McComb, J., Shearer, B., Burgess, T., & G. Hardy. Canker disease of
Marri (Corymbia calophylla) in the south west of Western Australia. Murdoch
University.
http://www.botany.hawaii.edu/faculty/wong/BOT135/Lect26.htm