Dependent on Fungus?

We are all aware of fungus that depends on trees and plants to live.  Many types of fungus live off decaying plant matter and are helpful to the environment by breaking it down.

Shelf fungus on stump

But did you know that many tree and plant species can be aided by fungi when alive?  Mycorrhizal fungi are fungi that establish a symbiotic relationship with the roots of a vascular plant.  

A mycorrhizal fungus that has colonized the roots of  plant
(illustration by Melissa Buntin at Fine Gardening)

A fungus will colonize the plant's roots and send out filaments, called hyphae, as much as 200 times farther into the soil.  With such a large surface area, the fungus is better able to glean water and nutrients from the area, which it sends back to the plant roots.  In return, the plant will give the fungus necessary glucose.

Fruiting bodies of the fungus Amanita muscaria, which lives in a symbiotic relationship with several different kinds of trees  (photo source - Wikipedia)

I had previously heard about orchids having a symbiotic relationship with fungi, but when delving further, mycorrhizal fungi are able to help an astounding number of trees and plants - about 80% of all species, in fact.  Due to this symbiotic fungi, trees and plants are better able to resist drought and disease.

This type of fungi are also especially important for trees that are in areas with poor soil, such as most rainforests, as they help collect nutrients for the trees.  According to the Rainforest Conservation Fund, up to 90% of tree roots in the rainforest are colonized by mychorrhizal fungi.   The fungi even interconnect trees through their hyphae, creating a network or 'fungal mat'.  This may mean that rainforest trees with a higher canopy that can reach more light can transfer needed carbon to the shorter trees that are below in the shade.

A network that interconnects the trees and transfers energy?  Sounds like these fungi are from the Avatar planet of Pandora...
source of photo

Different types of fungus help different types of plants.  Some are very specific, while others will colonize the roots of several different types of plants.

You can buy some mycorrhizal fungus for your very own!  Pictured is a mix of several different kinds of mycorrhizal fungi that help roses, sold by David Austin Roses.

I always wondered why articles about soil amending advise not to till your soil very much, but instead just lay organic matter on top of it.  One of the reasons is that tilling destroys a lot of this type of beneficial fungi.  I, on the other hand, have compacted clay soil in much of my yard which does not provide enough oxygen content for a thriving colony of beneficial fungi - so I'm thinking some tilling may be necessary..

Wanted:  Fungi!
(photo of red clay at Wikipedia)

Previously, the thought of having soil that was teeming with fungus might have been distressing - now that I know all about the benefits of mycorrhizal fungi, however, they are welcome at the Red House garden!

Hostile fungi, on the other hand, need not apply...

The parasitic fungus Armillaria solidipes attacks tree sapwood.  One specimen found in the Malheur National Forest in Oregon covers an area of 3.4 square miles and is one of the largest living organisms in the world.  Most of it is underground - one only sees the evidence of this fungus in autumn when it blooms these little 'honey mushrooms' as pictured.

I am actually linking up to the Word for Wednesday meme over at the wonderful blog of Garden Walk, Garden Talk, my word for Wednesday being 'dependent'.  I am a little late to the party - I am away from the Red House for the week, and my computer apparently gets homesick and does not feel like being cooperative...