How to describe the fungi and their roles in the environment?

Fungi play three major roles in the environment:
 
1) Decomposition - fungi are able to break down almost anything - furthermore they can pair with algae to make lichens - which grow almost anywhere - lichens are also an important indicator of environmental pollution.

2) Mycorrhizal partners - fungi are mycorrhizal partners in trees and plants. Root hairs in trees and plants are often not fine enough to absorb nutrients from the soil by themselves. Mycorrhizal fungi often form a symbiotic partnership with plants and trees - fungi provide thin hyphae (unicellular root like structures) that can absorb water and nutrients from the soil more efficiently than root hairs. The trees and plants in turn provide food (complex amino acids etc) for the fungi - things that they would normally not be able to obtain. It is proposed that 90% of all the species of trees and plants are dependent on mycorrhizae. There are 2 types of mycorrhizae - endotrophic and ectotrophic - but thats for another topic of discussion.

3) Fungi are also parasites - they live on trees in forests. This is why you find many mushrooms in forests. Basidiomycetes (the class of true mushrooms) are excellent decomposers.

Negative aspects of fungi

- rotting - a specific type of rotting is the dry rot - which basically sucks everything out of the material it is rotting till its like a fine white powder. rotting is bad for buildings and such. Also fungi spores (fungi reproduces by spores either asexually or sexually) can be inhaled and could possibly be a problem for people susceptible to asthma.
Some fungi are poisonous - ex: the death cap mushroom - aminita. Amanita toxins are the most lethal in the world shutting down RNA synthesis in the body. Other mushrooms such as the false morrel - pose as good mushrooms (morrels you can eat) but are full of deadly poisons.

In conclusion, fungi have many many positive roles and a few notable negative roles.

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