An Inconvenient Truth about Fungi?
(there is a general tendency by the majority of biologists to woefully underestimate the role of fungi in the ecosystem)
Based on their roles in building up plant materials through mycorrhizal associations, and destroying their remains through biological decay of cellulose and lignified cellulose etc, the biomass of fungi in forest soils can reach 90% of the total (excluding higher plants) and exceeds all other macro-, meso-, and micro-organisms combined.
The largest active components of the fungi are the assimilative hyphal systems of thousands of species of fungi that permeate the soil and organic debris, live in or on plant plant roots, and/or parasitize a myriad of living things (micro, meso and macro). There are also incredibly large numbers of spores of fungi in soil, as well as yeasts and other unicellular fungi. This means of course that these active fungal components are responsible for most of the respiration in soil. Consequently the bulk of CO2 produced in forest soils is a result of the biological activities of fungi.
Based on the respiration of massive amounts of hyphal material it is clear that fungi are the driving force of the terrestrial Carbon Cycle.
(Diagram from MycoAlbum CD by George Barron)
Regarding agricultural soils, it was reported in New Scientist in December 1982 that scientists at Rothampsted Experiment station in England had developed a new more accurate technique for measuring biomass in a wheatfield soil and estimated a total biomass of five tonnes of living biomass per hectare of which over 50% was fungi (not including yeasts and fungal spores).
For more information on this stuff on this website click here