Write an essay on the role of fungi in wood and litter decay.
Write an essay on the role of fungi in wood and litter decay. [40]
Fungi, together with bacteria, are the principal decomposers in the biosphere. They break down organic materials and return the substances locked in those molecules to circulation in the ecosystem. Fungi can break down cellulose and lignin, an insoluble organic compound that is one of the major constituents of wood. By breaking down such substances, fungi release carbon, nitrogen, and phosphorus from the bodies of living or dead organisms and make them available to other organisms. Wood-decay fungi are a variety of fungi that digest moist wood, causing it to rot. Some species of wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria, are parasitic and colonize living trees. (Raven and Johnson, 2011) Wood decay fungi can be grouped in different ways: according to their mode of attack on the woody cell walls, by their general biology, pathogens, parasites or saprotrophs and whether they are primary or secondary colonisers. Wood-decay fungi can be classified according to the type of decay that they cause. The can be grouped into three distinct groups, that is; soft rot fungi, brown rot fungi, and white rot fungi. (Deacon, 2005)
First group to be considered are the soft-rot fungi. They are the least specialised of the wood-rot fungi. Soft-rot fungi grow on wood in damp environments and also occur in wood of high water content and high nitrogen content. They have a relatively simple mode of attack on wood. They are the characteristic decay fungi of fence posts, telegraph poles and wooden window frames. Soft-rot fungi degrade cellulose and hemicelluloses. They need fixed nitrogen in order to synthesize enzymes, which they obtain either from the wood or from the environment. Their hyphae grow in the lumen of individual woody cells, usually after entering through a ‘pit’ (depression) in the wall. Then they produce fine
Fungi, together with bacteria, are the principal decomposers in the biosphere. They break down organic materials and return the substances locked in those molecules to circulation in the ecosystem. Fungi can break down cellulose and lignin, an insoluble organic compound that is one of the major constituents of wood. By breaking down such substances, fungi release carbon, nitrogen, and phosphorus from the bodies of living or dead organisms and make them available to other organisms. Wood-decay fungi are a variety of fungi that digest moist wood, causing it to rot. Some species of wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria, are parasitic and colonize living trees. (Raven and Johnson, 2011) Wood decay fungi can be grouped in different ways: according to their mode of attack on the woody cell walls, by their general biology, pathogens, parasites or saprotrophs and whether they are primary or secondary colonisers. Wood-decay fungi can be classified according to the type of decay that they cause. The can be grouped into three distinct groups, that is; soft rot fungi, brown rot fungi, and white rot fungi. (Deacon, 2005)
First group to be considered are the soft-rot fungi. They are the least specialised of the wood-rot fungi. Soft-rot fungi grow on wood in damp environments and also occur in wood of high water content and high nitrogen content. They have a relatively simple mode of attack on wood. They are the characteristic decay fungi of fence posts, telegraph poles and wooden window frames. Soft-rot fungi degrade cellulose and hemicelluloses. They need fixed nitrogen in order to synthesize enzymes, which they obtain either from the wood or from the environment. Their hyphae grow in the lumen of individual woody cells, usually after entering through a ‘pit’ (depression) in the wall. Then they produce fine
References: Campbell, N. A. (2011) Biology 9th ed, San Francisco; Pearson Benjamin Cummings. Deacon, J. (2005) Fungal Biology, Edinboro; Blackwell Raven, P. H and Johnson, G. B (2011) Biology 9th ed; New York McGraw Hill Companies Inc. Sharma, O.P. (2005) Textbook of fungi, McGraw-Hill: New Delhi