Decomposition is crucial to the cycling of elements, such as carbon from one living organism to another. You can learn more about the carbon and water cycles here.
The rate of decay is the speed at which dead matter is broken down by decomposers. The rate can be estimated by measuring changes in pH, for example in milk , change in mass decaying fruit and vegetables or change in temperature grass cuttings. Rates of decay are affected by a number of key factors. At colder temperatures decomposing organisms will be less active, thus the rate of decomposition remains low.
This is why we keep food in a fridge. As the temperature increases, decomposers become more active and the rate increases. At extremely high temperatures decomposers will be killed and decomposition will stop. In dry periods or dry climates, the organic matter becomes dessicated. Many detritivores, such as fungi and slugs, are inactive so the decomposition process becomes prolonged.
In contrast to the softer tissues of herbaceous plants, the fibres of trees and other woody plants are much tougher and take a longer time to break down. Fungi are still, for the most part, the first agents of decay, and there are many species that grow in dead wood.
The common names of species such as the wet rot fungus and the jelly rot fungus indicate their role in helping wood to decompose. The growth of the fungal hyphae within the wood helps other detritivores, such as bacteria and beetle larvae, to gain access. The fungi feed on the cellulose and lignin, converting those into their softer tissues. These in turn begin to decompose when the fungal fruiting bodies die. Many species of slime mould also grow inside dead logs and play a role in decomposition.
Like fungi, they are generally only visible when they are ready to reproduce and their fruiting bodies appear. Some decomposers are highly-specialised. For example, the earpick fungus grows out of decaying Scots pine cones that are partially or wholly buried in the soil. Another fungus known as Cyclaneusma minus grows on the fallen needles of Scots pine.
As the wood becomes more penetrated and open, through, for example, the galleries produced by beetle larvae, it becomes wetter. Being wet facilitates the next phase of decomposition.
Invertebrates such as woodlice and millipedes feed on the decaying wood. Predators and parasites , such as robber flies and ichneumon wasps, will also arrive, to feed on beetles and other invertebrates. For trees such as birch the wood becomes very wet and rotten, and falls apart quite easily after a few years. Earthworms and springtails are often seen at this stage, when the decomposing wood will soon become assimilated into the soil.
They can reach high densities — there can be 1 tonne or earthworms in a single hectare of broadleaved European forest! The wood of Scots pine, however, has a high resin content. This makes it much more resistant to decay, and it can take several decades for a pine log to decompose fully.
Most fungi are soft-bodied and having a high water content. This means they often disintegrate and disappear within a few days or weeks of fruiting. The tougher, more woody fungi, such as the tinder fungus , can persist for several years.
Even so, they often have specialist decomposers at work on them. The tinder fungus, for example, is the host for the larvae of the black tinder fungus beetle and the forked fungus beetle. These feed on the fungal fruiting body, helping to break down its woody structure. Another bracket fungus that grows on dead birch trees, is the birch polypore.
The bolete mould fungus is another species that grows on fungi, in this case members of the bolete group. Boletes have pores on the underside of their caps and include edible species such as the cep. The silky piggyback fungus and the powdery piggyback fungus fruit on the caps of brittlegill fungi. They speed up the process of breakdown and decay in them. Slime moulds, although not fungi, are somewhat fungus-like when they are in the fruiting stage of their life cycle.
The fruiting bodies of a species called Trichia decipiens are susceptible to fungal mould growing on them. This in turn accelerates their decomposition. The vast majority of the decomposers in this case are other animals and bacteria. Animal decomposers include scavengers and carrion feeders.
These consume parts of an animal carcass, using it as an energy source. They also convert it into the tissues of their own bodies and the dung they excrete. These animals range from foxes and badgers to birds such as the hooded crow. They also include invertebrates such as carrion flies, blow-flies and various beetles. Their dung in turn is eaten by other organisms, particularly dung beetles and burying beetles.
Some fungi, including the dung roundhead grow out of dung, helping to break it down. Not all animal carcasses are immediately consumed by large scavengers. In these cases there are five main stages in the decomposition process. The first of these is when the corpse is still fresh. At this stage carrion flies and blow-flies arrive and lay their eggs around the openings, such as the nose, mouth and ears.
In the second stage, the action of bacteria inside the corpse causes putrefaction. Learn about community patterns and the ecological factors influencing these patterns. Revisit some of the ecosystems you've learned about earlier to learn more about the possible impacts of natural and human-induced environmental changes Skip to content Main Navigation Search. Dictionary Articles Tutorials Biology Forum.
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