What are the main differences between the consumer and the reduction systems?

Energy can go through a community in different ways. It is the food chain of all consumers (the consumer system) with the addition of two more links: it is dead organic matter and the food chain of decomposing organisms (the reducing system).
The flow of energy from plants through herbivorous animals (they are called grazing) is called a pasture food chain.
The residues of the organisms consumed by them that are not used by consumers replenish dead organic matter. It consists of feces containing part of undigested food, as well as corpses of animals, the remains of vegetation (leaves, branches, algae) and is called detritus.
The flow of energy originating from dead organic matter and passing through the decomposer system is called the detrital food chain.
Along with the similarities, there is a profound difference in the functioning of pasture and detrital food chains. It consists in the fact that in the consumer system, feces and dead organisms are lost, but in the reduction system they are not.
Sooner or later, the energy contained in the dead organic matter will be fully utilized by the decomposers and dissipated in the form of heat during breathing, even if for this she needs to go through the system of reducers several times. The only exceptions are those cases where local abiotic conditions are very unfavorable for the decomposition process (high humidity, permafrost). In these cases, deposits of incompletely processed highly energy-intensive substances accumulate, which, with time and under appropriate conditions, turn into combustible organic minerals – oil, coal, peat.