1.2. 4: Flows and Storages
Both energy and matter flows (inputs and outputs) through ecosystems but at times is also stored (stock) within the ecosystem:
The Biogeochemical Cycle illustrates the general flows in an ecosystem.
Energy flows from one compartment to another. E.g. a food chain. But when one organism eats another organism the energy that moves between them is in the form of stored chemical energy: Flesh
Energy Flows through an ecosystems in the form of carbon–carbon bonds within organic compounds. These bonds ae broken during respiration when carbon joins with oxygen to produce carbon dioxide. Respiration releases enrgy that is either used by organisms (life processes) or is lost as heat.
The origin of all the energy in an ecosystem is the sun and the fate of the energy is eventually to be released as heat
In the diagram above the flow of energy is shown by the red arrows.
Unlike energy MATTER cycles through the system as minerals (blue arrows). Plants absorb mineral nutrients from the soil. These nutrients are combined in to cells. Consumers eat plants and other consumers egest the minerals they contain and re-combining them in cells. Eventually decomposers break down dead organic matter (DOM) and then return the minerals to the soil. These minerals may betaken out of the soil quickly by plants or can eventually through geological processes become locked within rocks until erosion eventually returns them to new soil.
The geochemical cycles illustrate the flows and storage of energy and matter: The carbon cycle shows the flow of both where as the other geochemical cycles e.g. nitrogen only show the flow and storage of matter.
In both cases though the direction of the flow - producer to consumer, and the magnitude - loss of material up a food chain, amount of carbon dioxide moving from respiration and combustion to the atmosphere, can be described.
