can neither be created nor destroyed, only converted in form.

This means that the only way material stuff (e.g., ) can leave an ecosystem is by physically leaving an ecosystem. As a consequence, the either produced by organisms or that makes up their bodies, including following tends to remain within ecosystems, or at least the as a whole.

In addition to physically leaving ecosystems, materials also can enter into ecosystems. This movement between ecosystems typically occurs either in a form, in the course of , or as organisms move from location to location.

Lastly, numerous organisms are capable of converting elements that otherwise are bound up within organisms into a , indeed forms, where it then becomes available to other organisms.

All of these ideas form the basis of biogeochemical cycles as well as ecosystem ecology generally. They involve, to a substantial extent, various trophic interactions between organisms, including in terms of the action of detrivores and decomposers.