Final answer:
Decomposers, such as bacteria and fungi, are responsible for cleaning up the remains of dead plants and animals in a forest ecosystem. They break down the organic matter and release nutrients back into the environment.
Step-by-step explanation:
Organisms responsible for cleaning up the remains of dead plants and animals in a forest ecosystem are called decomposers.
Decomposers include bacteria and fungi, such as mushrooms on decaying logs.
They break down the dead organic matter and release simple inorganic molecules back into the environment, which can be used by producers to make new organic compounds.
Without decomposers, the nutrients within the dead organisms would not be released back into the ecosystem, affecting the growth and survival of other organisms.