Green plants are the producers , the base of the food web. Animals that consume plant material are called herbivores . Animals that consume herbivores are called carnivores . Some carnivores eat other carnivores, so there may be several trophic levels in an ecosystem. Predators at the top of the food web are called top carnivores .
Some animals eat plants as well as other animals.
They participate in energy and material flows at several trophic levels within an ecosystem. Of course, at all of these trophic levels, much biomass dies before being consumed by larger animals. E. Material flow through ecosystems. In terrestrial ecosystems, the soil is the main reservoir of usable nutrients. Once nutrients are tied up in biomass, they are not available to other organisms, until they are consumed or released by decomposition.