Explain why producers are always the first tropic level in a food chain or web?

Producers are not always the first trophic level in a food chain or web. In some cases, decomposers may be the first trophic level, as they break down dead organisms and release nutrients back into the environment. These nutrients can then be used by plants, which are consumed by herbivores, which are in turn consumed by carnivores. In this case, the decomposers would be the first trophic level, followed by the plants, herbivores, and carnivores.