A food chain is a series of transmission of food and energy within an ecosystem. In a food chain the food and energy is transferred in the trophic levels. The trophic levels forms the hierarchy of feeding organisms in a food chain.
The producers come in the lowest trophic level. These are the organisms which can synthesize their own food by photosynthesis. They are the source of food and energy for a large diversity of animals and organisms of the other trophic levels.
The loss of plants, or producers from an ecosystem can reduce the population of primary consumers as they includes the herbivores. The decline in population of the primary consumers will reduce the population of secondary consumers which may include the carnivores.
When plants die they become food for the decomposer for example Lettuce, If all the Lettuce in someones field died the decomposer would get its nutriets and make the soil stronger, so if you plant more Lettuce and it survives the Consumer would get to eat the lettuce. Hope this helped! :)
