The main process that drives the flow of energy through an ecosystem is trophic dynamics, which involves the transfer of energy from one trophic level to another via food chains and webs. Energy originates from the sun, captured by producers during photosynthesis. This energy is then transferred to various levels of consumers, including herbivores and carnivores. Decomposers complete the cycle by breaking down organic matter, returning nutrients to the soil and enabling further energy transfer.