The primary function of decomposers in an ecosystem is to recycle nutrients back into the ecosystem. Decomposers, which include bacteria, fungi, and other microorganisms, break down dead organic material, such as dead plants and animals, as well as waste products. This process leads to the release of essential nutrients like nitrogen, phosphorus, and potassium back into the soil, making them available for uptake by plants.
This nutrient cycling is vital for ecosystem health, as it ensures that the nutrients are not lost from the system and can continuously support the growth of producers, which are the foundation of food webs. By breaking down complex organic materials, decomposers facilitate the transformation of these materials into simpler forms that can be assimilated by autotrophs.
The other options pertain to different aspects of ecosystem dynamics. Competing with primary consumers, producing organic matter through photosynthesis, and enhancing the growth of producers are not the primary roles of decomposers, but rather relate to the functions of other organisms within the ecosystem.