Biotic factors are the living things that make up an ecosystem, while abiotic factors are the nonliving elements that affect an ecosystem and the living things that are a part of it. Biotic and abiotic factors interact closely to shape an ecosystem.
There are three main types of biotic factors in an ecosystem: producers, consumers and decomposers. Producers, or autotrophs, are organisms that obtain energy from abiotic factors and use that energy to create food. Plants are a common example of producers. Consumers, or heterotrophs, must consume other biotic components of an ecosystem for food. They may consume producers or other consumers. Decomposers, or detritivores, break down dead biotic factors for food and, as a result, return biological material to the ecosystem. Fungi and some bacteria are detritivores.
Abiotic factors include nonliving components of an ecosystem, such as temperature, humidity and light. Sunlight is an important abiotic factor, as it contributes the initial energy input of an ecosystem. Energy from the sun drives photosynthesis in producers. In ecosystems without sunlight, such as deep ocean regions, gases from hydrothermal vents are important abiotic components for energy. In aquatic ecosystems, the gas content of the water plays a large role in the biotic makeup of the community. Oxygen content determines what consumers thrive in the environment while carbon dioxide concentration affects the producer community.