An ecosystem is a community of living and non-living things, and ecosystems can be as large as a desert or as small as a tree. All components of an ecosystem work together to make it balanced -- every living species has a specific purpose, or niche, to keep the ecosystem healthy, and light from the sun, nutrients in the soil and supply of water keep those species alive and working. Only through the combination of living, or biotic factors, and non-living, or abiotic factors, an ecosystem can survive.

Biotic Components: The Living

Biotic components of an ecosystem are the living things, which include plants, animals and microbes. Biological communities of living things form groups of organisms that have similar "jobs" or functions within that ecosystem. For example, photosynthetic plants form a group, and plant-eating animals form a group called herbivores, a term which describes their function in the larger picture. These groups are used to describe the food chain, in which energy from the sun is transformed throughout the ecosystem. The sun’s energy is captured by plants, called primary producers. Herbivores, called primary consumers, eat plants, and carnivorous secondary consumers eat the primary consumers. Decomposers like bacteria and fungi consume waste and living things that have died.

Abiotic Components: The Non-Living

Biotic factors in an ecosystem cannot survive without abiotic components, which include light, temperature, water, atmosphere and soil. In nearly all ecosystems, sunlight is the abiotic component that the rest of the ecosystem depends on, as it is the major source of energy. Temperature also affects both plant and animal life; for example, some animals hibernate during cold months, and other animals migrate seasonally.

Interactions in an Ecosystem: Balancing the Scale

The biotic and abiotic components in an ecosystem provide equilibrium, much like you would see in a balance scale; if one side is too heavy, it throws the scale out of balance. For example, the amount of a nonrenewable resource, such as space, affects the population of a given species. The carrying capacity is the maximum number of organisms that the ecosystem can support, which is usually determined by the amount of renewable and nonrenewable resources. Some species compete for space and resources, and other species have predator-prey relationships with each other, making one species a resource for another.

Energy and Element Processes in an Ecosystem: Keeping it Going

Sunlight is the primary source of energy in an ecosystem. Through photosynthesis and respiration, sunlight becomes organic molecules, so light energy becomes chemical energy. This energy is eventually converted into heat, which dissipates and cannot be recycled; this result is why continuous light from the sun is necessary. Elements also pass through the ecosystem; plants obtain them through abiotic components like soil or water, and animals obtain them through the process of consuming plants and other animals. Once decomposers do their “job,” elements are cycled back into the ecosystem.