The Living (biotic) and Nonliving (abiotic) Features of an Ecosystem

Unlike a biological community made up of only living organisms, ecosystems include both living organisms (biotic factors) and non-living(abiotic factors) that occur in a specific area. This includes the physical and chemical factors that make up the environment.

Abiotic and Biotic Components in an Ecosystem

Abiotic Factors	Biotic Factors
Sunlight	Photosynthetic Organisms (i.e. Primary producers)
Temperature	Herbivores
Precipitation	Carnivores
Water or Humidity	Omnivores
Dry Soil or water chemistry (e.g., Phosphorous, CO2)	Decomposers

Every biotic organism depends on interactions with abiotic factors. Source: Wikimedia Commons. By: Doron License: Creative Commons Attribution Sharealike 3.0

What does an interaction between abiotic and biotic factors look like?

Part of what sustains an ecosystem is the constant exchange of energy and matter between living organisms (biotic components) and nonliving components (abiotic factors).

In upcoming chapters, you will read more about energy transformations and biogeochemical cycling that take place between biotic and abiotic factors.

One way to demonstrate how abiotic and biotic factors interact is to look at healthy soil. Small minerals (abiotic) collect in soil made of tiny soil animals, plant roots (biotic) and clay, sand, water & air (abiotic). Plants (biotic) use this soil mixture (of abiotic and biotic components) along with water (abiotic) to build stems and leaves and flowers.

Sun, wind and rain

Any ecosystem depends of the presence of abiotic features.

The sun (abiotic) provides energy for plants (biotic) that are changed through photosynthesis into sugars that are eaten by people (biotic).
Wind (abiotic) blows pollen around from some plants (biotic) so they can pollinate.
Water (abiotic) can also move pollen and seeds around (biotic).

Source: Wikipedia By: Mwanner License: Creative Commons Attribution Sharealike Unported 3.0 The following abiotic factors influence which organisms are able to live in a specific ecosystem:

Available sunlight
The temperature range
Levels of precipitation
Humidity
Amount of sunlight
Rocks, mineral, soil and other resources
Types of sedimentary deposits

Without Sunlight, Where does Life on Ocean Floor get Its Energy?

Organisms living around hydrothermal vents (deep sea vents) at the ocean bottom are too deep in the ocean to receive energy from the sun. These organisms get their energy through a process called chemosynthesis that happens in bacteria instead of photosynthesis that takes place in plants.

Hydrothermal vents image - Source: National Oceanic and Atmospheric Administration. License: Public Domain.
Tubeworms image - Source: National Science Foundation By: Nicolle Rager Fuller.

How can Living Organisms (biotic factors) change the Abiotic World?

Wind and rain (two abiotic components) are not the only factors that wear rocks down. Even plant roots, lichens, and miniscule mosses (biotic forms) canturn a huge boulder (anabiotic form) into a pile of dusty-looking minerals.

Moss image - Source: Wikimedia. By: Ivo Shandor. License: Creative Commons Attribution Sharealike 3.0.
Lichen image - Source: Wikipedia By: Roantrum. License: Creative Commons Attribution 2.0.

Plant roots, and tiny lichens andmosses may not seem strong, but they are able to push their way into the miniscule crevices in a rock and gradually push the rock's particles apart. Overtime, the rock is broken down into smaller and smaller bits.