Abiotic Factors

Definition

Ecosystems are affected by abiotic factors, also known as abiotic components. Abiotic factors are part of the ecosystem and can affect the associated living things, but they are not living. “Abiotic” comes from the root parts “a-” meaning “without,” and “bio,” meaning “life.” “Biotic factors” are the living parts of an ecosystem.

Examples of Abiotic Factors

Common examples of abiotic factors include:

• It’s windy
• The rain
• Temperature and humidity
• The latitude
• The temperature
• The elevation
• A description of the soil composition
• The concentration of salt in water is known as salinity
• The radiation
• Environmental pollution

Abiotic factors make up much of the variation seen between different ecosystems. By determining the availability of essential resources such as sunlight, water, oxygen, and minerals, abiotic factors influence which organisms can survive in a given place.

The following are a few examples of how abiotic factors can shape ecosystems by determining which organisms can live in them, and what those organisms must do to survive.

In many places, prairie or savannah ecosystems evolve instead of forest or jungle ecosystems, for example, because there is not enough rain to support trees. Other factors, such as high winds and soil that is poor in essential nutrients, may also help to create an environment in which trees cannot survive but prairie plants are prevalent.

Abiotic factors may also include added challenges to life forms, such as temperature extremes, high winds, or even pollution. Human activity has also become an important factor in determining which life forms survive in some ecosystems.

Desert Abiotic Factors

Perhaps the most obvious biome that is determined by abiotic factors is the desert. Because of low rainfall, deserts develop ecosystems that are highly distinct from those of any other habitat.

Scientists use the term “desert” to refer to any area which has less than 25 cm, or 9.75 inches, of rain or snow in an average year. By this definition, deserts cover about 20% of Earth’s land area, including the continent of Antarctica.

Desert ecosystems can also experience extreme temperature swings because open water and water vapor act as temperature stabilizing elements in wetter biomes.

Between the low rainfall and the often extreme temperatures, deserts develop unique organisms and food chains.

Tropical Rainforest Abiotic Factors

At the other end of the spectrum, tropical rainforests are one of the wettest ecosystems on Earth. To be classified as a rainforest, an area must receive at least 75 inches (190 cm) of rain per year. Most rainforests get well over 100 inches (254 cm) annually.

Tropical rainforests are rainforests located in the tropics. The tropics form a belt around the equator and receive a great deal of sunlight throughout the year, resulting in warm temperatures and mild seasons.

Due to their warm and wet climates, rainforests develop extremely dense, lush, and complex ecosystems. Rainforests are unique in that they consist of life layered on top of life. Most scientists divide tropical rainforests into six different layers, each of which hosts different types of life!

The topmost layer of the rainforest – the “canopy” – receives the most sunlight, while the bottom-most layers receive very little sunlight because of shade from plants in the other layers. This impacts the species that are able to grow in these layers.

Tundra Abiotic Factors

Another unique type of biome created by abiotic factors is the tundra.

Tundras are located in the north polar region, where they receive very little light and heat from the sun. As a result, only a thin, top layer of soil thaws sufficiently to allow plant growth. A deep layer of soil, called subsoil, can remain frozen for thousands of years.

Because the subsoil remains frozen, trees (which require deep roots) cannot grow in the tundra. Instead, grasses and other small plants that can grow in the thin soil flourish.

Abiotic Factors in the Ocean

The ocean hosts some unique abiotic factors. Notably, the ocean contains salt. It also has the attribute of depth, which affects the amount of sunlight that sea life receives.

The saltiness of the ocean is important for the animals living there. All creatures must adapt to prevent the ocean’s salt from disrupting their biochemistry. Dolphins that swim in the ocean get all of their water from their prey animals because the saltwater would dehydrate them. Some fish can survive only in saltwater because they have adapted so well to the environment.

The ocean, like the rainforest, also has a number of different zones that receive different amounts of sunlight and host very different types of life. This is because water itself both blocks out and absorbs sunlight.

Life in the topmost zone of the ocean, called the epipelagic zone, receives a large amount of sunlight. This is where photosynthetic ocean life, like coral and seaweed, is found.

By contrast, the abyssopelagic zone at the bottom of the ocean receives almost no sunlight. This part of the ocean hosts strange sea creatures, some of which cannot survive at the surface because their body structures depend on the high water pressure at depth.

The very deep trenches of the ocean contain an even colder, darker zone called the “hadopelagic.” This zone is named after the Greek underworld.

As a result of these abiotic factors, there are different ocean ecosystems, such as shoreline ecosystems, coral reef ecosystems, and deep ocean ecosystems.

Abiotic Factors in Other Ecosystems

There are many other ecosystems impacted by abiotic factors besides those described above. Earth’s surface is covered by ecosystems, and abiotic factors impact all living things within them. The following ecosystems are also shaped by abiotic factors:

• Climates in temperate rainforests, sometimes called temperate broad-leaved forests, are mild and seasonal. Although they are less dense than tropical rainforests due to milder weather, they still contain a variety of biomes.
• Rivers, ponds, lakes, springs, and wetlands are all examples of freshwater ecosystems. Temperature, light penetration, and pH are abiotic factors affecting these ecosystems.
• In contrast to forests, grasslands are primarily dominated by grasses, lacking the abundance of trees needed to qualify as forests. There is too much rainfall to be considered a desert, but not enough to support a forest ecosystem.
• The subarctic taiga ecosystem consists of cold forests. They are characterized by evergreen trees and plants that can survive the cold, such as mosses and mushrooms. Among the animals are moose, bear, deer, and lynx.

Human Activity: Pollution and the Peppered Moth

There were two types of moths in the United Kingdom at the beginning of the 19th century. The white-bodied peppered moth was the most common, which blended in with tree bark to avoid being eaten by birds because of its black-speckled white body.

In the United Kingdom, however, coal-burning factories produced massive amounts of ash, which covered surrounding forests during the Industrial Revolution. The result is that white-bodied moths now stand out against the dark tree trunks, while black-bodied moths, who had been at a disadvantage against the pale tree bark, are now able to hide better.

Naturalists studying peppered moths found that black-bodied moths were dominant near factories, while white-bodied moths remained dominant in soot-free forests in rural areas. Check out this article for more information about this fascinating story.

Abiotic Factors vs Biotic Factors

As opposed to abiotic factors, biotic factors are all the living components that influence an ecosystem. In the environment, biotic factors include organisms and decaying organic matter. Abiotic and biotic factors have different effects on an ecosystem, but both are important. Check out this article that compares biotic and abiotic factors to learn more.

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