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The major recognizable life zones of the continents are called biomes. Because vegetation is usually the dominant and most apparent feature of the landscape, a biome is characterized by its plant community. More formally, a biome can be defined as a major biological community of plants and animals with similar life forms and environmental conditions. In the Earth system, the biome is the largest biotic geographic unit.
Biomes are named for the dominant type of vegetation they contain, such as grassland or forest. Because they are defined by environmental conditions and vegetation, the same type of biome may be found in different parts of world. For example, desert biomes, are found largely in locations between 15° and 35° latitude North and South of the Equator that receive scant rainfall (less than 10 inches [25 centimeters] per year on average).
The six major biomes are tundra, taiga, temperate deciduous forest, tropical rain forest, grassland and savanna, and desert. (Encyclopedia Britannica Source)
The abiotic environment has three main parts: the atmosphere, the hydrosphere, and the lithosphere. The atmosphere is the air—the shell of nitrogen, oxygen, carbon dioxide, and other gases that surrounds Earth. The hydrosphere includes all of the liquid and frozen waters on Earth’s surface, as well as groundwater held in soil and in rock, and water vapor that is suspended in the air. The lithosphere consists of the outer layer of Earth—the crust and the solid layer of the upper mantle as well as the rocks and soil on Earth’s surface.
The biotic environment consists of the biosphere—the “zone of life” composed of living things as well as their products, remains, and wastes. Thus plants, animals, fungi, algae, protists, bacteria, and other organisms are biotic factors, as are seeds, flowers, fruits, nectars, and honey. Leaf litter, dead grasses, animal wastes, and the remains of dead organisms are part of the biotic environment as well. (Encyclopedia Britannica Source)
A habitat is the place where an organism or a community of organisms lives. A habitat includes all living and nonliving factors or conditions of the surrounding environment. Almost every place on Earth—from the hottest desert to the coldest ice pack—is a habitat for some kinds of living things. Habitats may be geographic locations or the interior of the human intestine. Thus a host organism inhabited by parasites is as much a habitat as a forest or a pond. (Encyclopedia Britannica Source)
An ecosystem consists of all the living and nonliving things that occur together within a particular area. An ecosystem can be small, such as a family garden, or large, such as the Amazon rainforest. It may be terrestrial, such as a grassland, or aquatic, such as a pond or a coral reef. All of the organisms living within an ecosystem rely on each other for their survival.
An ecosystem includes abiotic, or nonliving, components, such as minerals, climate, soil, water, and sunlight. It also includes biotic, or living, elements, such as plants, animals, fungi, protists, and bacteria. The living and nonliving parts of an ecosystem are linked together by two major forces: the flow of energy through the ecosystem and the cycling of nutrients within the ecosystem. (Encyclopedia Britannica Source)
