The biosphere is part of the earth in which life exists. It is 20 km thick from the bottom of the ocean to the lower atmosphere. It consists of three layers: the lithosphere, which is the land on the surface of the earth; the hydrosphere, which comprises of the water on the earth as well as water vapor in the air; and the atmosphere, which is made up of the air that surrounds the earth. The living organisms in the biosphere interact and affect each other in many ways. This is called a biotic factor. Similarly, there are non-living elements that have an effect on living organisms, these are considered abiotic factors. Examples of abiotic factors are air, temperature, water, soil, light, and minerals.
In a biosphere, organisms live in special groupings. For instance, a population consists of all individuals of a species living in a general area. A community is a population located
Changes in an ecosystem are brought about by different factors. For example, ecological succession brings about the replacement of one community by another in an ecosystem. In other instances, organisms that colonize an area with no community present are considered pioneer organisms. A climax community is the final stage of development of organisms and can be disrupted by a major catastrophe like a volcanic eruption.
in a certain area living among different species. An ecosystem is yet a larger conglomeration of a population, a community, and abiotic factors. Ecosystems can be aquatic or terrestrial. The earth's aquatic ecosystem makes up about 75% of the earth's surface. This aquatic environment is divided into marine and freshwater environments. The earth's terrestrial ecosystem is mainly made up of forests and deserts, which make up for 25% of the earth's surface.
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