The biosphere is a relatively narrow layer around the Earth’s surface where life can exist. It extends from a few kilometers in the atmosphere to the depth of the oceans. It is also referred to as the “Zone of Life”, comprising the atmosphere (air), hydrosphere (water), and lithosphere (land). The energy required to support life on earth comes from the sun in the form of solar energy which producers like green plants capture to produce food through photosynthesis.
Origin of Biosphere
The term “biosphere” was coined in 1875 by a geologist named Eduard Suess. He defined the biosphere as “the place on the earth where life dwells”.
The earliest evidence of life on the earth was found about 3.5 billion years ago. The earliest life forms included prokaryotes. They were single-celled organisms like bacteria that survived without oxygen.
Some of these prokaryotes were able to use sunlight to make sugar and oxygen from water and carbon dioxide, a process that came to be known as photosynthesis. By the process of photosynthesis, these organisms were able to change the structure of the biosphere completely.
Over a long time, the atmosphere of the Earth developed oxygen and other gases that could support life. By this addition of oxygen to the biosphere, more complex life forms were evolved which included millions of different plants (producers) and animals (consumers and decomposers) species. Thus the biosphere developed a food web that helps in sustaining life on the earth.
The remains of dead plants and animals release nutrients into the soil and ocean. These nutrients are reabsorbed by growing plants. This exchange of energy and food makes the biosphere a self-regulating and self-supporting system.
Characteristics
The biosphere is unique as so far, the existence of life has not been found elsewhere in the universe. It is characterized by continuous cycles of matter which is continuously recycled for continuing life on earth.
The biosphere can be thought of as one large ecosystem—a complex community of living beings and nonliving things functioning as a single unit. It comprises biotic (living) and abiotic (non-living) components which continuously interact with each other.
More often, however, the biosphere is described as having many ecosystems.
It measures about 20 kilometers from top to bottom, and almost all life exists between about 500 meters below the ocean’s surface to about 6 kilometers above sea level.
Since life exists on the ground, air, and water, the biosphere overlaps all three spheres vis-à-vis lithosphere, atmosphere, and hydrosphere.
Importance
The biosphere has great importance for all living beings and is termed the zone of life” on the earth. It is the layer around the Earth where life exists. It supports life on the Earth by providing shelter and food etc. to all living beings.
It helps in preserving biodiversity on the planet Earth.
It allows the interaction between different life forms and the environment or between biotic and abiotic components. It is self-regulating. It plays an important role in maintaining ecological balance on the earth.
References
NCERT Biology
IGNOU Material
Shankar IAS Environment book
Recitals Magazine