Lesson 8: Ecosystems


It constitutes the gaseous component of earth that envelops the lithosphere and hydrosphere. The atmosphere is divided into several layers.

  • The lower layer of it is Troposphere. The only part warm enough for us to survive in, is only 12 Km thick. Temperature declines with altitude in the troposphere.
  • The Stratosphere extends from 17 – 48 Km above the earth’s surface. It is 50 Km thick and contains a layer of sulfates, which is important for the formation of rain. It also contains a layer of ozone, which absorbs ultraviolet light known to cause cancer, and without which no life could exist on earth. Aeroplanes fly in this layer as it creates less turbulence and does not have clouds.
  • The next layer is Mesosphere in which temperature decreases with altitude.
  • Above this layer is Thermosphere where ionization of the gases is a major phenomenon.

The lithosphere, hydrosphere and atmosphere comprise the non-living or abiotic component of the biosphere. Ecosystem is a part of it. An ecosystem is a dynamic and complex whole, interacting as an ecological unit. The interactions between the Abiotic aspects of nature and specific living organisms together form ecosystems of various types. Natural resources like air, water, soil and minerals, along with the climate and solar energy, form the non – living or Abiotic part of nature. The biotic or living parts of nature consist of plants or living parts of nature consist of plants and animals, including microbes.

Last modified: Thursday, 29 December 2011, 6:53 AM