Basic Global ecosystem and Their Types

 

Global ecology is the study of the interactions among the Earth's ecosystems, land, atmosphere and oceans. Global ecology is very important because it is used to understand large scale interactions and how they influence the behavior of the entire planet, including the earth's responses to future changes.  

There are four types of global ecosystem.

  

Atmosphere 

Major zones and importance multilayers gaseous envelope surrounding the planet earth is referred as atmosphere. The atmosphere remains in contact with all the major types of environment of earth interacting with them and greatly affecting their ability to support the life. It filters sunlight  that reach on the earth  surface affects climate and it is a reservoir of several elements essential for life. Smith (1974) studied the zones of atmosphere.

According to him, the atmosphere surrounding the earth consists of a series of following layers ~r zones viz., 1. Troposphere, 2. Stratosphere,3. Mesosphere, 4. Heterosphere and 5. Exosphere. 

  1.     Troposphere: It is the lowest region of atmosphere which hangs at 8 km over the earth at the poles and nearly 18 km over the earth at the equator. This zone, subject to differential heating temperature, inversion and conversion currents is called troposphere. Temperature drops rapidly from 30° to -70°C in the zone. Troposphere is the region o fstrong air movements and cloud formation. Man along with other living organisms lives in the troposphere.  

2.     Stratosphere: It is 2nd layer of the atmosphere. It is 50 km away from the earth having a fairly constant temperature at - 75°C to - 45°C in its outer region which increases upto 300°C at its lower boundary. Within the stratosphere, ozone (03) accumulates sufficiently to produce a well marked ozone layer called 'ozonosphere' which extend about 13 to 23 km above the sea level. In ozonosphere, the sunlight ionizes oxygen to ozone by photochemical  dissociation. The ozonosphere absorbs solar ultraviolet radiation from the sun and saves the earth  away from the harmful effects of ultraviolet radiation.  

3.     Mesosphere: It is 3rd layer of atmosphere which is 80 km from the surface of earth. This is the region of cold temperature (-90° to -120°C). 

4.     Heterosphere: It is the 4thlayer of the atmosphere. In heterosphere, oxygen and nitric oxide occur in ionized state and their ionization is caused by the ultraviolet radiation. The lowest sub-region of heterosphere is called thermosphere. It is 400 km away from the earth and contains mixture of nitrogen (N2) and oxygen (02) in the proportion of 1:1. Further, in this zone the temperature decreases as the distance from sun increases.  

5.     Exosphere: It is the outer fringe of atmosphere which extends about 20,000 km from the earth. The dominant element in this zone is hydrogen and its temperature ranges from 200 to 10,000°C. The higher temperature is due to solar energy or radiant energy of sun. The lower part of exosphere contains abundance of helium besides hydrogen and therefore, is also called 'Helium zone'.  

Importance of atmosphere 

The role of atmosphere in the maintenance of the biosphere is great and is accomplished as follows:      

1. Atmosphere regulates the temperature of the earth crust. The gases that are presence in atmosphere are able of absorbing large wavelength radiations and is responsible for maintain the temperature in which life activities are possible. For instance, moon has no atmosphere. At equator, the surface temperature  12 Environmental Biology  increases to 101°C in day time but during night, it falls to -lS0°C. No life can survive at these extreme temperatures.  
2.  The pressure and temperature form the precipitation which then regulates the abundance and composition of biotic communities on the earth surface.  
3. The atmosphere protects the earth surface from the ultra-violet rays originated from the sunlight. These rays severely damage the terrestrial life on the earth.   
4. Atmosphere is effective medium for the transfer and dissemination of gaseous wastes. 
5.  Pollutants in the atmosphere are removed by more affective mechanism than operating on land or in water. The entire load of pollutants is brought down with snow, dew or rain which clean the atmosphere.  

  Major zones of atmosphere  

Hydrosphere 

                          More than three-fourth of the earth surface i.e., 71% is covered by hydrosphere. The main component of which is water. Water is one of the most unusual natural compound found on the earth and it is also one of the most important constituent of biosphere. Life began on the earth in the sea. Water is also essential for the maintenance of life and also serves as the medium for several ecosystems. Water occur in three forms viz., solid (ice), liquid (water) and gaseous (vapour) forms. Water may be freshwater or marine and thus, it forms two different types of aquatic environments viz., freshwater environment and marine environment. 

            I. Global distribution of water  Of the total estimated 'water on the earth and its atmosphere, only about 5% is actually or potentially free Environment 13  and is in circulation, remaining 95% of the earth's water is bound in the lithosphere and in the sedimentary rocks. Freshwater amounts to only about 3% of the total supply and three-quarters of it is bound up in the polar ice caps and glaciers. Water is present in three forms in nature: 

i. atmospheric moisture,

 ii. precipitation or rainfall, and

 iii. soil water. 

1. Atmospheric moisture: It occurs in the form of humidity, fog or cloud. Clouds are formed due to the movement of air upward from land surface towards cooler sides of the atmosphere, whereas, fog is caused due to the cooling of air at or near the land surface and is generally continuous from the surface upwards.
2. .Precipitation or rainfall: It is the chief source of the soil moisture. Precipitation affects plants as snow, hail and sleet. Hail cause damage to aerial parts of the plants, whereas, snow mayor may not harm the plants. 
3.  Soil water: It forms the chief source of water for plants and comes on the earth as rain. Some of the rainwater evaporates in the atmosphere before it reaches the ground and thus it depicts the relative humidity, which is invisible vapour of the air. During heavy and long period of age | rainfall, relative humidity may reach upto  100%. 

II. Importance of water to biosphere  Water is an important contituent of the biosphere. Its importance is summarized as follows: 

1. Water is an important, necessary and abundant constituent of the biosphere. The body of an organism is composed of about 70% of water by its weight. Water represents the most extensive medium for animal life.

 2. The habitats of living organisms are aquatic or terrestrial ones is based mainly on the amount of  

14 Environmental Biology water present in the respective environment. On this basis plants are classified into hydrocoles (water loving), mesocoles (neither require excess or less) and xerocoles (dry situation). 

3. Water acts as a solvent for the metabolic activities of living organisms. 

4. Water serves as a vehicle for the transport of material within the bodies of organisms. Water also acts as a regulator of temperature for plants and animals.

 Lithosphere  

The word lithosphere refers to the layers of rocks on the earth's surface both on the continents and oceanic floors.

Lithosphere forms a relatively thin (50-100 km thick) crust which is thicker in the contents than the ocean floor. Below the lithosphere lies the mantle which extends upto a depth of 2,900 km. Manfle like lithosphere can also be divided into (i). outer 100 ~400 km thick, asthenosphere (i.e. inner silicate layer) having materials rich in silica and magnesium and (ii) inner 2,400 to 2,750 km thick mesosphere which is transitional zone of mixed materials and silicates. The central part of the earth, core is about 3,500 km thick. The core consists of metals in liquid state due to high temperature and pressure.  Lithosphere  though literally means a sphere of rocks is also involves the study of land forms (i.e., forms of land surface) and the soil, actual medium for the growth.  

    

Of plants, animals and micro-organisms. We would discuss each of these aspects of lithosphere that is a source of various mineral resources and fuels as coal and oil. The soil cover on the land surface is important for the growth of plants and animals. The surface of land is covered by a variety of land forms viz., mountains, plateaus, valleys and plains. Various land forms are important factor that determine the climate of an area and also pattern of land use.  

Properties of the Lithosphere  
An ecosphere is a planetary closed ecological system. In this global ecosystem, the various forms of energy and matter that constitute a given planet interact on a continual basis.     
These layers are referred to as component spheres with the type andextent of each component sphere varying significantly from one particular ecosphere to another. Component spheres that represent a significant portion of an ecosphere are referred to as a primary component spheres. For  
instance, Earth's ecosphere consists of five primary component spheres
which are  the Geosphere, Hydrosphere, Biosphere, Atmosphere, and Magnetosphere.  

Aside from the fact that we are living on it, the lithosphere is where many of the geologic  

processes that affect us originate. The movement of large pieces of the lithosphereaccount  for the global locations of volcanoes, earthquakes, and mountain ranges, as well  as the shape and location of our modern

continents.  

The lithosphere is made up of rocks from two of the Earth's major layers. It contains all of the outer,thin shell of the planet, called the crust, and the uppermost part of the next-lower layer, the mantle.  

The thickness of the lithosphere varies; it's thickest below the continents and thinnest at the mid ocean ridges, raised areas of the seafloor where new seafloor crust is formed.  

The thing all of the rocks in the lithosphere have in common is the way in which they respond to forces applied to them. At the relatively low temperatures found near the Earth's surface, rocks tend to break under stress. Farther down, as temperature and pressure increase, the more likely it is that  rocks will be able to accommodate stress by changing shape, or deforming, compressing, stretching, and bending, rather than breaking.  

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 Ecosphere  

An ecosphere is a planetary closed ecological system. In this global ecosystem, the various forms of energy and matter that constitute a given planet interact on a continual basis.     
These layers are referred to as component spheres with the type andextent of each component sphere varying significantly from one particular ecosphere to another. Component spheres that represent a significant portion of an ecosphere are referred to as a primary component spheres. For  
instance, Earth's ecosphere consists of five primary component spheres
which are  the Geosphere, Hydrosphere, Biosphere, Atmosphere, and Magnetosphere.