COMPONENTS OF ECOSYSTEM
Ecosystem consists of two components:
-
Biotic component
-
Abiotic component (environment, soil etc.)
BIOTIC COMPONENTS:
Different biotic components are connected, through food chain or other relation. That is why it is said that all the living organisms comes under biotic components. Food available for biotic components can be
synthesized, from inorganic raw material by the autotrophs only.
Biotic components are of three types which are essential for ecosystem
Producers:
All the autotrophs of ecosystem are called as producers. The green plants are the main producers. Green plants absorb solar energy and convert it into chemical energy. It means energy enters into the ecosystem through the producers. The solar energy is the only ultimate source of energy in ecosystem. This energy is available to the remaining living organisms through the medium of food.
Consumers:
Those organisms which consume food (eat food) prepared by producers are called consumers. The consumers depend on producers for food, directly or indirectly. The consumers get their food by eating other organisms or their products. All the animals are consumers. They are known as heterotrophs. Consumers can be further divided into three groups: herbivores, carnivores and omnivores.
(i) Herbivores:
Some animals eat only plants (or their products). Those animals which eat only plants are called herbivores. The herbivores may eat grasses, leaves, grains, fruits or the bark of trees. Some of the examples of herbivores are: Cow, Buffalo, Goat, Sheep, Horse, Deer, Camel, Ass, Ox, Elephant, Monkey, Squirrel, Rabbit and Hippopotamus. Since herbivores obtain their food directly from plants (or producers), therefore, herbivores (like Cattle, Deer, Goat, etc.) are Primary Consumers.
(ii) Carnivores:
Some animals eat only other animals. They do not eat plant food at all. Those animals which eat only other animals as food are called carnivores. Some of the examples of the carnivores are: Lion, Tiger, Frog, Vulture, Kingfisher, Lizard, Wolf, Snake and Hawk. The carnivores are usually of two types (a) small carnivores and (b) large carnivores. The small carnivores which feed on herbivores (primary consumers) are called secondary consumers. For example, a grasshopper, rat, seed eating birds and frog, etc., are Secondary Consumers. The large carnivores (or top carnivores) which feed upon the small carnivores (secondary consumers) are called tertiary consumers. For example, lion, tiger, birds of prey (such as hawk) and humans (man) are some of the Tertiary Consumers.
(iii) Omnivores:
Some animals eat both, plants as well as other animals. Those animals which eat both, plants and animals are called omnivores. Some of the examples of omnivores are: Man (Human Beings), Dog, Crow, Sparrow, Bear, Mynah and Ant.
Decomposers or Microconsumers:
Those living organisms which decompose the dead bodies of producers and consumers and release mineral substances again into the soil which are present in the dead bodies. So that decomposers help in mineral cycle. Only because of this land is the main source of minerals. The main decomposers in ecosystem are - bacteria and fungi which decompose continuously dead animals and dead plants.
Importance of Decomposers:
The decomposers help in decomposing the dead bodies of plants and animals, and hence act as cleansing agents of environment. Thus, it is only due to the presence of decomposers that the various nutrient elements which were initially taken by plants from the soil, air and water are returned to the soil, air and water, after the death of plants and animals. In the absence of decomposers, the soil, air and water would not be replenished by elements from the bodies of dead organisms. Thus, the decomposers help in recycling the materials in the ecosystem so that the process of life may go on and on like an unending chain.
Scavengers :
Vulture never kills any animal so that vulture is a scavenger, not adecomposer. The process of decomposition takes place outside the body of bacteria. Thebreakdown of the food materials takes place in the body of vulture and minerals are releasedinto the soil in the form faecal materials. They are also called as reducers because theydecomposes and remove the dead bodies of the organism.
Abiotic (non-living) component:
These include the non-living physico-chemical factors of the environment. These components not only affect the distribution and structure of organisms but also their behaviour and inter relationships. Abiotic factors include:
(a) Inorganic substances:
Inorganic substances, e.g., carbon, nitrogen, oxygen, calcium, phosphorus etc. and their compounds (water, carbon dioxide, etc.) constitute the main abiotic components. These occur either in the form of compounds dissolved in water, in the soil or in free state in air.
(b) Organic compounds:
These include carbohydrates, proteins, lipids, nucleic acids etc. These are present in living organisms and dead organic matter. The dead organic matter is broken down by the action of decomposers (e.g., bacteria, fungi) into inorganic substances for their recycling.
(c) Climatic factors:
These include light, temperature, humidity, wind, rainfall, water etc. and also edaphic factors (e.g., soil, topography, minerals, pH etc.).
Structure of an Ecosystem :
The characteristic structure of an ecosystem is obtained by the systematic physical organisation of the abiotic and biotic components of that particular ecosystem.
The two main structural features of any ecosystem are its 'species composition' and 'stratification'.
An ecosystem can be represented by depicting the producers - consumers relationship in the given ecosystem.
This is also called the 'Trophic structure' of an ecosystem, wherein each animal population forms the various trophic levels.
The producers (green plants) always form the first trophic level. Herbivores, which feed on producers, are at the second trophic level followed by secondary consumers, tertiary consumers and so on.
Trophic structure of an ecosystem can be described in terms of its total amount of nutrients or the amount of living material.
The amount of nutrients in the soil at any given time is referred as 'standing state' whereas the amount of living material is referred as 'standing crop'.
(d) Functions of an Ecosystem:
The main functions of an ecosystem are :
Energy flow :
-
From sun to producers
-
Producers to consumers
-
Consumers to decomposers
Energy flow in an ecosystem is a key function of an ecosystem. It determines the following two laws of Thermodynamics:
(A) First law :
It states, that energy can neither be created nor destroyed, but can be transferred from one form to other.
(B) Second law :
It states, that every energy change involves the degradation or dissipation of energy, from concentrated to the dispersed form due to metabolic functions, so that only a small part of energy is stored in the biomass.
Productivity:
Ecosystem helps to maintain the productivity, of the system. The rate of organic matter or biomass production is called as productivity. The study of biomass production in the ecosystem is called as production ecology.
Nutrient cycles:
All living organisms get matter from the biosphere component i.e. lithosphere, hydrosphere and atmosphere. Essential elements or inorganic substances are provided by earth and are required by organisms for their body building and metabolism, they are known as biogeochemical or biogenetic nutrients.
Development and stabilization:
This function is necessary for the development and giving stability to various life forms, by undergoing certain modifications.
Mineral cycling (Biogeochemical cycles) :
The chemical elements composing the abiotic components are circulated in an ecosystem starting from nutrient pool (soil) to producers, producers to consumers, consumers to decomposers and then back to the nutrient pool.
BIOME
Various ecosystems combine together in a larger region to constitute a biome.
The total annual rainfall, temperature range, nature of soil, barriers, latitude and altitude determine the nature and extent of a biome. Basically a biome is the largest terrestrial community. Tundra, northern coniferous forests (taiga), deciduous forests, tropical rain forests, mediterranean scrub forests (chapparal), tropical savanah, grass land and deserts are the principal biomes of the world.
BIOSPHERE
A zone having land, water and air where life exists is referred to as biosphere.
or
The life supporting zone of earth, where atmosphere, lithosphere and hydrosphere meet, interact and make life possible is known as biosphere.
The term biosphere was proposed by Eduard Suess(1875).
Biosphere extends to about 22.5 km in thickness from ocean bottom to mountain tops. However all parts of the biosphere are not equally inhabited. Maximum density of organisms is found in tropical rain forests and coral reefs.
The biosphere is the largest biological system. It consists of number of small functional units called ecosystems.A biosphere includes all living organisms and all life supporting regions of the earth. It includes not only terrestrial but the water regions as well. It comprises three regions namely, hydrosphere, lithosphere and atmosphere.
HYDROSPHERE
The region of water on the surface of earth is called hydrosphere. Most of the water found in oceans.
It includes all water components of the earth e.g., oceans, lakes and rivers etc.
LITHOSPHERE
The solid outer portion of the earth, containing soil and rocks is called lithosphere.
It forms the crust of earth. The biosphere is supported by lithosphere.
It comprises solid (terrestrial) parts of the earth e.g., landmasses and rocky materials.
ATMOSPHERE
The part of the earth where air is present is called atmosphere. It envelops the hydrosphere and lithosphere regions of the biosphere. A large number of living organisms are found in the atmosphere. They interact with each other and maintain an equilibrium. It is referred to as ecological balance.
Our planet, the earth comprising hydrosphere, lithosphere and atmosphere constitute a giant ecosystem, the biosphere. In this reference ours is a unique planet.
BIOLOGICAL SYSTEM
The biosphere is called a biological system because just like any other system, a biosphere has different components which receive certain inputs, undergo interaction and give some output. There is a constant interaction between living and non-living components resulting in the transfer of food and energy, which makes it a dynamic but stable system.
Biosphere is considered to be the largest biological system because it is made up of all the non-living and living components on the earth where each component performs a certain function.
