Q.9 What is meant by structure of an ecosystem? Explain the various components of an ecosystem structure. Discuss the functions of an ecosystem also. (AKTU. - 2006-07)
Related Questions -
Q. Give an account of the structure and function of a balanced ecosystem. (AKTU. - 2008-09)
Q. What are the basic components of an ecosystem? Outline the concept of balanced ecosystem. (AKTU. - 2009 - 10)
Q. Enumerate and discuss the various segments of environment in brief.
(AKTU. - 2011 - 12)
Ans. Structure Of Ecosystem: -
All types of natural and engineered ecosystem consist of two major components - one is the living or biotic component and the other is the non-living or abiotic component. Biotic components comprise different species of plants and animals, where as abiotic components include nutrients, water and climatic factors.
Every ecosystem consists of three major classes of organisms which help in maintaining the biologial cycling of materials through it. The three main groups are producers, consumers and decomposer. The first group producers includes plants and some bacteria that are capable of producing their own food either by the process of photosynthesis or by chemical synthesis. The second group - consumers - includes animal that cannot produce their own food and obtain energy from the producers. The third group - decomposers - includes fungi and some bacteria that feed on dead and decaying matter (containing both producers and consumers) and decompose the organic matter (containing both producers and consumers) and decompose the organic matter present in it to inorganic matter, which may again be utilized by the producers. Therefore, ddecomposers aid in recyling the inorganic matter through the biosphere; they are thus, also known as the recylers of biosphere. The biotic and abiotic factors of an ecosystem are shown in figure.
Components of an ecosystem structure: -
Every ecosystem has two major components, viz., abiotic and biotic.
1. Abiotic component: -
It is the non-living component of the ecosystem and includes:
Physical or climatic factors such as soil, temperature, light and water; and Chemical factors constituting the inorganic and organic substances. The inorganic substances include C, H, N, K, P, S, etc., that are involved in mineral (nutrient) cycles and are present in an ecosystem at any given time. The organic substances include carbohydrates, lipids, proteins and humus, and are present in the biomass or in the environment.
2. Biotic component: -
It includes the living components of the ecosystem and is made of many different populations of species which are interdependent upon each other in the ecosystem.
The living component of an ecosystem includes:
(1) Autotrophic component: -
It is the component in which fixation of light energy, use of simple inorganic substances and build up of complex organic substances predominate. The members (organisms) of autotrophic component are producers which are autotrops (self-nourishing organism) such as algae, green plants and photosynthetic bacteria.
(2) Heterotrophic component: -
It is the component in which utilization, rearrangement and decomposition (breakdown) of complex organic substances predominate. The members (organisms) of heterotrophic component are called consumers which are heterotrophs (dependent on others for food) such as animals. They consume the organic matter built up by the producers (or autotrophs). The heterotrophs are further categorized as:
(a) Macroconsumers: -
Macroconsumers are heterotrophs, which in an order as they occur in a food chain are-herbivores, omnivores or carnivores. Herbivores, also known as primary consumers, feed directly on living plants or plant residues, i.e. they have vegetarian diet. Carnivores are secondary or tertiary consumers which feed on consumers, i.e. they have non-vegetarian diet. While omnivores are consumers which feed on producers as well as on primary consumers, i.e. they have vegetarian as well as non-vegetarian diet.
(b) Saprotrophs: -
These are microconsumers, popularly known as decomposers, such as bacteria, fungi, flagellates and actinomycetes. They feed on organic compounds of dead or living protoplasm of plants and animals for their food and energy. They absorb some of the decomposition (or breakdown) products and release inorganic compounds (nutrients ) in the ecosystem, making them available again to producers (autotrophs).
Function of ecosystem: -
The functional aspects of an ecosystem illustrate how an ecosystem works or operate under natural conditions.
The energy flows in non-cyclic manner (undirectional) from sun to the decomposers via producers and macroconsumers (hetrotrophs), whereas the minerals (nutrients) circulate in a cyclic manner. It should be noted here that the cycling of the minerals is accomplished by different biogeochemical (nutrient) cycles superimposed upon the unidirectional energy flow through the biotic component of the ecosystem. Further, the energy not only flows unidirectionally but also lost from the system in many ways and that minerals too similarly show a net loss in many ways.
Balanced Ecosystem: -
An ecosystem is balanced when the biotic (living) and abiotic (non-living) parts of the ecosystem are in equilibrium. This means that the nutrients are able to cycle efficiently, and no community of organisms or natural phenomena is interrupting the flow of energy and nutrients to other parts of the ecosystem.
