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Ecosystem

The total living factor (biotic) and total non-living factor (abiotic) of the environment present in a particular area is called an ecosystem.

The total living factor (biotic) and total non-living factor (abiotic) of the environment present in a particular area is called an ecosystem.

A.G. Tansley – The term “ecosystem” first of all coined by A.G. Tansley.

According to Tansley – An ecosystem is a symbol of the structure and function of nature.

As per E.P. Odum – Father of ecosystem ecology. According to E.P. Odum – Ecosystem is the smallest structural and functional unit of nature or environment.

Types of Ecosystems

(1) Natural Ecosystem –

(a)Terrestrial Ecosystem –

e.g., forest, grassland, tree, desert ecosystem

(b)Aquatic ecosystem –Aquatic ecosystem is again of two types:

(i) Lentic ecosystem Stagnant water, lake, pond, swamp.

(ii) Lotic – Running freshwater ecosystem e.g. – river.

(2) Artificial Ecosystem –Man-made e.g., cropland, Gardens, etc.

On the basis of size-types of ecosystems

(i)            Mega ecosystem – Ocean/Sea

(ii)           Macroecosystem – Forest

(iii)          Microecosystem – Pond

(iv)         Nanoecosystem – Drop of water

Component of Ecosystem

1. Abiotic components:

Consists of non-living substances and factors like.

                (i)            Climatic factors i.e. air, water, light, temperature, and precipitation.

                (ii)           Edaphic factors like soil composition.

                (iii)          Topographic factors i.e. mountains, slopes.

2. Biotic components:

They constitute producers or transducers, consumers and decomposers or micro-consumers or saprotrophs.

(I) Biotic components:

Living organisms, i.e., plants, animals, and microorganisms constitute a biotic component of the ecosystem.

1. Producers:

They are green photosynthetic plants that entrap solar energy through chlorophyll to synthesize organic food from inorganic raw materials.

The green plants are thus termed autotrophs as they are capable of synthesizing their own food materials.

They have also termed transducers as they change radiant energy into chemical energy.

Complex organic substances are utilized for building up their bodies and for releasing energy required for various metabolic and physiological activities.

2. Consumers:

They are the animals that are not capable of synthesizing food materials but feed upon other organisms or their parts.

They are thus called heterotrophs.

They are also called phagotrophic as they ingest solid food materials.

The consumers are mainly of two types i.e., herbivores and carnivores.

Herbivores are termed primary consumers as they obtain food directly from plants.

Cattle, deer, goats, rabbits, mice, grasshoppers, etc., are common herbivores in terrestrial ecosystems, and crustaceans, mollusks, and protozoans are common herbivores in aquatic ecosystems.

 Some carnivores (e.g., frogs, cats, jackals, foxes, some fishes, etc.) feed upon herbivores and are thus termed secondary consumers.

Other carnivores feed upon secondary consumers, not eating the herbivores.

They are termed tertiary consumers (e.g., wolf, peacock, etc).

Some carnivores are thus eaten by other larger and stronger carnivores.

However, some larger and stronger carnivores (e.g., tigers and lions) never become prey to any animal and act as predators only. They are called top carnivores.

3. Decomposers:

They are saprophytic micro-organisms (bacteria, actinomycetes, and fungi) deriving their food material from organic matter present in dead remains of plants and animals.

They secrete digestive enzymes which convert complex organic substances into simpler ones.

A part of the digested organic matter is assimilated by the micro-organisms and the rest is broken down into simpler inorganic compounds for recycling.

They bring the about cyclic exchange of materials between the biotic community and the environment. They are thus very essential components of an ecosystem.

They are also called reducers as they are capable of degrading dead organisms.

Some workers differentiated a few other categories of living beings amongst the biotic components of an ecosystem.

They are scavengers, detrivores, and parasites.

Parasites belong to diverse groups, e.g., bacteria, fungi, protozoans, worms, etc.  Every type of living being can be attacked by parasites.

Detrivoresare animals that feed on detritus e.g., termites, earthworms etc. They are helpful in the quick disposal of dead bodies.

Scavengersare animals that feed on dead or injured animals and they clean the earth of organic garbages e.g., carrion, Marabou storks, Crow, and Vultures (Full-time scar vengers)

(II) Abiotic Components:

Non-living factors such as temperature, water, light, etc., constitute abiotic components of the ecosystem.

They are mainly of three types, i.e., climatic, topographic, and edaphic.

Different abiotic factors in an ecosystem are described below.

1. Temperature:

Every organism has a specific range to which it is adapted to live. There are some exceptions like prokaryotes and encysted protozoan which can withstand extremes of temperature.

2. Light: It plays, a crucial role in the ecosystem as it is sunlight which is the direct or indirect source of energy for all types of living organisms. It is the driving force of an ecosystem.

3. Wind:

The wind has a more pronounced effect on plants than on animals.

Wind velocity increases the rate of transpiration.

The wind brings about pollination in most of the gymnosperms and some angiospermswhich is essential for seed formation and hence perpetuation of species.

It brings about the dispersal of fruits and seeds, necessary to avoid overcrowding andcompetition.

Wind affects plant and animal populations by causing soil erosion in dry areas.

4. Humidity:

It refers to water vapor or moisture content of the atmosphere and affects the water loss from the body surface of terrestrial organisms that occurs through evaporation, perspiration, and transpiration.

5.Precipitation:

It occurs in different forms like rainfall, dew, hail, snow, etc. Rainfall is the most significant of these and is the main determinant of the composition of the biotic community.

6.Water:

Availability of water in soil, ponds, rivers, lakes, etc., mainly depends upon rainfall which controls the distribution of animals through its effect on water availability.

7.Topography:

Topography is the surface behavior of the earth like slope, altitude, hills, plains, mountain chains, exposure, etc. These factors affect vegetation and consequently animal life indirectly through their effect on rainfall, light intensity, wind velocity, the water content in the soil, etc. Vegetation on two sides of a hill, one facing the sun and the other away, differs because of the difference in environmental conditions, like humidity, light duration, light intensity, rainfall, etc., as two faces of a hill receive different amounts of solar radiation and wind action. Flora and fauna on the edge of the pond and the middle of a pond and, on or underside of the rock are different for a similar reason.

8.Soil:

The edaphic factors, i.e., the factors relating to the soil such as soil texture (sand, loam, or clay), soil pH (acidic or alkaline), soil water, soil aeration, mineral contents of the soil, etc.,determine the distribution of plants and of animals too, which depends upon vegetation.

Read Also: Pohela Boishakh: Shubho Nabo Barsho!

Manoj Gupta

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