Ecology-ecosystem and its types

The word “Ecology” was coined by a German biologist in 1869 . It is derived from the Greek word, “Oikos” meaning “House”.

Ecology is the branch of science that deals with the study of interactions between living organisms and their physical environment. Both are closely inter-related and they have continuous interaction . So that any change in the environment has an effect on the living organisms and vice-versa.

Any unit of biosystem that includes all the organisms which function together (biotic community) in a given area where they interact with the physical environment is known as ecosystem.


The ecosystem is the functional unit in ecology as it consists of both the biotic community (living organisms) and the abiotic environment. The latter has close interaction essential for maintenance of life processes. The interaction is conducted by energy flow (solar energy) in the system and cycling of materials (natural cycles).

From the biological point of view, the ecosystem has the following constituents:

(i) Inorganic substances (carbon, nitrogen, carbon dioxide, water, etc.) involved in natural cycles.

(ii) Organic compounds (proteins, carbohydrates, humic substances) etc.

(iii) Air, water and substrate environment including the climatic regime and other physical factors.

(iv) Producers, autotrophic (i.e., self-sustaining organisms) green plants that can manufacture food from simple inorganic substances.

(v) Heterotrophic (i.e., that depend on others for nourishment) organisms, mainly bacteria, fungi and
animals which live on other organisms or particulate organic matter.

(vi) Micro-consumers, decomposers, mainly bacteria, fungi which obtain their energy by breaking down dead tissues or by absorbing dissolved organic matter, extracted from plants or other organisms.

Fig. : Grassland and pond ecosystems  

The decomposers release inorganic nutrients that are utilised by producers. They also supply food for macro-consumers or heterotrophic organisms. Bacteria, fungi (and animals) often excrete hormone-like substances that inhibit or stimulate other biotic components of the ecosystem.

Typical profiles of a grassland ecosystem and of a pond ecosystem are shown in Fig.

Land-based Ecosystem

Land (terrestrial) ecosystems depend largely on the climate and soil. Higher plants and animals have evolved on land. For example, seed plants, insects, warm-blooded vertebrates and micro-organisms dominate on land now.

The major terrestrial communities consist of herbaceous plants, shrubs, grass and also woody trees besides numerous insects, arthropods, birds, etc.

Marine Ecosystem

Oceans occupy 70 per cent of earth’s surface, offering habitat to numerous plants (mainly algae), animals like zoo plankton, shrimps, oysters, fishes, reptiles, birds and mammals. They serve as the sink of a large quantity of run- off and wastes from land.

Marine water has a high salt content (about 3.5% by weight) and poor fertility due to lack of nitrates and phosphates as compared to freshwater. Marine life is abundant near the shore and in the continental shelf. The species include commercial fishes, large sea mammals like whales and seals.

Freshwater Ecosystem

Freshwater bodies (ponds, lakes, rivers, springs) are rich in nutrients (nitrates, phosphates) and provide good habitat for phytoplankton, zooplankton, aquatic plants and fishes.

Wetland Ecosystems

Wetlands are transitional lands between terrestrial and eco-systems where water stands at 2.5 to 300 cm during most of the year. They include valuable natural ecosystem harbouring a wide variety of plants, animals, fishes and micro- organisms. They are at present in danger due to increasing urbanization as in the case of eastern part of Kolkata.

Mangroves (Forest between Land and Sea)

Mangroves are important forest communities in tidal zones or equatorial and tropical coasts. For example, the Sunderbans in the Gangetic estuarine delta touching the Bay of Bengal offer important mangroves, habitat of wild animals including Royal Bengal Tiger and of interesting plant species.


  1. What is meant by
    (a) Environment?
    (b) Environmental studies?
  2. What do you mean by ecosystem?
  3. Illustrate land ecosystem and also aquatic ecosystem.
  4. Classify the ecosystems on the basis of their habitats. Give examples.

Read Also

Share on:

Leave a Comment