Seven Major Ecological Levels of Organisation

The following points highlight the seven major ecological levels of organisations. The ecological levels are: Organisms, Population, Biological Community, Ecosystem, Landscape, Biome, Biosphere.

1. Organisms

They serve as the fundamental analytical building block for ecology. Each tier of the biological food chain contains units that are specialised for their respective roles. Form, physiology, behaviour, distribution, and adaptations to environmental variables are investigated at this level. Similar creatures can successfully breed with one another, resulting in new species.

All life activities are carried out by the organism itself. However, the various components of an organism cannot function separately. When an organism fits in perfectly, it has adapted to its surroundings. Birth, hatching, growth, maturity, senescence, ageing, and death are all discrete stages in its finite lifespan. Among the many ways in which creatures interact with one another are competition, mutualism, and predation.

2. Population

Populations in ecology are defined as groups of individuals of the same species that share a specific geographic location and interact with one another as a single biotic community.

For example, all individuals of the common grass, Cynodon, in a given area constitute its population. Similarly, the individuals of elephants or tigers in an area constitute their population.

There has been a lot of research on how different populations affect one another. Predator-prey or parasite-host relationships are two examples of these types of interactions. There are numerous types of interactions, including: competition, mutualism, commensalism, parasitism, and predation.

Seven Major Ecological Levels of Organisation

Figure 1: Seven Major Ecological Levels of Organisation

3. Biological Community

Interdependence and interactions among populations of different species in a habitat lead to the organisation of the biotic community. This is the collection of organisms in a certain area, including the flora, fauna, microbes, and fungus that all coexist and influence one another.

There is a higher level of ecological organisation represented by biotic communities, which are distinct from populations. Animals, plants, and decomposers are the three main categories of biotic communities (i.e., bacteria and fungi). Each biotic community is unique in the make-up of its individual species and the way those species interact with one another.

4. Ecosystem

Ecosystems are areas of nature where living things interact with one another and their surrounding environment. A biotic community that is connected with its physical surroundings through the exchange of energy and nutrient recycling makes up an ecosystem. Sir Arthur Tansley first used the term ecosystem in 1935.

The Interaction of organisms with atmosphere

Figure 2: The interaction of organisms with atmosphere

Ecosystems can be recognised as self- regulating and self-sustaining units of landscape, e.g., a pond or a forest. An ecosystem has two basic components:

(i) Abiotic (non-living), and

(ii) Biotic (living organisms).

Abiotic components comprise inorganic materials, such as carbon, nitrogen, oxygen, CO2, water etc., while biotic components include producers, consumers and decomposers.

5. Landscape

A landscape is a unit of land with a natural boundary having a mosaic of patches, which generally represent different ecosystems.

6. Biome

This is a large regional unit characterised by a major vegetation type and associated fauna found in a specific climate zone. The biome includes all associated developing and modified communities occurring within the same climatic region, e.g., forest biomes, grassland and savanna biomes, desert biome, etc. On a global scale, all the earth’s terrestrial biomes and aquatic systems constitute the biosphere.

7. Biosphere

The entire inhabited part of the earth and its atmosphere including the living components is called the biosphere. The global environment consists of three main sub-divisions: (i) The hydrosphere which includes all the water components, (ii) The lithosphere comprises the solid components of the earth’s crust, and (iii) The atmosphere formed of the gaseous envelope of the earth. The biosphere consists of the lower atmosphere, the land and the oceans, rivers and lakes, where living beings are found.