Concept of Ecosystem

Ecosystem: A self-regulating, self-sustaining functional unit of nature comprising all living organisms (biotic components) interacting with each other and with their non-living surroundings (abiotic components) within a defined area, involving continuous exchange of matter and energy.

• The term "ecosystem" was coined by A.G. Tansley in 1935. Ecosystems vary enormously in size – from a small pond or crop field to an entire biosphere

The structure of an ecosystem is described in terms of the composition and organisation of its components.

Biotic vs Abiotic Components

Biotic Components: Roles

1. Productivity – rate of biomass/energy generation by producers (gross vs net primary productivity).
2. Decomposition – breakdown of complex organic matter into simpler inorganic substances by decomposers.
3. Energy Flow – unidirectional transfer of energy from producers through successive trophic levels.
4. Nutrient Cycling – circulation of essential elements (carbon, nitrogen, phosphorus) between biotic and abiotic components.

• An ecosystem (a term coined by A.G. Tansley in 1935) is a self-sustaining unit where living (biotic) and non-living (abiotic) components continuously interact and exchange energy.
• It is structurally composed of abiotic factors (physical/chemical elements like sunlight, water, and soil) and biotic factors (all living organisms).
• The living organisms are divided by their roles into producers (synthesise food), consumers (feed on others), and decomposers (recycle nutrients from dead matter).
• Ecosystems are classified by their origin into natural (forests, oceans) or artificial/man-made (crop fields, aquariums) and by habitat into terrestrial or aquatic.
• Every ecosystem operates through four core functions: productivity (biomass generation), decomposition, a unidirectional energy flow, and continuous nutrient cycling.