Ecology & Ecosystems
The fundamentals of ecology — the levels of biological organisation, the abiotic and biotic components of an ecosystem, and its types and functions.
Key Takeaways
- An ecosystem is a community of living organisms interacting with their non-living environment.
- Ecosystem components are abiotic (physical) and biotic (producers, consumers, decomposers).
- The term 'ecosystem' was coined by A. G. Tansley (1935); 'ecology' by Ernst Haeckel.
Core concept
Ecology is the study of the interactions between organisms and their environment. Its basic functional unit is the ecosystem — a community of interacting living organisms (the biotic component) together with their non-living surroundings (the abiotic component), functioning as a unit.
Static foundation — levels of organisation
Life is organised in a hierarchy: organism → population → community → ecosystem → biome → biosphere. The biosphere is the sum of all ecosystems — the global zone of life.
Components of an Ecosystem
| Component | Includes | Role |
|---|---|---|
| Abiotic | Sunlight, temperature, water, soil, air, nutrients | The physical and chemical setting |
| Producers (autotrophs) | Green plants, algae, some bacteria | Fix solar energy by photosynthesis — the base of the food chain |
| Consumers (heterotrophs) | Herbivores, carnivores, omnivores | Obtain energy by feeding on others |
| Decomposers (detritivores) | Bacteria, fungi | Break down dead matter and recycle nutrients |
Key Ecology Terms
Tap to reveal.
Functions of an ecosystem
An ecosystem performs four key functions: energy flow (one-way, from the Sun through trophic levels), nutrient cycling (biogeochemical cycles), productivity (fixing energy into biomass), and ecological succession (the gradual, orderly change of a community over time toward a stable 'climax').
Relevance & current linkage
Concepts like ecosystem services (provisioning, regulating, cultural, supporting) frame debates on valuing nature, and underpin ideas such as payment for ecosystem services and natural capital accounting. (Add a current ecosystem-restoration initiative if relevant.)
Prelims trap zones
- Producers = autotrophs; decomposers ≠ producers (decomposers are heterotrophs that recycle nutrients).
- NPP (not GPP) is the energy available to the next trophic level.
- An ecotone is the boundary/transition zone, not a type of ecosystem.
Knowledge Check
2 questions · check your understanding
1. Which of these is a biotic component of an ecosystem?
2. The transition zone between two ecosystems is called a(n):
Prelims Pointers
- Levels of organisation: organism → population → community → ecosystem → biome → biosphere.
- Producers (autotrophs) make their own food; consumers (heterotrophs) depend on others; decomposers break down dead matter.
- Ecosystems are terrestrial (forest, grassland, desert) or aquatic (freshwater, marine).
- Gross Primary Productivity (GPP) minus respiration equals Net Primary Productivity (NPP).
Mains Angle
- 'An ecosystem is a self-regulating and self-sustaining unit.' Discuss.
- Explain the structure and function of an ecosystem.
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