ECOSYSTEM – STRUCTURE & FUNCTION
An ecosystem is a functional unit of nature, where living organisms interact each other and with the physical environment.
Types of ecosystems
- Terrestrial ecosystem: Forest, grassland, desert etc.
- Aquatic ecosystem: Pond, lake, wetland, river & estuary.
- Man-made ecosystem: Crop fields and aquarium.
Entire biosphere is regarded as global ecosystem.
In an ecosystem, biotic and abiotic components interact and function as a unit.
Vertical distribution of different species occupying different levels is called stratification. E.g. in a forest, trees occupy top strata (layer), shrubs the second and herbs & grasses the bottom layers.
Pond (Aquatic ecosystem)
A pond is a shallow, simple, self-sustainable water body that exhibits all basic components of an ecosystem.
- Abiotic components: Water and soil deposit.
- Climatic conditions: Solar input, cycle of temperature, day-length etc.
- Autotrophic components: Phytoplankton, some algae and the floating, submerged and marginal plants.
- Consumers (heterotrophs): Zooplankton, free swimming and bottom dwelling forms.
- Decomposers: Fungi, bacteria and flagellates.
Pond performs all the functions of an ecosystem. E.g.
- Autotrophs convert inorganic into organic material using solar radiant energy.
- Heterotrophs consume the autotrophs.
- Decomposition and mineralization of the dead matter to release them back for reuse by the autotrophs.
4 basic components of functioning of an ecosystem
- Productivity
- Decomposition
- Energy flow
- Nutrient cycling