What is an Ecosystem?
An ecosystem is a dynamic complex of living organisms (plants, animals, and microbes) interacting with one another and with their non-living environment (air, water, and mineral soil) as a system. Ecosystems can vary greatly in size and type, from small ponds to large forests or oceans. The biosphere is a global ecosystem encompassing all local ecosystems on Earth.
Examples of ecosystems include:
- Terrestrial Ecosystems: Forests, grasslands, deserts
- Aquatic Ecosystems: Ponds, lakes, wetlands, rivers, estuaries
- Man-made Ecosystems: Crop fields, aquariums
Types of Ecosystems
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Terrestrial Ecosystems
Includes forests, grasslands, and deserts. Characterized by the dominant vegetation and the climate of the region. -
Aquatic Ecosystems
Includes freshwater systems like ponds and lakes, and marine systems like oceans and estuaries. Focuses on the water environment and its biota.
Ecosystem Inputs
Ecosystem inputs refer to the productivity within an ecosystem. This includes the primary production by plants (photosynthesis) and secondary production by herbivores and predators. Inputs provide the energy and nutrients required for the system’s functioning.
Energy Transfer in Ecosystems
Energy transfer in ecosystems is described by the food chain and food web. The food chain illustrates a linear sequence of energy transfer from producers to consumers. The food web shows the complex network of interconnected food chains. Nutrient cycling is the movement of nutrients through the biotic and abiotic components of the ecosystem.
Ecosystem Outputs
Ecosystem outputs include the degradation of organic matter and energy loss through respiration, heat, and other processes. These outputs contribute to the cycling of nutrients and energy flow within the ecosystem, affecting its overall health and sustainability.
Relationships in Ecosystems
Relationships within ecosystems are characterized by various cycles and interactions, including nutrient cycles (carbon, nitrogen, phosphorus), energy flows (food chains and webs), and ecological interactions (predation, competition, symbiosis). Understanding these relationships helps in appreciating the complexity and interdependence of ecosystem components.
Components of Ecosystems
The interaction of biotic and abiotic components results in a physical structure characteristic of each ecosystem. Key aspects include productivity, decomposition, energy flow, and nutrient cycling.
Key Functions of Ecosystems
To understand ecosystem functions, consider these aspects:
- Productivity: The rate at which energy is converted by autotrophs into organic substances.
- Decomposition: The breakdown of organic matter into simpler substances, recycling nutrients back into the ecosystem.
- Energy Flow: The unidirectional movement of energy through different trophic levels.
- Nutrient Cycling: The recycling of nutrients through the biotic and abiotic components of the ecosystem.
Aquatic Ecosystem Example
A pond is a simple, self-sustainable aquatic ecosystem that exhibits all the basic components of an ecosystem, including abiotic factors, autotrophs, consumers, and decomposers.
Details of a Pond Ecosystem
The pond ecosystem includes:
- Abiotic Components: Water, dissolved substances, and soil.
- Autotrophic Components: Phytoplankton, algae, and aquatic plants.
- Consumers: Zooplankton, free-swimming organisms, and bottom dwellers.
- Decomposers: Fungi, bacteria, and flagellates.
These components work together to perform essential functions such as energy conversion, consumption, and nutrient recycling.
Ecosystem Structure and Function
Explore the components and interactions within an ecosystem, focusing on productivity, decomposition, energy flow, and nutrient cycling.
Ecosystem Components
| Aspect | Description |
|---|---|
| Productivity | The rate at which energy is converted by photosynthetic and chemosynthetic autotrophs to organic substances. |
| Decomposition | The process by which organic substances are broken down into simpler organic or inorganic matter. |
| Energy Flow | The transfer of energy from one organism to another through various trophic levels in an ecosystem. |
| Nutrient Cycling | The circulation of nutrients through the ecosystem, involving processes like decomposition and assimilation. |
Aquatic Ecosystem Example: Pond
| Component | Description |
|---|---|
| Abiotic Factors | Water, dissolved substances, soil deposits, solar input, temperature, day-length, and other climatic conditions. |
| Autotrophs | Phytoplankton, algae, floating, submerged, and marginal plants. |
| Consumers | Zooplankton, free-swimming and bottom-dwelling organisms. |
| Decomposers | Fungi, bacteria, and flagellates, mainly in the pond's bottom. |
Productivity in Ecosystems
A constant input of solar energy is crucial for ecosystem function and sustainability. Primary production is the amount of biomass produced by plants during photosynthesis, measured in weight or energy units.
Primary and Secondary Productivity
Primary productivity is the rate of biomass production by plants through photosynthesis, measured as:
- Gross Primary Productivity (GPP): Total organic matter produced.
- Net Primary Productivity (NPP): GPP minus respiration losses (GPP - R = NPP).
Secondary productivity is the rate of new organic matter formation by consumers.
Factors Influencing Productivity
Primary productivity varies based on:
- Plant species
- Environmental factors
- Availability of nutrients
- Photosynthetic capacity
Annual net primary productivity of the biosphere is approximately 170 billion tons (dry weight). Oceans, despite covering 70% of the surface, contribute only 55 billion tons of this productivity.
Discuss with your teacher why ocean productivity is lower.
Introduction to Decomposition
Decomposition involves the breakdown of complex organic matter into inorganic substances like carbon dioxide, water, and nutrients. This process is crucial for recycling nutrients in ecosystems.
Steps in Decomposition
- Fragmentation: Detritivores like earthworms break down detritus into smaller particles.
- Leaching: Water-soluble inorganic nutrients move down into the soil and precipitate as unavailable salts.
- Catabolism: Bacterial and fungal enzymes degrade detritus into simpler inorganic substances.
- Humification: Accumulation of humus, a dark-colored, resistant substance that serves as a nutrient reservoir.
- Mineralisation: Degradation of humus by microbes, releasing inorganic nutrients back into the soil.
Factors Affecting Decomposition
The rate of decomposition is influenced by:
- Chemical Composition: Detritus rich in lignin and chitin decomposes slower compared to nitrogen-rich and water-soluble substances.
- Climatic Factors: Warm and moist conditions accelerate decomposition, while low temperatures and anaerobic conditions inhibit it.
Decomposition is largely an oxygen-requiring process, with temperature and soil moisture being crucial factors.
Revision
Let's Revise Decomposition in Step by Step Manner.
Decomposition
Decomposers break down complex organic matter into inorganic substances like carbon dioxide, water, and nutrients in a process called decomposition.
Decomposition Rate
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Chemical Composition
Decomposition rate is slower if detritus is rich in lignin and chitin, quicker if detritus is rich in nitrogen and water-soluble substances like sugars.
-
Climatic Factors
Temperature and soil moisture regulate decomposition through their effects on the activities of soil microbes.
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