MEV 011: Unit 10 - Principle and Concept Of Ecosystem

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 UNIT 10 – PRINCIPLE AND CONCEPT OF ECOSYSTEM

10.1 Introduction

The ecosystem is a fundamental concept in ecology that describes the complex network of interactions between living organisms (biotic components) and their physical environment (abiotic components). These interactions sustain life and enable the circulation of matter and flow of energy. Understanding the principles and functioning of ecosystems helps in environmental conservation, resource management, and sustainability.

10.2 Objectives

After studying this unit, you should be able to:

·         Define and explain the concept of an ecosystem.

·         Describe the structural and functional components of an ecosystem.

·         Understand ecological pyramids, energy flow, and productivity.

·         Explain material cycling and ecological interactions.

·         Understand the concept of ecological modelling.

10.3 Principle and Concept of Ecosystem

An ecosystem is a self-regulating unit composed of biotic (living) and abiotic (non-living) components that interact with each other to maintain ecological balance. The concept was first introduced by Arthur Tansley (1935).

·         Biotic components: Producers (plants), consumers (herbivores, carnivores), decomposers (fungi, bacteria).

·         Abiotic components: Sunlight, temperature, soil, water, air, nutrients.

Principles of Ecosystem:

1.      Interdependence: All organisms are dependent on each other and on their environment.

2.      Flow of Energy: Solar energy is the main source; it flows in one direction – from sun to producers to consumers.

3.      Cycling of Materials: Nutrients like carbon, nitrogen, phosphorus are continuously recycled.

4.      Dynamic Equilibrium: Ecosystems are in a constant state of balance, adjusting to changes.

5.      Self-regulation: Ecosystems tend to resist sudden changes through feedback mechanisms.

10.4 Structure of Ecosystem

The structure includes:

·         Abiotic structure: Sunlight, rainfall, minerals, pH, wind, temperature.

·         Biotic structure:

o    Producers (autotrophs): e.g., green plants, algae.

o    Consumers (heterotrophs):

§  Primary consumers (herbivores),

§  Secondary (carnivores),

§  Tertiary (top predators).

o    Decomposers: Organisms that break down dead matter – e.g., fungi, bacteria.

10.5 Function of Ecosystem

Functions involve:

·         Energy flow through food chains and food webs.

·         Nutrient cycling (biogeochemical cycles).

·         Support for life through provision of food, air, water.

·         Regulation of climate and natural processes.

10.6 Process of Ecosystem Functioning

·         Photosynthesis: Main energy fixation process.

·         Herbivory and predation: Transfer of energy.

·         Decomposition: Recycling of nutrients.

·         Respiration: Energy release for life processes.

All these processes operate in unison to maintain balance and productivity.

10.7 Ecological Pyramids

Ecological pyramids are graphical representations of trophic levels:

·         Pyramid of Number: Shows number of organisms at each level.

·         Pyramid of Biomass: Shows total mass of organisms.

·         Pyramid of Energy: Always upright; shows energy flow.

These pyramids illustrate the decline in energy, biomass, and population as one moves up the food chain.

10.8 Energy Flow

·         Energy enters ecosystems via sunlight.

·         Captured by producers and transferred through consumers.

·         Follows the 10% Law: Only 10% of energy is transferred to the next level; the rest is lost as heat.

·         Food chains and food webs represent these energy transfers.

10.9 Productivity of Ecosystem

Productivity refers to the rate at which energy is produced or biomass is generated:

·         Primary productivity: Energy produced by autotrophs.

o    Gross Primary Productivity (GPP)

o    Net Primary Productivity (NPP = GPP - plant respiration)

·         Secondary productivity: Energy used for biomass in consumers.

Different ecosystems have varying productivity levels:

·         Highest: Tropical rainforests, wetlands.

·         Lowest: Deserts, open oceans.

10.10 Material Cycling

Ecosystems cycle essential elements through biogeochemical cycles:

·         Carbon Cycle

·         Nitrogen Cycle

·         Phosphorus Cycle

·         Water Cycle

These cycles maintain the availability of essential nutrients and support sustainability of ecosystems.

10.11 Ecological Interactions

Species interact in various ways:

·         Predation: One organism kills and eats another.

·         Parasitism: One benefits, other is harmed.

·         Mutualism: Both benefit (e.g., bees and flowers).

·         Commensalism: One benefits, other is unaffected.

·         Competition: Both are harmed; competing for resources.

These interactions regulate population size and biodiversity.

10.12 Ecological Modelling

Ecological models are mathematical or computer-based representations of ecosystems. They help:

·         Predict changes due to environmental impacts.

·         Simulate energy flow, population growth, climate effects.

·         Support management and conservation strategies.

Models are based on real-time data and assumptions and are useful in research and policy-making.

10.13 Let Us Sum Up

·         Ecosystems are structured units where biotic and abiotic components interact.

·         Energy flows in a one-way direction, while matter cycles.

·         Ecological pyramids and productivity help assess ecosystem health.

·         Interactions among organisms regulate populations and biodiversity.

·         Ecological modelling is a powerful tool to understand and predict ecosystem behavior.

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