Unit - I Ecosystem (ES)

An ecosystem is a community of living organisms (plants, animals, microorganisms) interacting with the non-living environment (air, water, soil, sunlight) in a particular area.

Example

  • Forest ecosystem: Trees, animals, insects, soil, water, air

  • Pond ecosystem: Fish, algae, insects, water, sunlight

2. Structure and Components of Ecosystem

Structure of Ecosystem

The ecosystem is made up of two main components:

(A) Biotic Components (Living)

  1. Producers

    • Green plants that make food using sunlight

    • Example: Grass, trees, algae

  2. Consumers

    • Animals that depend on plants or other animals for food

    • Types:

      • Primary consumers: Deer, cow

      • Secondary consumers: Lion, tiger

      • Tertiary consumers: Top predators

  3. Decomposers

    • Break down dead plants and animals into nutrients

    • Example: Bacteria, fungi

(B) Abiotic Components (Non-Living)

  • Air, water, soil

  • Sunlight

  • Temperature

  • Minerals

Simple Example

In a garden ecosystem:

  • Plants → Producers

  • Insects → Consumers

  • Earthworms → Decomposers

3. Types of Ecosystem

(A) Natural Ecosystem

  1. Terrestrial ecosystem (Land)

    • Forest, grassland, desert

  2. Aquatic ecosystem (Water)

    • Pond, river, lake, ocean

(B) Artificial Ecosystem

  • Created by humans

  • Example: Crop field, aquarium, garden

4. Changes in Ecosystem

Natural Changes

  • Floods

  • Earthquakes

  • Volcanic eruptions

  • Climate change

Man-Made Changes

  • Deforestation

  • Industrial pollution

  • Urbanization

  • Overuse of resources

Example

Cutting forests reduces wildlife and affects rainfall.

5. Natural Cycles (Biogeochemical Cycles)

5.1 Carbon Cycle

Definition

The carbon cycle shows how carbon moves between atmosphere, plants, animals, and soil.

Process

  • Plants absorb CO₂ during photosynthesis

  • Animals eat plants

  • Carbon returns to air through respiration and burning fuels

Example

Burning petrol releases carbon dioxide into the air.

5.2 Nitrogen Cycle

Definition

The nitrogen cycle explains how nitrogen moves from air to soil, plants, animals, and back to air.

Steps

  1. Nitrogen fixation (by bacteria)

  2. Nitrification

  3. Assimilation by plants

  4. Decomposition

  5. Denitrification

Example

Nitrogen helps plants grow faster.

5.3 Sulphur Cycle

Definition

Movement of sulphur through air, soil, water, and living organisms.

Sources

  • Volcanic eruptions

  • Burning fossil fuels

Example

Sulphur is needed for making proteins.

5.4 Phosphorus Cycle

Definition

Movement of phosphorus through rocks, soil, water, and organisms.

Special Feature

  • No atmospheric phase

Example

Phosphorus helps in bone and teeth formation.

6. Ecosystem Conservation

Definition

Ecosystem conservation means protecting natural ecosystems from damage and overuse.

Methods

  • Afforestation

  • Wildlife protection

  • Pollution control

  • Sustainable use of resources

Example

Creating national parks to protect animals.

7. Carrying Capacity of Earth

Definition

The carrying capacity is the maximum population that Earth can support without harming natural resources.

Example

Overpopulation leads to shortage of water, food, and energy.

8. Biomes in India

Definition

A biome is a large area with similar climate, plants, and animals.

Major Biomes in India

  • Tropical rainforest

  • Desert (Thar Desert)

  • Grassland

  • Mountain (Himalayas)

  • Coastal regions

9. Ecologically Sensitive Areas (ESA)

Definition

ESA are areas that are fragile and need special protection due to rich biodiversity.

Examples in India

  • Western Ghats

  • Himalayas

  • Coastal areas

Importance

  • Prevents environmental damage

  • Protects rare species

10. Biodiversity

Definition

Biodiversity means the variety of plants, animals, and microorganisms in a region.

Types

  1. Genetic diversity

  2. Species diversity

  3. Ecosystem diversity

Need and Importance

  • Maintains ecological balance

  • Provides food and medicine

  • Supports agriculture and economy

11. IUCN Red List

Definition

The IUCN Red List is a record of endangered and threatened species across the world.

Categories

  • Least Concern

  • Vulnerable

  • Endangered

  • Critically Endangered

  • Extinct

Example

  • Tiger → Endangered

  • Dodo → Extinct

12. Ecological Footprint

Definition

The ecological footprint measures how much natural resources a person or country uses.

Example

High electricity use increases ecological footprint.

13. Virtual Water

Definition

Virtual water is the hidden water used to produce products.

Example

  • 1 kg rice needs about 2500 liters of water

  • 1 cotton shirt uses thousands of liters of water

14. Global Ecological Overshoot

Definition

Global ecological overshoot occurs when humans use more resources than Earth can regenerate in a year.

Example

Using forests faster than they grow back.

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