Unit 2: Natural resources and ecosystem

Part A: Natural Resources

1. Introduction to Natural Resources

Definition: Natural resources are materials or substances such as minerals, forests, water, and fertile land that occur in nature and can be used for economic gain or human survival.

2. Classification of Resources

A. Renewable Resources

Resources that can be replenished or reproduced by physical, chemical, or mechanical processes within a short span of time.

• Examples: Solar energy, wind energy, water, forests, wildlife.
• Characteristics: Usually inexhaustible, but sustainable management is required (e.g., forests can be depleted if cut faster than they grow).

B. Non-Renewable Resources

Resources that occur over a very long geological time. These are finite and cannot be replenished once exhausted.

• Examples: Fossil fuels (coal, petroleum), minerals, nuclear fuels.
• Characteristics: Exhaustible; their rate of consumption exceeds the rate of formation.

3. Specific Resources: Problems and Remedial Measures

A. Forest Resources

Uses: Timber, fuel wood, fodder, production of oxygen (lungs of the earth), habitat for wildlife, regulation of hydrological cycle.

• Associated Problems:
  • Deforestation: Permanent destruction of forests for agriculture or urbanization.
  • Timber Extraction: Illegal logging disturbs ecosystem stability.
  • Mining and Dams: Submergence of forest tracts and displacement of tribal communities.
• Remedial Measures:
  • Afforestation/Reforestation: Planting trees on barren land or replanting in deforested areas.
  • Social Forestry: Involving local communities in forest management (Joint Forest Management).
  • Sustainable Logging: Selective cutting rather than clear-cutting.

B. Water Resources

Uses: Domestic consumption, agriculture (irrigation), industrial use, hydroelectric power.

• Associated Problems:
  • Over-utilization: Excessive pumping of groundwater causing a drop in water tables.
  • Floods and Droughts: Caused by irregular rainfall and deforestation.
  • Conflicts: Disputes over water sharing (e.g., interstate river disputes).
  • Dams: Benefits include electricity and irrigation; problems include displacement of people, siltation, and seismic risks.
• Remedial Measures:
  • Rainwater Harvesting: Collecting run-off water for future use.
  • Watershed Management: Holistic management of land and water resources.
  • Drip Irrigation: Reducing water wastage in agriculture.

C. Land Resources

Concept: Land is a finite resource supporting vegetation, wildlife, and human infrastructure.

• Associated Problems:
  • Land Degradation: Decline in land quality caused by human activities.
  • Soil Erosion: Removal of topsoil by wind or water.
  • Desertification: Transformation of fertile land into desert due to overgrazing or deforestation.
  • Landslides: Downward movement of soil/rock, aggravated by construction in hilly areas.
• Remedial Measures:
  • Terrace Farming: Reduces slope length to prevent erosion.
  • Wind Breaks/Shelter Belts: Planting trees to reduce wind speed.
  • Controlled Grazing: Rotating livestock to prevent overgrazing.

D. Energy Resources

Concept: Energy is required for heat, light, and industrial production.

• Associated Problems:
  • Dependency on Fossil Fuels: High pollution levels and greenhouse gas emissions.
  • Energy Crisis: Gap between demand and supply.
• Remedial Measures:
  • Shift to Alternate Energy: Promoting solar, wind, geothermal, and biomass energy.
  • Energy Efficiency: Using LED lights, energy-efficient appliances (star rated).
  • Bio-fuels: Using ethanol or biogas as alternatives to petrol/diesel.

4. Role of Individual in Conservation of Natural Resources

Conservation refers to the sustainable use and protection of resources for future generations.

• The 3 R’s Principle:
  • Reduce: Minimize consumption (e.g., switch off lights, save water).
  • Reuse: Use items multiple times (e.g., cloth bags instead of plastic, glass jars).
  • Recycle: Process waste materials into new products (e.g., paper, metal, plastic).
• Specific Actions:
  • Use public transport or carpooling.
  • Install rainwater harvesting systems at home.
  • Plant trees and maintain local gardens.
  • Avoid single-use plastics.
  • Spread awareness in the community.

Part B: Ecosystem

1. Concept of Ecosystem

Definition: An ecosystem is a functional unit of nature where living organisms (biotic) interact among themselves and also with the surrounding physical environment (abiotic).

• Term Coined By: A.G. Tansley (1935).

2. Structure of Ecosystem

An ecosystem consists of two main components:

A. Abiotic Components (Non-living)

• Physical factors: Temperature, light, humidity, precipitation, wind.
• Chemical factors: Soil pH, minerals, gases (Oxygen, Nitrogen, CO2).

B. Biotic Components (Living)

1. Producers (Autotrophs): Organisms that synthesize their own food using sunlight (photosynthesis).
   • Examples: Green plants, algae, phytoplankton.
2. Consumers (Heterotrophs): Organisms that depend on others for food.
   • Primary Consumers (Herbivores): Eat producers (e.g., rabbit, cow, grasshopper).
   • Secondary Consumers (Primary Carnivores): Eat herbivores (e.g., frog, cat).
   • Tertiary Consumers (Top Carnivores): Eat other carnivores (e.g., lion, hawk).
3. Decomposers (Saprotrophs): Microorganisms that break down dead organic matter into simple inorganic substances, recycling nutrients back to the soil.
   • Examples: Bacteria, fungi.

3. Functions of Ecosystem

1. Energy Flow: Unidirectional flow of energy from sun to producers to consumers.
2. Nutrient Cycling (Biogeochemical Cycles): Circulation of nutrients (Carbon, Nitrogen, Phosphorus) between biotic and abiotic components.
3. Homeostasis: The ability of an ecosystem to maintain equilibrium/balance.

4. Types of Ecosystems

A. Natural Ecosystems

Operate under natural conditions without major human interference.

• Terrestrial: Forest, Grassland, Desert.
• Aquatic:
  • Freshwater: Lotic (running water like rivers) and Lentic (standing water like ponds).
  • Marine: Oceans, estuaries.

B. Artificial (Man-made) Ecosystems

Maintained and manipulated by humans.

• Examples: Croplands (agriculture), aquariums, botanical gardens, dams.

5. Energy Flow in an Ecosystem

Sunlight is the ultimate source of energy. Energy flow follows the Laws of Thermodynamics.

• 10% Law (Lindeman, 1942): Only about 10% of the energy is transferred from one trophic level to the next. The remaining 90% is lost as heat (respiration/metabolism).

A. Food Chains

A linear sequence of organisms where nutrients and energy are transferred from one organism to another.

1. Grazing Food Chain: Starts with green plants.
   • Example: Grass Grasshopper Frog Snake Hawk.
2. Detritus Food Chain: Starts with dead organic matter.
   • Example: Dead leaves Wood louse Blackbird.

B. Food Webs

A complex network of interconnected food chains.

• Significance: Provides stability to the ecosystem. If one species is removed, the predator has alternative food sources.

6. Ecological Pyramids

A graphical representation of the trophic structure and function of an ecosystem.

A. Pyramid of Number

Represents the number of individuals at each trophic level.

• Upright: Grassland ecosystem (Many grasses fewer herbivores few carnivores).
• Inverted: Parasitic food chain (One tree many birds numerous parasites).

B. Pyramid of Biomass

Represents the total dry weight (mass) of organisms at each level.

• Upright: Terrestrial ecosystems (Forests).
• Inverted: Aquatic ecosystems (Biomass of phytoplankton is less than the zooplankton/fish that eat them, but they reproduce rapidly).

C. Pyramid of Energy

Represents the amount of energy passing through each trophic level over a period.

• Shape: Always Upright.
• Reason: Energy is always lost as heat at each step; it never increases.

7. Ecological Succession

The orderly process of change in the species structure of an ecological community over time.

Types of Succession

1. Primary Succession: Occurs in lifeless areas where no soil exists (e.g., bare rock, cooled lava, sand dunes). It is a slow process (thousands of years).
2. Secondary Succession: Occurs in areas where a community previously existed but was destroyed (e.g., forest fire, flooded land). Faster process as soil is already present.

Stages of Succession

1. Nudation: Formation of a bare area.
2. Invasion: Arrival of reproductive bodies (spores/seeds).
   • Pioneer Species: The first species to colonize (e.g., Lichens on rocks).
3. Competition and Co-action: Struggle for resources among species.
4. Reaction: Modification of the environment by living organisms (e.g., lichens breaking rock into soil).
5. Stabilization (Climax Community): The final, stable stage that is in equilibrium with the environment (e.g., a mature forest).