Ecology Notes with PDF

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I. Core Ecological Concepts

A. Fundamental Definitions & Terminology

• Ecosystem: A community of living organisms interacting with their non-living environment.
  • Coined by A.G. Tansley.
• Biosphere: The largest ecosystem on Earth; the global sum of all ecosystems.
• Ecotone: A transitional zone where two distinct communities or ecosystems meet.
• Ecological Niche: Concept first enunciated by Joseph Grinnell in 1917.
• Deep Ecology: A term first used by Norwegian philosopher Arne Naess in 1972.
• Levels of Biological Organization (Simple to Complex):
  • Organism → Population → Community → Ecosystem → Landscape/Biome → Biosphere.
• Bionomics: A term synonymous with ecology.

B. Types of Ecosystems

1. Based on Origin:
   • Natural Ecosystems: Terrestrial (forests, grasslands) and aquatic (lakes, rivers, oceans).
   • Artificial Ecosystems: Human-made and controlled (e.g., rice fields, farms, orchards).
2. Based on Water Flow (Aquatic):
   • Lentic Ecosystems: Still or slow-moving water (e.g., ponds, lakes, swamps).
   • Lotic Ecosystems: Fast-moving water (e.g., rivers, waterfalls).

C. Ecosystem Components

• Producers (Autotrophs): Organisms that produce their own food (e.g., plants, phytoplankton in oceans).
• Consumers (Heterotrophs): Organisms that consume other organisms for energy.
• Decomposers: Nature’s recyclers (primarily bacteria and fungi) that break down dead organic matter.

II. Energy Flow & Nutrient Cycling

A. Food Chains and Webs

• Food Chain: A linear sequence representing the transfer of energy and nutrients (e.g., Grass → Goat → Human).
• Food Web: A complex network of interconnected food chains, showing the number of organisms eaten.
• Trophic Levels: Producer → Herbivore/Primary Consumer → Carnivore/Secondary Consumer.
• Energy Flow: Energy flows in a unidirectional manner from the sun to producers and then to consumers.

B. Energy Transfer Efficiency

• The 10 Percent Law: Only about 10% of the energy is transferred from one trophic level to the next; the rest is lost as heat, respiration, etc.
• Consequence: The amount of usable energy decreases at each successive level.
• Pyramid of Energy: Is always upright because energy always decreases.
• Pyramid of Biomass:
  • Upright: In terrestrial ecosystems (e.g., grasslands, forests).
  • Inverted: In aquatic ecosystems (e.g., ponds, where phytoplankton biomass is small).

C. Biogeochemical Cycles

• Definition: The cycling of elements (e.g., carbon, nitrogen, phosphorus) between living and non-living components.
• The Phosphorus Cycle:
  • Main Reservoir: Rocks and minerals.
  • Release Mechanism: Weathering of rocks.
• Marine Nutrient Cycling:
  • Marine Upwelling Zones: Areas where deep, cold, nutrient-rich water rises to the surface, supporting high productivity (phytoplankton growth) and rich fisheries.

III. Ecosystem Dynamics & Change

A. Ecological Succession

• Definition: The process by which the structure of a biological community changes over time.
• Sere: The entire sequence of communities in succession.
• Phases of Succession:
  1. Nudation (bare area formation)
  2. Migration (arrival of propagules)
  3. Ecesis (establishment of pioneers)
  4. Reaction (environment modification)
  5. Stabilization (climax community reached).
• Grassland Stability: Trees often don’t replace grasses due to limiting factors like water scarcity and fire.

B. Ecosystem Productivity

• Primary Productivity: The rate of biomass generation by producers (autotrophs).
• Secondary Productivity: The rate of biomass generation at the consumer level (heterotrophs).
• Comparative Productivity (Decreasing Order): Mangroves > Grasslands > Lakes > Oceans.

IV. Environmental Issues & Human Impact

A. Pollution

• Bioaccumulation & Biomagnification:
  • DDT is a persistent pollutant that does not break down easily.
  • Its concentration increases at each successive trophic level (biomagnification).
  • Top predators (like snakes) show the highest concentration.

B. Human Impact Concepts

• Ecological Footprint: Measures the amount of land required to sustain a person’s lifestyle (unit: Global Hectare – gha).
• Ecological Transition: A concept (first used by John W. Bennett) describing the shift to a human-centered view of the natural world.
• Interdependence: Components of an ecosystem are highly interdependent; a change in one affects others.
• Disturbances: Human activities like lumbering, overpopulation, pollution, deforestation, and fossil fuel burning disturb ecological balance.

V. Conservation & Policy

A. Conservation Movements

• Chipko Movement (1973): A non-violent protest in the Garhwal Himalayas where villagers hugged trees to prevent deforestation. Slogan: “Ecology is permanent economy.”
• Narmada Bachao Andolan: Opposed the construction of large dams on the Narmada River.
• Appiko Movement: An environmental movement in Karnataka.

B. Practices for Ecological Balance

• Promoting activities like water management, afforestation, and wildlife protection.
• Industrial management is not considered a direct activity for maintaining ecological balance.

C. Indian Environmental Laws

• Wildlife Protection Act: 1972
• Forest Conservation Act: 1980
• Environment Protection Act: 1986
• Scheduled Tribes and Other Traditional Forest Dwellers Act: 2006
• Eco-Sensitive Zones:
  • Declared under the Environment (Protection) Act, 1986.
  • Purpose is not to prohibit all human activities; activities like agriculture and rainwater harvesting are often permitted.

VI. Specific Ecosystems & Organisms

• Oceans: Considered the most stable ecosystem on Earth.
• Coral Reefs:
  • Found mostly in tropical waters.
  • Over one-third are in Australia, Indonesia, and the Philippines.
  • Host 32 out of 34 animal phyla, making them more diverse than tropical rainforests.
• Mangroves: Among the most productive ecosystems on Earth.
• Eucalyptus Trees: Not considered eco-friendly due to high water consumption, depleting water tables.

VII. Additional Concepts

A. Ecosystem Services

• Supporting Services: Indirect, long-term processes (e.g., nutrient cycling, soil formation, water cycling, crop pollination).
• Other categories: Provisioning, Regulating, and Cultural services.

B. Carbon Economics

• Social Cost of Carbon (SC-CO2): A monetary measure of the long-term damage done by a tonne of CO2 emissions.

C. Oceanography Terms

• Pycnocline: Layer where water density changes rapidly with depth.
• Halocline: Layer where salinity changes rapidly with depth.
• Thermocline: Layer where temperature changes rapidly with depth.

Know More About Ecology:

• Ecology – Old Year Questions
• Ecology One Liner Questions & Answers