Environmental Geography & Biogeography

Human-environment interactions, ecosystems, biogeography, pedology, and contemporary environmental challenges.

Author

Geography Team

Official Syllabus

NEP-2020 Syllabus

NoteCore I Paper V — Environmental Geography and Biogeography

**(4 Credit, Theory: 45hrs, Practical: 30hrs)*

**Unit I — Environment & Ecosystem*

  • Environment: Concept, Types, Characteristics and Principles
  • Environmental Controls and Concept of Tolerance
  • Ecosystem: Concept, Types, Structure and Functions (Food Chain, Food Web, Trophic Level, Ecological Pyramid)
  • Energy Flow in Ecosystem
  • Bio-geo-chemical Cycles (Nitrogen, Carbon, Oxygen)
  • Concept and Types of Biomes (Equatorial, Subtropical, Temperate and Polar)

**Unit II — Biogeography*

  • Introduction to Biogeography: Nature, Scope, Development
  • Ecological Succession: Succession, Change and Equilibrium
  • Key Processes in Biogeography: Evolution, Speciation, Extinction, Dispersal
  • World Distribution Patterns of Biota: Biogeographical Regions
  • Distribution of World’s Biodiversity Hotspots: Critical, Endangered, Threatened, Relatively Stable/Intact

**Unit III — Pedology (Soil Geography)*

  • Soil Colour, Soil Texture and Soil Structure
  • Soil Horizons
  • Soil Forming Processes and Factors
  • Soil Classification:
      1. By Maturity: Entisols, Inceptisols, Alfisols, Spodosols, Ultisols, Oxisols
      1. By Climate: Mollisols, Ardisols, Gelisols
      1. By Parent Material: Vertisols, Andisols

**Unit IV — Practical*

  1. Project Report on any environmental problem of global/national/local significance
  2. Seminar paper on biodiversity hotspots of India (distribution, biotic characteristics, major threats, solutions)
  3. Report and Viva-Voce

UGC NET Syllabus

TipUnit III — Oceanography and Bio-Geography (Bio-Geography Section)
  • Physical factors influencing world distribution of plants and animals
  • Forms and functions of ecosystems: Forest, Grassland, Marine, Mountain
  • Biodiversity and its depletion: natural and human-induced causes
  • Conservation and management of ecosystems
  • Environmental hazards and pollution
  • Ozone depletion

Environmental Geography (Paper II Topics)

  • Components: Ecosystem (Geographic Classification) and Human Ecology
  • Functions: Trophic Levels, Energy Flows, Cycles (geo-chemical, carbon, nitrogen, oxygen), Food Chain, Food Web and Ecological Pyramid
  • Human Interaction and Impacts, Environmental Ethics and Deep Ecology
  • Environmental Hazards and Disasters: Global Warming, Urban Heat Island, Atmospheric Pollution, Water Pollution, Land Degradation
  • National Programmes and Policies: Legal Framework, Environmental Policy, International Treaties, International Programmes and Policies (Brundtland Commission, Kyoto Protocol, Agenda 21, Sustainable Development Goals, Paris Agreement)

NET Environmental Geography — Detailed Syllabus (Pulakesh Pradhan)

ImportantSyllabus Topics (5 Questions = 10 Marks)
  • Physical factors influencing world distribution of plants and animals
  • Forms and function of ecosystem
  • Forest, grassland, mountain and marine ecosystem
  • Bio-diversity and its implications through natural and man-induced causes
  • Conservation and management of ecosystem
  • Environmental hazards and problems of pollution
  • Ozone Depletion

Most Important Topics for Exam (NET Notes)

TipHigh-Yield Topics
  1. Types of forest — Selva / plants important
  2. Ecosystem — marine, components
  3. Soil formation — saline
  4. Region and forest
  5. No. of flora and fauna in forests — names
  6. Synecology & Ecology
  7. Important Environmental Days
  8. Tsunami, earthquake, flood
  9. Laws and Acts — Millennium Ecosystem Assessment, Conferences
  10. Biosphere, National Park, Sanctuary
  11. Types of plants — xerophyte, mesophyte, heliothermal, evergreen, coniferous
  12. Distribution of Grassland / Plants — vegetation belts
  13. Ecological Pyramid, Food Chain and Food Web
  14. Bio-diversity & Carbon Sink
  15. Biome, Rainforest
  16. Bio-geographic Region
  17. Emitters and Emitter Products

Welcome to the Environmental Geography & Biogeography module of Geography OpenCourseWare. This course bridges physical and human geography by examining the complex interactions between human societies and the natural environment — from ecosystem dynamics and biogeography to soil science and contemporary environmental crises.

Part A: Common Topics (NEP-2020 & UGC NET)

These topics are covered in both the NEP-2020 undergraduate syllabus and the UGC NET syllabus. The content below highlights syllabus-specific divisions for each topic.

Environment: Concept, Types, and Characteristics

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Syllabus Topic Details
NEP-2020 Unit I — Environment: Concept, Types, Characteristics and Principles
UGC NET Ecosystem Components (Geographic Classification)

The environment encompasses the totality of physical, chemical, and biological conditions surrounding an organism. Understanding the concept, types, and principles of the environment forms the foundation of environmental geography.

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NoteKey Concepts
  • Definition of Environment: The sum total of all conditions and influences that affect the life and development of organisms — natural and human-made.
  • Types of Environment:
    • Natural Environment: Lithosphere, Hydrosphere, Atmosphere, Biosphere
    • Human-made Environment: Built environment, cultural landscape, industrial zones
    • Social Environment: Institutions, norms, and socio-economic structures
  • Characteristics of Environment: Dynamic, interactive, holistic, and spatially variable.
  • Principles of Environmental Geography: Principle of interrelationship, principle of diversity, principle of sustainability.
  • Environmental Determinism vs. Possibilism: The debate on how environment shapes human activity.

Ecosystem: Structure and Functions

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Syllabus Topic Details
NEP-2020 Unit I — Ecosystem: Concept, Types, Structure and Functions (Food Chain, Food Web, Trophic Level, Ecological Pyramid)
UGC NET Functions: Trophic Levels, Energy Flows, Food Chain, Food Web and Ecological Pyramid; Forms and functions of ecosystems

An ecosystem is a functional unit of nature where living organisms interact with each other and with the surrounding physical environment.

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NoteEcosystem Fundamentals
  • Concept of Ecosystem: Coined by A.G. Tansley (1935) — a self-sustaining, structural and functional unit of the biosphere. The structure and function of living systems are maintained by chemical, physical, and organic activities known as Homeostatic mechanisms.
  • Types of Ecosystems: Terrestrial (forest, grassland, desert, tundra), Aquatic (freshwater, marine, estuarine), and Artificial (agro-ecosystem, urban).
  • Ecosystem Structure:
    • Biotic Components: Producers, Consumers (herbivores, carnivores, omnivores), Decomposers (saprotrophs)
      • Photo autotrophs: Obtain energy from photosynthesis.
      • Chemo autotrophs: Obtain energy from oxidation of compounds.
      • Zymogenous organisms: Proliferate rapidly in the presence of an organic substrate.
      • Facultative organisms: Can adapt to the presence or absence of oxygen.
    • Abiotic Components: Climate, soil, water, light, nutrients.
      • Tropophytes: Plants that behave as a xerophyte in one season and as a hydrophyte in another (e.g., deciduous trees).
  • Food Chain: Linear sequence of energy transfer — grazing chain, detritus chain.
  • Food Web: Complex, interconnected network of multiple food chains in an ecosystem.
  • Trophic Levels: Producers (T1), Primary consumers (T2), Secondary consumers (T3), Tertiary consumers (T4).
  • Ecotone: A transition zone between two different ecosystems. It can be depicted through a quantitative method as an Intersection Set.
  • Ecological Pyramids:
    • Pyramid of Numbers (Elton)
    • Pyramid of Biomass
    • Pyramid of Energy (always upright)

Ecosystem — Detailed Concepts (NET Notes — Pulakesh Pradhan)

Ecosystem = functional unit of environment (producer–consumer–decomposer relationship)

Key Definitions

Term Definition
Environment Everything in a region
Habitat Area where an organism lives
Biosphere Region on Earth that supports life = Lithosphere + Hydrosphere + Atmosphere
Ecology From Greek Oikos (home) + logos (study)
Biome A large naturally occurring community of flora & fauna
Ecotone Transition zone between two biomes (e.g., mangrove)
Edge Effect / Edge Species Species found at the ecotone zone
Ecological Niche Unique functional role of a species in its habitat; no two species share the same niche
Vermin Species that increase rapidly

Ecological Hierarchy

Individual → Population → Community → Ecosystem → Biome → Biosphere

Energy Flow in Ecosystem

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Syllabus Topic Details
NEP-2020 Unit I — Energy Flow in Ecosystem
UGC NET Functions: Energy Flows, Trophic Levels

Energy flow is the passage of energy through the various trophic levels of an ecosystem — it is unidirectional and follows the laws of thermodynamics.

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NoteEnergy Flow Concepts
  • Solar Radiation: The primary source of energy — only ~1-2% is captured by photosynthesis. About 50% of incoming solar radiation is Photosynthetically Active Radiation (PAR), but only a meagre quantity (2–10%) of PAR is used in primary production. In deep-sea hydrothermal ecosystems, the initial source of energy is not solar radiation.
  • Laws of Thermodynamics: First law (energy conservation) and second law (entropy) govern energy transfer.
  • Gross Primary Productivity (GPP): Total organic matter produced by autotrophs through photosynthesis.
  • Net Primary Productivity (NPP): GPP minus respiration losses — the energy available to consumers.
  • 10% Rule (Lindeman’s Law): Coined by R. Lindeman, it states that only about 10% of energy is transferred from one trophic level to the next.
  • Ecological Efficiency: The ratio between the energy flow at different trophic levels along the food chain, when expressed as a percentage.
  • Energy Flow Models:
    • Single-channel energy flow model
    • Y-shaped energy flow model (grazing + detritus pathways)
  • Biomass Pyramid: In a terrestrial ecosystem, the biomass is about 90–99% less at each higher trophic level.
  • Significance: Explains ecosystem productivity, trophic efficiency, and limits on food chain length.

Trophic Levels & Energy Flow (NET Notes — Pulakesh Pradhan)

‘Trophe’ = Nutrient Energy decreases from first to last trophic level

Trophic Levels

Level Organism Food Source
1st TL Producers Own food (plants, algae)
2nd TL Herbivores Eat producers
3rd TL Carnivores Eat secondary consumers
4th TL Carnivores Eat other carnivores
  • A. Raymond Lindeman (1942) — gave the concept of Trophic Level
  • August Thienemann (1926) — coined ‘producer’ & ‘consumer’

Bio-geo-chemical Cycles

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Syllabus Topic Details
NEP-2020 Unit I — Bio-geo-chemical Cycles (Nitrogen, Carbon, Oxygen)
UGC NET Cycles: geo-chemical, carbon, nitrogen and oxygen

Biogeochemical cycles are the pathways through which essential chemical elements (nutrients) circulate between biotic and abiotic components of the ecosystem.

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NoteMajor Biogeochemical Cycles
  • Carbon Cycle: Photosynthesis → Respiration → Decomposition → Combustion. Carbon reservoirs: atmosphere (CO₂), oceans, fossil fuels, biomass. Human perturbation through fossil fuel burning.
  • Nitrogen Cycle: Nitrogen fixation (biological, atmospheric, industrial) → Nitrification → Assimilation → Ammonification → Denitrification. Role of Rhizobium, Azotobacter. Note: Nitrogen is not more abundant in living organisms than carbon, hydrogen, and oxygen.
    • Nitrogen fixation: Nitrogen is converted to ammonia.
    • Nitrification: NH₄⁺ is converted to NO₃⁻.
    • Denitrification: Bacteria use NO₃⁻ for metabolism.
  • Oxygen Cycle: Photosynthesis (O₂ release), respiration (O₂ consumption), ozone formation and depletion.
  • Types of Cycles:
    • Gaseous Cycles: Carbon, nitrogen, oxygen — reservoir in atmosphere/hydrosphere
    • Sedimentary Cycles: Phosphorus, sulphur — reservoir in lithosphere. Phosphorus has the slowest rate of turnover with respect to its residence time in the lithosphere.
  • Hydrological Cycle: Evaporation → Condensation → Precipitation → Runoff → Infiltration — links all biogeochemical cycles.
  • Human Impact: Eutrophication (excess nitrogen/phosphorus), acidification, greenhouse gas enhancement.

Biomes: Concept and Types

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Syllabus Topic Details
NEP-2020 Unit I — Concept and Types of Biomes: Equatorial, Subtropical, Temperate and Polar
UGC NET Forms and functions of ecosystems: Forest, Grassland, Marine, Mountain

A biome is a large-scale biotic community characterized by dominant vegetation types and adapted animal life, shaped primarily by climate.

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NoteNEP-2020 Classification (Climate-based)
  • Equatorial Biome: Tropical evergreen rainforests — high temperature, heavy rainfall (>200 cm rainfall, 15–30°C), greatest biodiversity (Amazon, Congo, Southeast Asia).
  • Subtropical Biome: Savanna, Mediterranean — seasonal rainfall, dry winters or dry summers.
  • Temperate Biome: Deciduous and mixed forests, grasslands (prairies, steppes) — moderate climate with four distinct seasons. Teak and Sal are the most dominant species in Tropical Deciduous Forests.
  • Polar Biome: Tundra and ice caps — extreme cold, permafrost, limited vegetation (lichens, mosses).
  • Desert Vegetation: Leaf modifications like hard and waxy leaves, tiny leaves or no leaves, and thorns instead of leaves are adaptations in desert areas to inhibit water loss.
TipUGC NET Classification (Ecosystem-based)
  • Forest Ecosystems: Tropical, temperate, and boreal forests — structure, stratification, productivity.
  • Grassland Ecosystems: Tropical (savanna), temperate (prairies, steppes, pampas) — role of fire and grazing.
  • Marine Ecosystems: Coral reefs, estuaries, deep sea, continental shelves — marine productivity zones.
  • Mountain Ecosystems: Altitudinal zonation, alpine meadows, fragile ecology — climate change vulnerability.

Biomes — Detailed Classification (NET Notes — Pulakesh Pradhan)

I.G. Simmons (1982): *“The most extensive ecosystem unit which it is convenient to designate is called Biome”

1. Tropical Evergreen Forest (Selva)

  • High rainfall + high temperature throughout the year
  • Latitude: 10°N to 10°S
  • Regions: Amazon Basin, Congo Basin, Indo-Malaysian region
  • 6000–7000 species of plants; 20,000 species of flowering plants (70% of total tropical evergreen)
  • Vertical Strata: 1st (Dominant: 20-60m), 2nd (Codominant: 25-30m), 3rd (15-20m), 4th (Herbaceous: 5m), 5th (Ground).

2. Monsoon Deciduous Forest

  • Regions: Neotropics (West Indies), Indo-Malaysian Zone, Eastern Africa & Northern Australia
  • Rainfall: 150 cm; Main trees: Sal, Teak, Bamboo (Jhum cultivation practiced).

3. Savanna Biome (Aw Climate)

  • Dominant xeromorphic herbaceous plants (African elephant grass).
  • Regions: Llanos (Colombia/Venezuela), South-Central Brazil, Guiana.
  • Animals: Marsupials (South America). No competition among animals here.
  • A.F. Lamprey divided savanna biome into 5 categories.

4. Mediterranean Biome

  • Also called Sclerophyll ecosystem / biome (Dry summer, wet winter).
  • Latitude: 30° to 40°/45°N.
  • Local Names: Maquis (S. Europe), Chaparral (California), Fynbos (S. Africa), Mallee Scrub (Australia).

5. Temperate Grassland Biome

  • Located in interior of continents (Climax community species).
  • Regional Names: Steppes (Eurasia), Prairies (N. America), Pampas (S. America), Downs (Australia), Canterbury (New Zealand), Veld (Africa).
  • ‘Dust Bowl’ — extensive cultivation of semi-arid prairie regions of Great Plains, USA.

6. Taiga / Boreal Forest (Temperate Coniferous)

  • Siberian type of climate; Temperature below 0°C for 6+ months.
  • Regions: Sub-arctic N. America, Scandinavia to Russian Siberia. Hardwood/broad-leaved deciduous trees; Caribou & moose.

7. Tundra Biome

  • Mean annual temp < 0°C; Lithosols (lichens and mosses).
  • Tribes: Eskimos, Samoyeds.

8. Marine Biome

  • 2/3 of the total area of biomes. Up to 200 metres = Photic Zone.

Biodiversity and its Depletion

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Syllabus Topic Details
NEP-2020 Unit II — Distribution of World’s Biodiversity Hotspots: Critical, Endangered, Threatened, Relatively Stable/Intact
UGC NET Biodiversity and its depletion: natural and human-induced causes

Biodiversity — the variety of life at genetic, species, and ecosystem levels — is the foundation of ecosystem services and human well-being. Its depletion poses one of the greatest environmental challenges.

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NoteNEP-2020 Focus: Biodiversity Hotspots
  • Concept of Biodiversity Hotspots: Coined by Norman Myers (1988) — regions with high endemism and significant habitat loss.
  • Global Hotspots: 36 recognized hotspots covering just 2.5% of Earth’s land surface but harboring >50% of plant species.
  • Indian Hotspots: Western Ghats–Sri Lanka, Eastern Himalayas, Indo-Burma, Sundaland.
  • Special Ecosystem Phenomena:
    • Darwin’s Paradox: The sustenance of an ecosystem with an abundance of marine life in apparently nutrient-free and clear water of the coral reefs.
    • Helophytes: Plants that grow specifically in marshes.
  • Conservation Status Categories:
    • Critical: Imminent risk of extinction
    • Endangered: Very high risk of extinction in the wild
    • Threatened: Vulnerable to becoming endangered
    • Relatively Stable/Intact: Low current risk but requiring monitoring
TipUGC NET Focus: Causes of Depletion
  • Natural Causes: Natural disasters, climatic fluctuations, evolutionary dead ends, disease outbreaks.
  • Human-Induced Causes:
    • Habitat Destruction: Deforestation, urbanization, agricultural expansion
    • Overexploitation: Overhunting, overfishing, illegal wildlife trade
    • Pollution: Pesticides, industrial effluents, plastic contamination
    • Invasive Species: Introduction of alien species disrupting native ecosystems
    • Climate Change: Shifting habitats, phenological mismatches. Coral bleaching occurs when zooxanthellae are damaged by intense ultraviolet radiation, xenobiotic contaminants, alteration of ocean salinity & temperature, and intense sedimentation.
  • IUCN Red List: The global standard for assessing species extinction risk.
  • Sixth Mass Extinction: Anthropocene biodiversity crisis — current extinction rates 100–1000x background rates.

World Biodiversity Statistics (NET Notes — Pulakesh Pradhan)

  • India has 10 bio-geographic regions contributing **7–8% of world biodiversity*
  • ‘Biodiversity Hotspot’ — concept given by **Norman Myers*

India’s Biodiversity Profile

Category Count / Percentage
Species of plants 45,500
Species of animals 91,000
Mangrove 2.4%
Mammals 12.6%
Birds 4.5%
Reptiles 45.8%
Amphibians 55.8%

Environmental Hazards and Pollution

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Syllabus Topic Details
NEP-2020 Related concepts across units
UGC NET Environmental Hazards and Disasters: Global Warming, Urban Heat Island, Atmospheric Pollution, Water Pollution, Land Degradation; Environmental hazards and pollution

Environmental hazards encompass natural and human-induced events that threaten ecosystems and human well-being. Pollution involves the introduction of harmful substances into the environment.

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NoteEnvironmental Hazards
  • Global Warming: Enhanced greenhouse effect, rising global temperatures, sea-level rise, ice sheet melting.
  • Ozone Depletion: The ozone hole centers on polar regions because during the dark austral winter, ozone along with destructive pollutants (CFCs and NOx) are trapped in the circum-polar vortex. In the austral spring, this ozone is destroyed.
  • Urban Heat Island (UHI): Cities significantly warmer than surrounding rural areas — causes, impacts, mitigation.
  • Natural Hazards: Earthquakes, volcanic eruptions, floods, cyclones, droughts, landslides. Flood is the most destructive natural hazard in the Ganga-Brahmaputra plains, where population pressure forces many people to live in flood-prone areas.
ImportantPollution
  • Atmospheric Pollution: Sources (vehicular, industrial, biomass burning), types of pollutants (SOx, NOx, CO, PM2.5, PM10, VOCs). Note that Arsenopyrite is a mineral and not an air pollutant. Automobile Industries are the main source of Carbon Monoxide (CO) pollution by human practices.
    • National Ambient Air Quality Standards (NAAQS): Includes pollutants like Lead, which is not included in the regular National Air Quality Index (AQI).
    • Smog Types: London smog (high concentration of SO₂), Photochemical smog (volatile organic compounds/VOC).
  • Water Pollution: Point and non-point source pollution, eutrophication, groundwater contamination, marine pollution. The maximum permissible limit set by the Bureau of Indian Standards (BIS) for nitrate level in drinking water is 45 mg/l.
  • Dam and Hydroelectric Impacts: While providing economic progress, hydroelectric power creates serious ecological problems:
    • Large areas of forest and agricultural land are submerged.
    • Silting of reservoirs reduces the lifespan of installations.
    • Use of rivers for navigation and fisheries becomes difficult.
    • Resettlement of displaced persons is a very serious and difficult issue.
  • Land Degradation: Soil erosion, desertification, salinization, waterlogging, loss of soil fertility.
  • Noise Pollution: Sources, health impacts, regulatory standards.
  • Impact Assessment: Environmental Impact Assessment (EIA), pollution indices, monitoring networks. EIA was first introduced in the U.S.A. (NEPA, 1969). A notable qualitative environmental assessment method developed in 1971 by the USGS is the Leopold Matrix.
  • Pollution Management:
    • Principles: The principles of managing water and air pollution rest on Dilution and Concentration.
    • Waste-water Treatment:
      • Primary: Physical separation (e.g., using a Comminutor).
      • Secondary: Biological treatment (e.g., using Activated sludge).
      • Tertiary: Chemical/Physical refinement (e.g., Disinfection).
    • Bio-accumulation: The presence of trace elements in the human body (e.g., Arsenic traces) is an example of Bio-accumulation.

Conservation and Management of Ecosystems

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Syllabus Topic Details
NEP-2020 Related to biodiversity conservation concepts (Unit II)
UGC NET Conservation and management of ecosystems

Conservation of ecosystems involves the sustainable management, protection, and restoration of natural habitats and biodiversity for present and future generations.

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NoteConservation Approaches
  • In-situ Conservation: Protection of species in their natural habitats.
    • National Parks, Wildlife Sanctuaries, Biosphere Reserves
    • Sacred Groves, Community Reserves
    • Protected Area Network — IUCN Categories I–VI
  • Ex-situ Conservation: Protection of species outside their natural habitats.
    • Zoological gardens, Botanical gardens
    • Seed banks, Gene banks, Cryopreservation
  • Conservation Strategies:
    • Wildlife Protection Act (1972)
    • Biodiversity Act (2002)
    • Convention on Biological Diversity (CBD)
    • CITES (Convention on International Trade in Endangered Species)
  • Ecosystem Management:
    • Watershed management
    • Joint Forest Management (JFM)
    • Wetland conservation (Ramsar Convention)
    • Coral reef conservation and marine protected areas
    • Ecosystem Restoration: Associated with introducing native plants, dam decommissioning, and restricting grazing (it is not directly associated with restricting anthropogenic control entirely, as restoration itself is often anthropogenic).
    • Soil Erosion Assessment Methods: Models like RUSLE, PESERA, and CORINE are used to assess erosion risk.
  • Carbon Sequestration: In a stable climate, forests generally sequester more carbon than grasslands because they store most of their carbon in above-ground woody biomass.
  • Community-based Conservation: Role of indigenous communities, traditional ecological knowledge.

Part B: NEP-2020 Specific Topics

These topics are part of the NEP-2020 undergraduate programme only.

Biogeography (Unit II)

Environmental Controls and Concept of Tolerance

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Syllabus Topic Details
NEP-2020 Unit I — Environmental Controls and Concept of Tolerance

Environmental controls determine the distribution and abundance of organisms, while the concept of tolerance defines the range of environmental conditions within which an organism can survive.

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NoteKey Concepts
  • Environmental Controls: Factors that regulate the distribution and growth of organisms — temperature, moisture, light, soil, topography.
  • Shelford’s Law of Tolerance (1913): Every organism has a minimum, maximum, and optimum range for each environmental factor.
    • Stenothermal: Narrow temperature tolerance (e.g., coral reefs)
    • Eurythermal: Wide temperature tolerance (e.g., humans)
    • Stenohaline / Euryhaline: Narrow / wide salinity tolerance
  • Liebig’s Law of the Minimum (1840): Growth is limited by the resource in shortest supply, not the total amount of resources.
  • Limiting Factors: The environmental factor closest to the tolerance limit of an organism becomes the controlling factor.
  • Ecological Amplitude: The range of environmental conditions tolerated by a species — determines its niche breadth.
  • Ecotone and Edge Effect: Transition zones between two ecosystems often show greater species diversity.

Introduction to Biogeography: Nature, Scope, Development

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NEP-2020 Unit II — Introduction to Biogeography: Nature, Scope, Development

Biogeography is the study of the spatial distribution of organisms and the processes that produce these distribution patterns across time and space.

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NoteNature, Scope, and Development
  • Definition: Biogeography studies the geographic distribution of plants (phytogeography) and animals (zoogeography) and the factors that determine these distributions.
  • Nature: Interdisciplinary — bridges biology, ecology, geography, geology, climatology, and evolutionary biology.
  • Scope:
    • Spatial patterns of biodiversity
    • Historical and ecological explanations for distribution
    • Conservation biogeography
    • Island biogeography
    • Paleobiogeography
  • Historical Development:
    • Pre-Darwinian: Linnaeus, Buffon (Buffon’s Law), Alexander von Humboldt
    • Darwinian Era: Charles Darwin, Alfred Russel Wallace (“Father of Zoogeography”)
    • Modern Era: MacArthur & Wilson (Island Biogeography Theory, 1967), Conservation biogeography
  • Branches:
    • Historical Biogeography: Explains distribution through plate tectonics, vicariance, and dispersal events
    • Ecological Biogeography: Focuses on current environmental controls on species distribution

Ecological Succession

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NEP-2020 Unit II — Ecological Succession: Succession, Change and Equilibrium

Ecological succession is the orderly and predictable process of community change over time in a given area, moving towards a relatively stable climax community.

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NoteSuccession Concepts
  • Definition: Sequential replacement of one community by another in an area until a stable (climax) community is established.
  • Types of Succession:
    • Primary Succession: Begins on bare, lifeless substrate (e.g., lava flows, exposed rock). The process is completed in sequential steps: Nudation → Invasion → Competition → Reaction → Stabilisation.
    • Secondary Succession: Begins in areas where a previous community has been disturbed (e.g., abandoned farmland, forest fire areas). Faster than primary succession.
  • Ecesis: The successful establishment of a plant or animal species in a new habitat.
  • Seral Stages: Each intermediate community in the succession is called a sere or seral stage.
    • Hydrosere (aquatic succession)
    • Xerosere (dry land succession)
    • Lithosere (bare rock succession)
    • Psammosere (sand succession)
  • Climax Community: The final, stable, self-perpetuating community in equilibrium with the environment.
    • Monoclimax Theory (Clements): Only one climax community per climate region.
    • Polyclimax Theory (Tansley): Multiple climax communities possible based on local factors.
  • Change and Equilibrium: Dynamic equilibrium — ecosystems constantly adjust to disturbances while maintaining overall stability.
  • Retrogressive Succession: Reversal of succession due to environmental degradation (overgrazing, deforestation).

Key Processes in Biogeography

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NEP-2020 Unit II — Key Processes in Biogeography: Evolution, Speciation, Extinction, Dispersal

The distribution of life on Earth is shaped by four fundamental biogeographic processes — evolution, speciation, extinction, and dispersal.

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NoteBiogeographic Processes
  • Evolution: Gradual change in heritable characteristics of biological populations over generations. Natural selection (Darwin), genetic drift, mutation, gene flow.
  • Speciation: Formation of new and distinct species through evolutionary processes.
    • Allopatric Speciation: Geographic isolation (e.g., continental drift, mountain barriers)
    • Sympatric Speciation: Speciation without geographic isolation (e.g., ecological or behavioral divergence)
    • Parapatric Speciation: Occurs in adjacent populations with partial geographic overlap
  • Extinction: Permanent disappearance of a species from all habitats.
    • Background Extinction: Normal rate of species loss over geological time
    • Mass Extinction: Rapid loss of large number of species (e.g., Permian-Triassic, Cretaceous-Paleogene)
    • Anthropogenic Extinction: Human-caused — habitat destruction, overexploitation, climate change
  • Dispersal: Movement and spread of organisms from their place of origin to new areas.
    • Jump Dispersal: Long-distance movement across barriers (rare, colonization events)
    • Diffusion: Gradual expansion of range over generations
    • Secular Migration: Slow dispersal over evolutionary time (geological epochs)
    • Barriers to dispersal: Oceans, mountains, deserts, climate zones

Biogeographical Regions

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NEP-2020 Unit II — World Distribution Patterns of Biota: Biogeographical Regions

Biogeographical regions are large areas of the Earth’s surface characterized by distinct assemblages of plants and animals shaped by evolutionary history, plate tectonics, and climate.

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NoteZoogeographic Regions (Wallace’s Realms)
  • Palaearctic: Europe, North Africa, northern Asia — temperate fauna, limited endemism.
  • Nearctic: North America — closely related to Palaearctic (Holarctic connection), bison, pronghorn.
  • Neotropical: Central and South America — highest biodiversity, unique endemic fauna (sloths, armadillos, New World monkeys).
  • Ethiopian (Afrotropical): Sub-Saharan Africa — megafauna (elephants, giraffes, great apes), high endemism.
  • Oriental (Indo-Malayan): South and Southeast Asia — tigers, Asian elephants, orangutans.
  • Australasian: Australia, New Zealand, Pacific Islands — marsupials, monotremes (platypus), ratite birds.
TipFloristic Kingdoms
  • Boreal (Holarctic) — Largest, covers Europe, North Asia, North America
  • Palaeotropical — Tropical Africa, South & Southeast Asia
  • Neotropical — Central and South America
  • South African (Cape) — Smallest, extremely rich in endemic flora (fynbos)
  • Australian — Eucalyptus, Acacia, high endemism
  • Antarctic — Southern tip of South America, subantarctic islands

World Distribution of Plants (Floristic Kingdoms) (NET Notes)

Floristic Kingdom — a larger group of plants occupying almost the same environmental conditions

  1. Australian Region: 600 species; Eucalyptus dominant (75% mass).
  2. Cape Region: Southern tip of Africa; cryptophytes (survive unfavourable conditions); Laplia, Erica, Freesia.
  3. Antarctic Region: Patagonia to New Zealand; Tussock grass, Gymnosperms (NZ).
  4. Palaeotropical Region: Africa, SW/S/SE Asia, S/M China.
  5. Neotropical Region: South America (except south). Separated by Gondwanaland spreading.
  6. Boreal Region: Most extensive kingdom (N. America, Europe, N. Asia, Arctic).

World Distribution of Animals (Zoogeographical Regions) (NET Notes)

Development of animal zones in higher latitudes due to dispersal and migration. A.R. Wallace — defined 6 Faunal Regions.

Wallace’s Faunal Regions

No. Region Area
1 Palaearctic Europe and North Asia
2 Nearctic North America & Greenland
3 Oriental North & South-East Asia & W. Africa
4 Ethiopian Whole Africa, Sahara and beyond
5 Australian Australia + New Zealand
6 Neotropical South America

Pedology — Soil Geography (Unit III)

Soil: Colour, Texture, and Structure

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NEP-2020 Unit III — Soil Colour, Soil Texture and Soil Structure

Soil physical properties — colour, texture, and structure — are fundamental characteristics that determine soil behaviour, fertility, and classification.

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NoteSoil Physical Properties
  • Soil Colour:
    • Determined using the Munsell Colour Chart (Hue, Value, Chroma)
    • Dark/Black: High organic matter content (humus)
    • Red/Yellow: Iron oxides (laterization)
    • White/Grey: Leached horizons, calcium carbonate, silica
    • Mottled: Indicates fluctuating water tables (gleying)
  • Soil Texture:
    • Relative proportions of sand, silt, and clay particles
    • Textural Triangle: Classification into sandy, loamy, clayey, and intermediate classes
    • Importance: Determines water-holding capacity, permeability, aeration, and nutrient retention
    • Feel Test: Field method to estimate texture
  • Soil Structure:
    • Arrangement of soil particles into aggregates (peds)
    • Types: Granular, blocky, prismatic/columnar, platy, single grain, massive
    • Importance: Influences root penetration, water infiltration, and soil aeration
    • Factors: Organic matter, clay content, biological activity, wetting-drying cycles

Soil Horizons

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NEP-2020 Unit III — Soil Horizons

Soil horizons are distinct layers within a soil profile, each with characteristic physical, chemical, and biological properties developed through pedogenesis.

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NoteSoil Horizon Classification
  • O Horizon (Organic layer): Surface layer of organic matter — leaf litter, humus, decomposing material.
  • A Horizon (Topsoil): Rich in organic matter mixed with mineral particles; zone of maximum biological activity; dark coloured.
  • E Horizon (Eluviation zone): Leached layer — loss of clay, iron, aluminium through percolating water; lighter in colour.
  • B Horizon (Subsoil / Illuviation zone): Zone of accumulation — clay, iron oxides, calcium carbonate deposited from above; often reddish-brown.
  • C Horizon (Parent material): Partially weathered parent material — bedrock fragments; little biological activity.
  • R Horizon (Bedrock): Unweathered consolidated rock underlying the soil.
  • Soil Profile: Vertical cross-section of soil from surface to bedrock showing all horizons.
  • Diagnostic Horizons:
    • Epipedons: Surface horizons (mollic, ochric, umbric)
    • Subsurface horizons: Argillic, spodic, oxic, calcic
  • Significance: Horizon development indicates soil maturity, climate, and land use history.

Soil Forming Processes and Factors

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NEP-2020 Unit III — Soil Forming Processes and Factors

Soil formation (pedogenesis) is the result of complex interactions between parent material, climate, organisms, topography, and time — the five soil-forming factors identified by Hans Jenny.

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NoteJenny’s Five Soil-Forming Factors (CLORPT)
  • Climate (Cl): Temperature and precipitation control weathering rates, organic matter decomposition, and leaching intensity.
  • Organisms (O): Plants, animals, microorganisms, and humans contribute organic matter, mix soil, and influence nutrient cycling.
  • Relief/Topography (R): Slope angle, aspect, and elevation affect drainage, erosion, soil depth, and microclimate.
  • Parent Material (P): Bedrock or unconsolidated deposits determine soil texture, mineral composition, and initial pH.
  • Time (T): Duration of soil formation — young soils (Entisols) vs. highly weathered soils (Oxisols).
TipSoil-Forming Processes
  • Additions: Organic matter, dust, volcanic ash deposited on or into soil.
  • Losses (Removals): Erosion, leaching, harvesting — removal of materials from the profile.
  • Translocations: Movement of materials within the profile — eluviation (loss from upper horizons) and illuviation (gain in lower horizons).
  • Transformations: Chemical and physical changes — weathering of minerals, decomposition of organic matter.
  • Specific Processes:
    • Laterization: Tropical weathering — accumulation of iron and aluminium oxides
    • Podzolization: Acidic leaching — removal of iron and aluminium from A horizon
    • Calcification: Accumulation of calcium carbonate in B horizon (arid/semi-arid regions)
    • Gleization: Reduction of iron under waterlogged conditions — grey/blue mottled soils
    • Salinization: Accumulation of soluble salts in arid soils

Soil Classification

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NEP-2020 Unit III — Soil Classification: (a) By Maturity (Entisols, Inceptisols, Alfisols, Spodosols, Ultisols, Oxisols), (b) By Climate (Mollisols, Ardisols, Gelisols), (c) By Parent Material (Vertisols, Andisols)

Soil classification provides a systematic framework for understanding, comparing, and mapping soils based on their properties, formation processes, and environmental context. The terms ‘Pedocals’ and ‘Pedalfers’ were first proposed by C.F. Marbut.

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Note(a) Classification by Maturity
  • Entisols: Youngest soils — minimal horizon development, recently deposited material (alluvial, volcanic).
  • Inceptisols: Slightly developed soils — weak B horizon, early stages of pedogenesis.
  • Alfisols: Moderately weathered — clay-rich B horizon (argillic), base-rich, fertile. Found in deciduous forest regions.
  • Spodosols: Highly leached — spodic B horizon enriched with iron, aluminium, and organic matter. Coniferous forest soils.
  • Ultisols: Intensely weathered — low base saturation, acidic, clay-rich. Subtropical/tropical humid regions.
  • Oxisols: Most weathered soils — deep, highly weathered, dominated by iron/aluminium oxides. Tropical regions.
Tip(b) Classification by Climate
  • Mollisols: Grassland soils — thick, dark, organic-rich A horizon (mollic epipedon). High fertility. Prairies and steppes.
  • Aridisols: Desert soils — low organic matter, often with calcic or salic horizons. Limited leaching due to aridity.
  • Gelisols: Permafrost soils — underlain by permanently frozen ground. Tundra and polar regions. Cryoturbation features.
Important(c) Classification by Parent Material
  • Vertisols: Clay-rich soils — high shrink-swell capacity (montmorillonite). Deep cracks in dry season. Black cotton soils of India (Regur).
  • Andisols: Volcanic soils — developed from volcanic ash and pumice. High water retention, low bulk density. Very fertile.

Part C: UGC NET Specific Topics

These topics are part of the UGC NET syllabus only.

Bio-Geography

Physical Factors Influencing World Distribution of Plants and Animals

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UGC NET Unit III — Physical factors influencing world distribution of plants and animals

The global distribution of flora and fauna is governed by a complex interplay of physical environmental factors including climate, topography, soil, and water availability.

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NoteKey Physical Factors
  • Climate:
    • Temperature: Determines latitudinal zonation — tropical, temperate, polar distributions.
      • **Vegetation Classes (by Temperature):*
        • Megatherms: Tropical Rainforest (high temperature year-round).
        • Mesotherms: Tropical Deciduous (alternating warm/cool).
        • Microtherms: Mixed coniferous (low temperature).
        • Hekistotherms: Alpine (extreme cold).
    • Precipitation: Controls vegetation density — forests in humid areas, deserts in arid zones
    • Light: Photoperiod affects flowering, migration, and hibernation patterns
    • Wind: Dispersal of seeds, spores; tree-line formation in exposed areas
  • Topography:
    • Altitude: Altitudinal zonation mirrors latitudinal zonation (vertical biomes)
    • Aspect: North vs. south-facing slopes — insolation differences affect species composition
    • Slope: Gradient affects drainage, soil depth, and erosion
  • Soil:
    • Soil type, pH, nutrient content, and moisture determine plant communities
    • Edaphic factors create specialized habitats (calcicole vs. calcifuge species)
  • Water:
    • Freshwater availability, salinity gradients, ocean currents
    • Aquatic vs. terrestrial habitat differentiation
  • Barriers and Corridors:
    • Mountains, oceans, and deserts act as barriers to dispersal
    • Land bridges and river valleys serve as corridors (e.g., Bering Land Bridge, Isthmus of Panama)
  • Continental Drift: Historical plate movements explain disjunct distributions and endemism.
  • **Bird Sanctuaries:*
    • Sultanpur: Haryana
    • Bharatpur: Rajasthan
    • Nawabganj: Uttar Pradesh
    • Ranganthithu: Karnataka
  • Green Data Book: Contains a list of rare plant species growing in protected areas like botanical gardens.

Types of Plants — Ecological Classification (NET Notes)

Plant Type Adaptation
Hydrophytes Adopted to aquatic environment (e.g., lotus)
Mesophytes Adopted to average water and temp; well-developed root system
Xerophytes Adopted to dry habitat
Cryptophytes Survive unfavourable/hostile conditions
Cryptozoic animals Live beneath stones, logs, dead branches

Vegetation Zones (by Temperature)

Zone Temperature
Megathermal Equatorial — high temperature year round
Xenophytic Dry / arid zone
Mesothermal 18°C to −3°C
Microthermal Coldest month below −3°C
Hekistothermal Tundra — lichens and mosses

Life Forms

  • Christen Raunkiær (1934) — first gave the concept of life forms.

Human Ecology & Environmental Ethics

Human Ecology

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UGC NET Components: Ecosystem (Geographic Classification) and Human Ecology

Human ecology studies the relationships between human societies and their natural, social, and built environments — how humans adapt to, modify, and are influenced by their surroundings.

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NoteHuman Ecology Concepts
  • Definition: The interdisciplinary study of the dynamic interactions between human populations and their physical, biological, and social environment.
  • Human-Environment Relationships:
    • Environmental Determinism: Environment shapes human culture and development (Ratzel, Semple)
    • Possibilism: Humans choose from environmental possibilities (Vidal de la Blache)
    • Neo-determinism / Stop-and-Go Determinism: Balance between determinism and possibilism (Griffith Taylor)
  • Ecological Adaptations:
    • Physiological adaptations (altitude, cold, heat)
    • Cultural adaptations (clothing, shelter, food systems)
    • Technological adaptations (irrigation, heating, air conditioning)
  • Carrying Capacity: Maximum population an environment can sustain without degradation.
  • Ecological Footprint: Measure of human demand on Earth’s ecosystems — biocapacity vs. consumption.
  • Human Impact on Ecosystems:
    • Deforestation, urbanization, industrialization
    • Agricultural intensification and land-use change
    • Resource extraction and waste generation
  • Urban Ecology: Ecosystem dynamics in urban areas — heat islands, green spaces, urban biodiversity.
  • **Social Ecology & Concepts:*
    • Kropotkin: Developed the idea of social interaction within social groups under the principle of Mutual aid.
    • Frederic le Play: Originator of the conceptual interplay between “place-work-folk”, a foundation of social geography.
    • Herbert Spencer: First applied Darwinism in the field of Social Ecology.
    • Deep Ecology: Characterized by a holistic view, green movements, and simple living (not anthropocentric).

Environmental Ethics and Deep Ecology

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UGC NET Human Interaction and Impacts, Environmental Ethics and Deep Ecology

Environmental ethics examines the moral relationship between humans and the natural environment, while deep ecology advocates for the inherent worth of all living beings regardless of their utility to humans.

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NoteEnvironmental Ethics
  • Anthropocentrism: Human-centred ethics — nature has value only insofar as it serves human needs.
  • Biocentrism: Life-centred ethics — all living organisms have inherent moral value (Paul Taylor).
  • Ecocentrism: Ecosystem-centred ethics — entire ecosystems, species, and ecological processes have intrinsic value (Aldo Leopold’s “Land Ethic”).
  • Tragedy of the Commons: A classic essay written by Garrett Hardin (1968), discussing the conflict between individual interests and the common good in resource management.
  • Intergenerational Equity: Obligation to preserve environmental quality for future generations.
  • Precautionary Principle: Where threats of serious damage exist, lack of scientific certainty should not postpone preventive measures.
TipDeep Ecology
  • Founded by Arne Naess (1973): A philosophical movement that goes beyond “shallow” environmentalism. Inspired by Gandhi and Spinoza, Naess reinforced his intuitions about the equal “right” of all species to flourish on the planet together with the Eastern doctrine of Ahimsa.
  • Core Principles:
    • All living beings have intrinsic value independent of human purposes
    • Richness and diversity of life are values in themselves
    • Humans have no right to reduce biological richness except for vital needs
    • Current human interference with nature is excessive
    • Fundamental changes in economic, technological, and ideological structures are necessary
  • Deep vs. Shallow Ecology:
    • Shallow Ecology: Reforms within existing framework (pollution control, resource management)
    • Deep Ecology: Radical re-evaluation of human relationship with nature
  • Related Movements: Social ecology (Murray Bookchin), Ecofeminism, Gandhian environmentalism, Chipko Movement.

Environmental Hazards & Disasters

Ozone Depletion

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UGC NET Unit III — Ozone depletion

Ozone depletion refers to the thinning of the Earth’s stratospheric ozone layer caused by human-made chemicals, exposing life on Earth to harmful ultraviolet radiation.

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NoteOzone Layer and Depletion
  • Ozone Layer: Located in the stratosphere (15–35 km altitude). Absorbs 97–99% of UV-B and UV-C radiation.
  • Ozone Formation: O₂ + UV → 2O; O + O₂ → O₃ (Chapman Cycle).
  • Ozone Depleting Substances (ODS):
    • Chlorofluorocarbons (CFCs) — refrigerants, aerosols
    • Halons — fire extinguishers
    • Carbon tetrachloride, methyl chloroform
    • Hydrochlorofluorocarbons (HCFCs)
  • Mechanism: CFCs release chlorine atoms in the stratosphere → catalytic destruction of ozone molecules. One chlorine atom can destroy ~100,000 ozone molecules.
  • Antarctic Ozone Hole: Discovered by Farman, Gardiner & Shanklin (1985). Polar stratospheric clouds (PSCs) accelerate ozone destruction in polar vortex conditions.
  • Effects of Ozone Depletion:
    • Increased UV-B radiation — skin cancer, cataracts, immune suppression
    • Damage to marine phytoplankton and aquatic ecosystems
    • Reduced crop yields and forest productivity
    • Degradation of plastics and materials
  • Montreal Protocol (1987): Global treaty to phase out ODS production — one of the most successful international environmental agreements.
  • Recovery: Ozone layer expected to recover to 1980 levels by ~2050–2070 if compliance continues.

Ozone Depletion — Detailed (NET Notes — Pulakesh Pradhan)

  • Troposphere Ozone → absorbs heat → **Bad Ozone*
  • Stratosphere Ozone → acts as UV-B filter → **Good Ozone*

Ozone Depleting Substances

  • CFC (Chlorofluorocarbons), Nitrogen Oxide (NOₓ), Hydrocarbons

Key Facts

  • Ozone hole found **above Antarctica*
  • 1% ozone lost → 2% more UV-B rays reach Earth
  • Chapman Mechanism: Cl + O₃ → ClO + O₂

Conferences on Ozone

Conference Year Outcome
Vienna Conference 1985 First conference to discuss ozone depletion
Montreal Protocol 1987 CFC reduction step by step
Helsinki Conference 1989 Strengthened Montreal Protocol
Saving the Ozone Layer Conference 1989 British Govt + UNEP; final withdrawal of all ozone-depleting gases

Global Warming and Climate Change

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UGC NET Environmental Hazards and Disasters: Global Warming

Global warming refers to the long-term increase in Earth’s average surface temperature primarily caused by enhanced greenhouse gas concentrations from human activities.

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NoteGlobal Warming Fundamentals
  • Greenhouse Effect: Natural process — CO₂, CH₄, N₂O, water vapour trap outgoing longwave radiation, warming Earth by ~33°C.
  • Enhanced Greenhouse Effect: Human activities (fossil fuel burning, deforestation, agriculture) increasing GHG concentrations beyond natural levels.
  • Key Greenhouse Gases: CO₂ (major contributor), Methane (CH₄), Nitrous Oxide (N₂O), CFCs, Ozone (tropospheric).
  • Evidence: Rising global temperatures (~1.1°C since pre-industrial era), shrinking ice sheets, rising sea levels, ocean acidification.
  • Impacts:
    • Sea-level rise — threat to coastal cities, island nations
    • Glacier retreat — Himalayan glaciers, Arctic sea ice
    • Extreme weather events — more frequent heatwaves, droughts, floods, cyclones
    • Ecosystem disruption — coral bleaching, habitat shifts, species migration
    • Agricultural impacts — changed growing seasons, water stress
  • IPCC (Intergovernmental Panel on Climate Change): Scientific body providing assessments on climate change — AR6 report.
  • Carbon Budget: Maximum CO₂ emissions to stay within 1.5°C or 2°C warming targets.
  • Mitigation Strategies: Renewable energy, carbon capture, afforestation, energy efficiency, circular economy.

Urban Heat Island

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UGC NET Environmental Hazards and Disasters: Urban Heat Island

The Urban Heat Island (UHI) effect is a phenomenon where urban areas experience significantly higher temperatures than surrounding rural areas due to human activities and built-environment characteristics.

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NoteUrban Heat Island Effect
  • Definition: Temperature difference between urban core and surrounding rural areas — can reach 2–8°C or more.
  • Causes:
    • Replacement of vegetation with impervious surfaces (concrete, asphalt)
    • Reduced evapotranspiration
    • Waste heat from vehicles, industries, air conditioning
    • Canyon effect — tall buildings trap heat and reduce wind flow
    • Dark surfaces absorbing more solar radiation (low albedo)
  • Types of UHI:
    • Surface UHI: Temperature differences in land surfaces (measured by remote sensing)
    • Atmospheric UHI: Air temperature differences (measured by weather stations)
    • Canopy Layer UHI: Within the urban canopy (ground to roof level)
    • Boundary Layer UHI: Above the urban canopy
  • Impacts:
    • Increased energy consumption (cooling demand)
    • Air quality degradation (ozone and smog formation)
    • Heat-related illness and mortality
    • Altered precipitation patterns (urban-induced convection)
    • Water quality impacts (thermal pollution of runoff)
  • Mitigation Strategies:
    • Green roofs and vertical gardens
    • Urban tree planting and green corridors
    • Cool roofs and cool pavements (high-albedo surfaces)
    • Urban planning and ventilation corridors
    • Urban modelling for city planning is effective in countering the UHI effect.
    • Water features and blue infrastructure

Environmental Policy & Governance

International Treaties, Programmes, and Agreements

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UGC NET International Treaties, International Programmes and Policies: Brundtland Commission, Kyoto Protocol, Agenda 21, Sustainable Development Goals, Paris Agreement

International environmental governance has evolved through landmark summits, treaties, and agreements aimed at addressing global environmental challenges through multilateral cooperation.

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NoteKey International Treaties and Programmes
  • Stockholm Conference (1972): First major international conference on environment — UNEP established. “Only One Earth” theme.
  • Brundtland Commission (1987): World Commission on Environment and Development — report “Our Common Future.” Defined sustainable development: “Meeting the needs of the present without compromising the ability of future generations to meet their own needs.”
  • Rio Earth Summit (1992): UNCED — produced Agenda 21, Rio Declaration, UNFCCC, CBD, Statement on Forest Principles. Principle of “Common but Differentiated Responsibilities.”
  • Agenda 21: Comprehensive plan of action for sustainable development in the 21st century — local, national, and global levels. Local Agenda 21 for community-level action.
  • Kyoto Protocol (1997): Legally binding emission reduction targets for developed (Annex I) countries. Clean Development Mechanism (CDM), Joint Implementation (JI), Emissions Trading. First commitment period: 2008–2012.
  • Johannesburg Summit (2002): World Summit on Sustainable Development — implementation of Agenda 21, partnerships for sustainable development.
  • Sustainable Development Goals (SDGs) — 2015: 17 goals with 169 targets adopted by UN General Assembly (Agenda 2030). Replace Millennium Development Goals (MDGs). Key goals include Climate Action (SDG 13), Life on Land (SDG 15), Life Below Water (SDG 14), Clean Water & Sanitation (SDG 6).
  • Paris Agreement (2015): Global framework to limit warming to well below 2°C (preferably 1.5°C). The 2-degree climate target has set the year 2100 to achieve it. Nationally Determined Contributions (NDCs). Global Stocktake every 5 years. India’s NDCs — 45% reduction in emissions intensity by 2030, 50% non-fossil fuel energy, net-zero by 2070.
  • UNFCCC: The basic objective of the UN Framework Convention on Climate Change is to stabilize greenhouse gas concentration in the atmosphere.
  • COP (Conference of Parties): Annual meetings under UNFCCC. Recent sequence: Bonn (2017), Katowice (2018), Madrid (2019), Glasgow (2021), Sharm el-Sheikh (2022), Dubai (2023).
  • Political Ecology: The relationship among power structure, the environment, and economic inequalities.

Environmental Policies & Treaties (NET Notes — Pulakesh Pradhan)

Year Conference / Protocol Key Outcome
1972 Stockholm Conference First global conference on human environment; UNEP established
1987 Montreal Protocol (16 Sept.) Protection of ozone layer; reduction of CFCs; initially signed by 46, now 200 countries
1992 Rio Earth Summit (UNCED) Agenda 21; Convention on Biological Diversity
1997 Kyoto Protocol Reduction of greenhouse gas emissions; 141 countries signed
2002 Johannesburg Summit (WSSD) World Summit on Sustainable Development
2015 Paris Agreement Limit global warming to 1.5–2°C above pre-industrial levels

Books and Further Readings

Environmental Geography provides the essential bridge between physical processes and human impacts. Explore Climatology and Oceanography for deeper physical science perspectives.

Quick Reference

Environmental Geography Quick Reference

Key Books and Authors

Book Author Year
Silent Spring Rachel Carson 1962
The Limits to Growth Donella Meadows et al. (Club of Rome) 1972
Our Common Future (Brundtland Report) WCED 1987
Ecology and Environment P.D. Sharma -
Fundamentals of Ecology E.P. Odum 1953
Sand County Almanac Aldo Leopold 1949
Population Bomb Paul R. Ehrlich 1968

Key Concepts & Propounders

Concept Propounder Description
Ecology (Term) Ernst Haeckel Study of interactions between organisms and environment
Ecosystem Concept A.G. Tansley (1935) Biological community of interacting organisms and their physical environment
Deep Ecology Arne Naess (1973) Intrinsic value of all living beings regardless of human utility
Biodiversity Hotspots Norman Myers (1988) Areas with high endemism and high habitat loss
Biosphere Reserve UNESCO (MAB - 1971) Protected areas representing major ecosystems
Ecological Niche Joseph Grinnell / Charles Elton Role and position a species has in its environment
Tragedy of the Commons Garrett Hardin (1968) Overexploitation of shared resources
Gaia Hypothesis James Lovelock Earth as a self-regulating, living organism

Global Environmental Initiatives

Initiative / Protocol Year Objective
Stockholm Conference 1972 First global conference on environment (UNEP created)
Montreal Protocol 1987 Protection of the Ozone Layer (Phasing out CFCs)
Earth Summit (Rio) 1992 Agenda 21, UNFCCC, CBD, UNCCD
Kyoto Protocol 1997 Legally binding emission reduction targets
Paris Agreement 2015 Limit global warming to well below 2°C

Notes compiled by Geography Team