1. Biodiversity Conservation

In-situ Conservation

In-situ Conservation refers to the active and scientific protection of species within their natural habitats. Under this approach, organisms continue to live, breed, interact, and evolve in the same ecological conditions where they naturally occur. Since conservation takes place within the original ecosystem, not only the target species but also the associated flora, fauna, and ecological processes receive protection. Thus, in-situ conservation helps maintain overall ecosystem integrity and biodiversity.In contrast, Ex-situ Conservation involves conserving species outside their natural habitats through facilities such as zoological parks, botanical gardens, seed banks, captive breeding centres, and wildlife safari parks.

Biodiversity Hotspots in India

India contains four globally recognized biodiversity hotspots.

The Indo-Burma Hotspot extends across northeastern India and neighboring Southeast Asian countries and supports a highly diverse assemblage of endemic flora and fauna.

Species Diversity

Approximately 1.75 million species have been scientifically identified and documented worldwide. A large proportion of these belong to insects.India accounts for nearly 7–8% of globally documented species, including:

Several million species remain undiscovered, particularly in rainforests, deep oceans, and soil ecosystems.

2. Evolution of Earth

Hadean Eon (4.6–4.0 Billion Years Ago)

The Hadean Eon represents the earliest stage of Earth's history. During this period, Earth was characterized by extreme temperatures, widespread volcanic activity, and frequent asteroid impacts. Environmental conditions were highly hostile, making the planet unsuitable for life.

Geological Time Scale

3. Ecological Succession

Reaction Stage

The Reaction Stage is the phase during ecological succession in which existing organisms actively modify their environment, creating conditions favorable for subsequent species.A classic example is the action of lichens, which break down rocks into soil. The newly formed soil subsequently allows mosses and other plant species to establish.

Stages of Succession

4. Adaptation

Adaptation is the process through which organisms become better suited to survive and reproduce in their environment.

Morphological Adaptation

These are physical structural modifications.Examples:

• Arctic Fox: White winter fur and darker summer coat.
• Camel: Hump for fat storage and long eyelashes.
• Cactus: Spines reduce water loss and deter herbivores.

Physiological Adaptation

These involve internal biological processes.Examples:

• Venom production in snakes.
• Water retention in desert toads.
• Increased red blood cell production at high altitudes.

Behavioral Adaptation

These involve changes in behavior.Examples:

• Migration of Monarch butterflies.
• Cooperative hunting in dolphins.
• Sentinel behavior in meerkats.

Adaptive Radiation

Adaptive Radiation refers to the diversification of a single ancestral species into multiple species adapted to different ecological niches.A classic example is the Hawaiian Honeycreepers, which evolved diverse beak forms for exploiting different food resources.

5. Ecological Concepts

Habitat Niche

A Habitat Niche describes the physical place where an organism lives.Other niche dimensions include:

Ecotone

An Ecotone is a transition zone between two ecosystems.Characteristics:

• Zone of tension.
• High species diversity.
• Presence of edge species.
• Strong Edge Effect.

Examples:

• Mangroves.
• Estuaries.
• Marshlands.
• Grasslands between forests and deserts.

Ecocline

An Ecocline is a gradual change in ecosystem characteristics along an environmental gradient.Examples:

• Altitudinal vegetation changes on mountains.
• Salinity gradients between rivers and seas.

Mountain Ecocline

6. Ecosystem Productivity

Gross Primary Productivity (GPP)

GPP represents the total energy fixed by producers through photosynthesis.

Net Primary Productivity (NPP)

NPP is the energy remaining after producers meet their respiratory requirements.

Formula

NPP = GPP − RespirationNPP represents the actual energy available to consumers.

Lindeman's 10% Law

Proposed by Raymond Lindeman (1942).Only 10% of energy is transferred from one trophic level to the next.The remaining 90% is lost through:

• Respiration
• Heat
• Metabolic activities
• Waste

7. Biogeochemical Cycles

Sulphur Cycle

Sulphur is an essential component of:

• Proteins
• Enzymes
• Vitamins

Plants absorb sulphur primarily as sulphate ions.Major reservoirs include:

• Oceans
• Rocks
• Atmosphere

Natural Sources

• Weathering of rocks
• Volcanic eruptions
• Hydrothermal vents

Human Impact

Burning fossil fuels releases Sulphur Dioxide (SO₂), leading to the formation of acid rain.

Nitrogen Cycle

Nitrogen Fixation

Conversion of atmospheric nitrogen into usable forms such as:

• Ammonia (NH₃)
• Nitrates (NO₃⁻)

Major nitrogen-fixing bacteria:

• Rhizobium

Other Processes

8. Carbon Cycle

Oceans as Carbon Sinks

Oceans absorb approximately 25% of annual global carbon dioxide emissions, making them major carbon sinks.Carbon is stored:

• In surface waters
• In deep ocean layers

Ocean Outgassing

The release of dissolved carbon dioxide from oceans back into the atmosphere is called Outgassing.

Forests as Carbon Sinks

Forests absorb carbon dioxide through photosynthesis and store carbon in:

• Biomass
• Soil
• Roots
• Leaves

They play a critical role in climate change mitigation.

Carbon Sequestration

Types

Iron Fertilization

A form of ocean sequestration involving the addition of iron to stimulate phytoplankton growth, thereby increasing carbon dioxide uptake.

9. Air Pollution

Air pollutants are classified into:

Indoor Pollutants

Generated through:

• Cooking
• Smoking
• Air conditioning systems

Common pollutants:

• Carbon Monoxide (CO)
• Carbon Dioxide (CO₂)
• Volatile Organic Compounds (VOCs)

Outdoor Pollutants

Generated through:

• Transportation
• Industries
• Power plants

Common pollutants:

• PM₂.₅
• PM₁₀
• Nitrogen Oxides (NOx)

Particulate Matter (PM)

Fine particulate matter penetrates deep into lungs and bloodstream.Health impacts include:

• Cardiovascular diseases
• Respiratory disorders
• Stroke

Air Pollution Mortality

Air pollution contributes to more than 1.2 million deaths annually in India, causing severe respiratory, cardiovascular, and neurological diseases.

10. Ozone Layer

Formation of Ozone

Ozone formation begins when UV-C radiation splits oxygen molecules (O₂) into free oxygen atoms.Reaction:O₂ + UV-C → O + OO + O₂ → O₃This process occurs in the stratosphere (15–30 km altitude).

Ozone Destruction

Natural ozone destruction occurs through catalytic reactions involving:

• Nitrogen
• Chlorine
• Hydrogen
• Bromine

Ozone Layer Protection

The ozone layer absorbs harmful ultraviolet radiation between 100–315 nm, protecting life on Earth.

Montreal Protocol

Member countries are required to submit annual ODS data reports for monitoring the phase-out of ozone-depleting substances.

Vienna Convention

Entered into Force

1988

Objective

Protection of human health and the environment from ozone layer depletion.

Features

• International framework convention.
• Encourages research and monitoring.
• No legally binding phase-out targets.

Ozone Depletion Discovery

In 1974, Sherwood Rowland and Mario Molina warned about the harmful effects of CFCs on the ozone layer.They, along with Paul Crutzen, received the 1995 Nobel Prize in Chemistry.

11. Climate Change

Global Warming Potential (GWP)

Carbon dioxide is the reference gas and is assigned a GWP value of 1.

Nitrous Oxide (N₂O)

• Contributes around 6% of global greenhouse gas emissions.
• GWP approximately 298 times greater than CO₂.
• Also contributes to ozone layer depletion.

Fluorinated Gases (F-Gases)

Characteristics:

• Entirely synthetic.
• Extremely long atmospheric lifetimes.
• Very high GWP.

Major categories:

• HFCs
• PFCs
• SF₆

Adaptation vs Mitigation Funds

Mission LiFE

Launched at COP-26 Glasgow (2021).Objective:Promote sustainable lifestyles and encourage individuals to become Pro-Planet People (P3).

Three-Phase Strategy

1. Change in Demand
2. Change in Supply
3. Change in Policy

12. Water Pollution

Biological Pollutants

Major source:

• Untreated sewage
• Domestic waste

Diseases:

• Cholera
• Typhoid
• Gastrointestinal diseases

Water-Soluble Inorganic Pollutants

Include:

• Acids
• Salts
• Mercury
• Lead

Effects:

• Reduced water quality
• Toxicity
• Ecosystem degradation

Eutrophication

Occurs due to excessive nutrient enrichment.Characteristics:

• High turbidity
• Algal blooms
• Low dissolved oxygen
• Reduced biodiversity

Dead Zones

Hypoxic regions where aquatic life cannot survive.

Major Dead Zones

13. Wetlands

Ramsar Sites in India

As of June 2026, India has 100 Ramsar Sites.The 100th Ramsar Site:Jai Prakash Narayan Bird Sanctuary (Surha Tal), Uttar PradeshIndia became a Contracting Party to the Ramsar Convention on 1 February 1982.

14. Waste Management

Gasification

A thermal waste treatment process that converts carbon-based waste into Syngas without direct combustion.Advantages:

• Clean energy generation.
• Reduced landfill burden.
• Minimal waste residue.

Limitation:

• High initial cost.

Biomedical Waste

Sharps include:

• Needles
• Syringes
• Scalpels
• Broken glass

Star Rating of Garbage-Free Cities

Evaluates urban sanitation through a five-star rating system based on:

• Waste collection efficiency
• Waste processing capacity
• Innovative waste management practices

15. Namami Gange Programme

Launched in 2014 for the rejuvenation of the Ganga River.The programme received recognition as one of the Top 10 UN World Restoration Flagships.

Phase-II (2021–2026)

Focus Areas:

• Restoration of small rivers.
• Wetland restoration.
• Reuse of treated water.

Institutional Structure

Clean Ganga Fund

Established in 2015 to facilitate public participation in river conservation.