Environment and Ecology — Ecosystems, Biodiversity, Pollution, Climate Change for PSC

Environment and Ecology questions appear in every PSC exam (2-5 questions). Focus on biodiversity hotspots, environmental laws, international protocols, and pollution-related facts.

Ecosystem Basics

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

Components

Component	Type	Examples
Abiotic	Non-living	Sunlight, water, temperature, soil, minerals
Biotic	Living	Producers, consumers, decomposers

Trophic Levels

Level	Role	Examples
1st	Producers (Autotrophs)	Plants, algae, cyanobacteria
2nd	Primary consumers (Herbivores)	Deer, rabbit, grasshopper
3rd	Secondary consumers (Carnivores)	Frog, small fish
4th	Tertiary consumers (Top carnivores)	Tiger, eagle, shark
All levels	Decomposers	Bacteria, fungi

10% Rule (Lindeman’s Law): Only ~10% of energy transfers from one trophic level to the next.

Types of Ecosystems

Type	Examples
Terrestrial	Forest, grassland, desert, tundra
Aquatic — Freshwater	Rivers, lakes, ponds, wetlands
Aquatic — Marine	Oceans, coral reefs, estuaries
Artificial	Croplands, aquariums, gardens

Biodiversity

Biodiversity = variety of life at genetic, species, and ecosystem levels.

Biodiversity Hotspots

A hotspot must have: (1) at least 1,500 endemic vascular plants, and (2) lost at least 70% of original habitat.

World Hotspots (36 total)	Notable ones
India’s hotspots	(1) Western Ghats and Sri Lanka, (2) Eastern Himalayas, (3) Indo-Burma, (4) Sundaland (partially)
Richest hotspot globally	Tropical Andes
Most species-rich in India	Western Ghats

Types of Species

Type	Definition
Endemic	Found exclusively in a specific region (e.g., Lion-tailed macaque in Western Ghats)
Exotic/Alien	Introduced from outside (e.g., Lantana, water hyacinth)
Keystone	Disproportionate effect on ecosystem relative to abundance (e.g., fig trees)
Indicator	Indicates environmental health (e.g., lichens indicate air quality)

IUCN Red List Categories

Mnemonic: “LC-NT-VU-EN-CR-EW-EX” (Least to most threatened)

Category	Abbreviation
Least Concern	LC
Near Threatened	NT
Vulnerable	VU
Endangered	EN
Critically Endangered	CR
Extinct in the Wild	EW
Extinct	EX

Pollution

Air Pollution

Pollutant	Source	Effect
CO (Carbon Monoxide)	Vehicle exhaust, incomplete combustion	Binds with haemoglobin, reduces oxygen transport
SO2 (Sulphur Dioxide)	Burning fossil fuels, industries	Acid rain, respiratory problems
NO2 (Nitrogen Dioxide)	Vehicle exhaust, power plants	Smog, acid rain
PM 2.5	Construction, vehicles, burning	Penetrates lungs, causes cardiovascular disease
CFCs	Refrigerants, aerosols	Ozone layer depletion

Water Pollution

Term	Meaning
BOD (Biological Oxygen Demand)	Higher BOD = more polluted water
Eutrophication	Excessive nutrients cause algal bloom, oxygen depletion
Biomagnification	Toxin concentration increases up the food chain (e.g., DDT)
Bioaccumulation	Toxin builds up in a single organism over time

Ozone Layer

• Ozone layer is in the stratosphere (15-35 km altitude).
• Ozone hole was discovered over Antarctica (1985, by Farman, Gardiner, Shanklin).
• Montreal Protocol (1987): International treaty to phase out CFCs and other ozone-depleting substances. Most successful environmental treaty.
• Dobson Unit (DU): Measures ozone column thickness.

Climate Change

Concept	Detail
Greenhouse gases	CO2, CH4 (methane), N2O, CFCs, water vapour
Most abundant GHG	Water vapour (but CO2 is the primary driver of climate change)
Highest warming potential	SF6 (sulphur hexafluoride) — 23,500 times more than CO2
Global warming	Rise in average earth temperature due to increased GHGs
Carbon footprint	Total GHG emissions by a person/organisation

Key International Agreements

Agreement	Year	Key Points
UNFCCC	1992	Framework Convention at Rio Earth Summit
Kyoto Protocol	1997	Binding emission reduction targets for developed countries; CDM mechanism
Paris Agreement	2015	Limit warming to 1.5-2 degrees C; India’s target: 45% reduction in emission intensity by 2030
COP (Conference of Parties)	Annual	Decision-making body of UNFCCC
Montreal Protocol	1987	Ozone-depleting substances (NOT a climate treaty, but has climate benefits)
Stockholm Conference	1972	First global environment conference; led to UNEP

Environmental Laws in India

Law	Year	Purpose
Wildlife Protection Act	1972	Protection of wild animals and plants; established National Parks, Sanctuaries
Water (Prevention and Control of Pollution) Act	1974	Established Central/State Pollution Control Boards
Forest Conservation Act	1980	Restricts diversion of forest land for non-forest purposes
Air (Prevention and Control of Pollution) Act	1981	Air quality standards, pollution control
Environment Protection Act	1986	Umbrella legislation; empowers central government (post-Bhopal disaster)
Biodiversity Act	2002	National Biodiversity Authority (Chennai); regulates access to biological resources
National Green Tribunal (NGT)	2010	Specialised tribunal for environmental cases; established under NGT Act
EIA Notification	1994 (revised 2006)	Environmental Impact Assessment mandatory for projects

Important Environmental Bodies

Body	Role
CPCB	Central Pollution Control Board (under MoEFCC)
NBA	National Biodiversity Authority (Chennai)
NBWL	National Board for Wildlife (chaired by PM)
Animal Welfare Board	Under AWBI Act; HQ in Chennai
Wildlife Institute of India	Dehradun
Indian Institute of Forest Management	Bhopal

Protected Areas in India

Type	Number (approx.)	Established Under
National Parks	106	Wildlife Protection Act, 1972
Wildlife Sanctuaries	567	Wildlife Protection Act, 1972
Biosphere Reserves	18	UNESCO MAB Programme
Tiger Reserves	56	Project Tiger (1973)

First National Park in India: Jim Corbett National Park (1936, Uttarakhand) — originally Hailey National Park.

First Biosphere Reserve in India: Nilgiri Biosphere Reserve (1986).

Kerala Protected Areas: Periyar Tiger Reserve, Silent Valley National Park (saved from hydroelectric project in 1980s), Eravikulam National Park (Nilgiri Tahr), Parambikulam Tiger Reserve.

Quick Revision Mnemonics

Greenhouse gases order by warming potential: “SF6 > CFCs > N2O > CH4 > CO2” — “Super Ferocious Cats Never Chase Crows.”

India’s biodiversity hotspots: “WISE” — Western Ghats, Indo-Burma, Sundaland, Eastern Himalayas.

Environmental Acts chronology: “WaFAEB” — Water (1974), Forest (1980), Air (1981), Environment (1986), Biodiversity (2002).