NotesCaféEnvironment and EcologyContents
UPPCS Mains
2026 Edition
General Studies Paper III
Smart Notes

Environment and Ecology

English Medium
4
Chapters
22
Topics
66
Figures & Maps
21
Tables
What's Inside
  1. 01Ecosystems, Biodiversity and Coastal Ecosystems
  2. 02Biodiversity Conservation: Protected Areas, Laws and People
  3. 03Environmental Pollution and Waste Management
  4. 04Climate Change and Environmental Impact Assessment
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Environment and Ecology
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Environment and Ecology
UPPCS Mains · Smart Notes

Contents

Environment and Ecology · General Studies Paper III
  1. 01Ecosystems, Biodiversity and Coastal Ecosystems5 topics
    1. 1.1Ecosystems: Functions, Services and Environmental Security
    2. 1.2Biodiversity: Meaning, Levels, Distribution and Significance
    3. 1.3Wetlands and the Ramsar Convention
    4. 1.4Mangroves and Coral Reefs
    5. 1.5Coastal Zone Management: Blue Economy, Coastal Erosion and CRZ
  2. 02Biodiversity Conservation: Protected Areas, Laws and People5 topics
    1. 2.1Biodiversity Loss and Conservation Strategies: HIPPO, In-situ and Ex-situ, GBF and Nature-Based Solutions
    2. 2.2Protected Areas, Biodiversity Hotspots and Ecologically Sensitive Areas
    3. 2.3Wildlife Conservation: WPA 1972, NWAP 2017–31, Species Projects and Challenges
    4. 2.4Biodiversity and Forest Laws: Biological Diversity Act, Forest Conservation Act, Forest Rights Act and National Forest Policy
    5. 2.5People and Conservation: Citizen Movements and Sacred Groves
  3. 03Environmental Pollution and Waste Management7 topics
    1. 3.1Air Pollution: Smog, Sources, NCAP and Air-Quality Governance
    2. 3.2Water Pollution and the Namami Gange Programme
    3. 3.3Environmental Degradation: Land, Soil and Forests
    4. 3.4Noise, Light and Radiation Pollution
    5. 3.5Solid and Biomedical Waste Management
    6. 3.6E-Waste and Space Pollution: Sources, Rules and Management
    7. 3.7Plastic Waste and Microplastics
  4. 04Climate Change and Environmental Impact Assessment5 topics
    1. 4.1Climate Change: Science, Greenhouse Effect and Causes
    2. 4.2Impacts of Climate Change on India, Vulnerability and Adaptation
    3. 4.3Development–Emission Balance and India's Climate Response: NDCs, Mitigation and Climate Finance
    4. 4.4Environmental Impact Assessment: Legal Basis, Process and Evolution in India
    5. 4.5EIA in Practice: Critique, Post-Facto Clearances and Reform
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Environment and EcologyChapter 01 · Topic 1
Chapter 01

Ecosystems, Biodiversity and Coastal Ecosystems

Environment and Ecology · 5 topics
Topic 1

Ecosystems: Functions, Services and Environmental Security

Chapter Overview

This chapter lays the base of environmental studies: how ecosystems work and serve people, the biodiversity they hold, and three systems at the land–water edge: wetlands, mangroves and coral reefs, and the coastal zone. In 2022 the Kunming–Montreal Global Biodiversity Framework set the goal of conserving 30% of land and sea and restoring 30% of degraded ecosystems by 2030, and India's updated NBSAP (2024) follows it.

Topic 1 explains ecosystem structure, functions, services and environmental security. Topic 2 defines biodiversity, its levels and why the tropics and India are so rich in it. Topics 3 and 4 take up wetlands, mangroves and coral reefs, and Topic 5 turns to managing the coast: the blue economy, coastal erosion and the CRZ rules. Threats to biodiversity and conservation strategies follow in Chapter 2.

Topic Flow
  1. 1Ecosystems: functions, services and security
  2. hold the variety of life called
  3. 2Biodiversity: meaning, levels and distribution
  4. thrives in places such as
  5. 3Wetlands and the Ramsar Convention
  6. meet the sea in
  7. 4Mangroves and coral reefs
  8. shield a coast that needs
  9. 5Coastal zone management

The Kunming–Montreal Global Biodiversity Framework (2022) asks every country to restore at least 30% of its degraded ecosystems by 2030 (CBD). An ecosystem is a functional unit in which living organisms (biotic components) interact with their non-living surroundings (abiotic components) through energy flow and nutrient cycling.

Structure and Functions of an Ecosystem

  1. Components: producers, consumers and decomposers form the biotic part, while sunlight, water, soil and nutrients form the abiotic part of every ecosystem; e.g. a village pond: algae, fish, bacteria, water and silt; an ecotone is the transition zone between two ecosystems, such as a mangrove belt, where the edge effect brings more species.
  2. Energy flow and nutrient cycling: energy flows one way through trophic levels and, by the 10% law, only about 10% passes to the next (Lindeman, 1942); decomposers recycle nutrients; e.g. grass → deer → tiger; fertiliser runoff overloads the phosphorus cycle and causes eutrophication of lakes.
  3. Food webs and ecological pyramids: interlinked food chains give stability; the pyramid of energy is always upright, while pyramids of number or biomass can be inverted; e.g. inverted pyramid of numbers on a single tree carrying many insects; a keystone species, such as the elephant or the fig tree, shapes its web far beyond its numbers.
  4. Ecological succession: communities change in sequence from pioneer species through seral stages to a stable climax community; primary on bare ground, secondary on disturbed soil; e.g. primary on bare rock or cooled lava; secondary on abandoned farmland or after a forest fire; the same sequence guides restoration of degraded habitats.
  5. Productivity: gross primary productivity (GPP) is the rate producers fix solar energy; net primary productivity (NPP), GPP minus respiration, is left for consumers; e.g. tropical rainforests and estuaries rank among the most productive ecosystems.
Main types of ecosystems with Indian examples
Fig. 1.1 Main types of ecosystems with Indian examples
One-way energy flow through trophic levels (10% law)
Fig. 1.2 One-way energy flow through trophic levels (10% law)

Ecosystem Services, Carrying Capacity and Environmental Security

  1. Ecosystem services: the benefits people draw from ecosystems, grouped by the Millennium Ecosystem Assessment (2005) into provisioning, regulating, cultural and supporting services; e.g. forests store carbon, wetlands hold back floods, bees pollinate crops.
  2. Carbon sink: India's forests and land use removed 571.82 Mt CO2e in 2022, a regulating service set against emissions of 3,396.37 Mt CO2e excluding land use; e.g. inventory year 2022, in India's first Biennial Transparency Report (BTR-1) to the UNFCCC (2024).
  3. Carrying capacity: the largest population an area can support indefinitely with its resources and waste-absorbing capacity; it guides the planning of towns, tourism and fisheries; e.g. maximum sustainable yield (MSY) in fisheries; visitor caps in fragile hill towns; overshoot brings water scarcity, land degradation and heavier pollution.
  4. Environmental security: protection of ecosystems and natural resources as the base of water, food, health and national security (disasters: see GS-3 Disaster Management); e.g. Himalayan glaciers retreat about 14.9 m a year, a risk to Indus, Ganga and Brahmaputra flows (MoES, 2025).
Table 1.1 The Millennium Ecosystem Assessment (UN, 2005) gave these four classes; supporting services underpin the other three.
Service (MEA, 2005)What it providesIndian example
Provisioningfood, fresh water, timber, fuel, medicinal plants, genetic resourcesminor forest produce such as tendu leaves and mahua
Regulatingclimate and flood regulation, water purification, pollination, disease controlEast Kolkata Wetlands treat city wastewater
Culturalspiritual, recreational, aesthetic and educational valuesacred groves; wildlife tourism in tiger reserves
Supportingsoil formation, nutrient cycling and primary production that keep the other services goingnutrient-rich Sundarbans mudflats feeding fish nurseries

Main Threats to Ecosystems

  1. Habitat loss and fragmentation: clearing and splitting of forests, grasslands and wetlands for farms, mines, roads and towns is the main driver of decline (see Ch 2, Topic 1); e.g. diverting forest land needs Central approval under the Van (Sanrakshan Evam Samvardhan) Adhiniyam, 1980, on advice from the Forest Advisory Committee.
  2. Invasive species, pollution, overuse and climate change: alien species outcompete natives, pollutants upset nutrient cycles, overharvesting drains stocks, and warming shifts species ranges faster than ecosystems adjust; e.g. water hyacinth in Indian lakes; Lantana and Parthenium on native plants; Nile perch in Lake Victoria.
The five main threats to ecosystems
Fig. 1.3 The five main threats to ecosystems

Gaps in Implementation

India has strong forest, wildlife and environment laws, but the economic value of ecosystem services still rarely shapes budgets, project approvals or town planning.

  1. Value left out of decisions: MoSPI values forest services under the UN System of Environmental-Economic Accounting (SEEA), yet these accounts seldom enter budgets or project appraisal; e.g. regulating services such as carbon retention were valued at about 2.63% of GDP in 2021-22 (MoSPI, 2025).
  2. Scattered monitoring: forests, species and pollution are tracked by separate bodies, so no single measure shows the health of an ecosystem as a whole; e.g. FSI for forest cover, BSI and ZSI for species (all under MoEFCC), CPCB (s 3, Water Act, 1974) for pollution.
  3. Carrying capacity ignored: roads, hotels and housing in fragile hills and coasts often go ahead without carrying-capacity studies, raising disaster and degradation risks; e.g. Joshimath land subsidence (2023) revived calls for such studies of Himalayan towns.

Ecosystems: Way Forward

  1. Ecosystem-based approach: restore degraded land under the GBF target and count lost ecosystem services as a cost in budgets and impact assessment; e.g. Green India Mission (2014): tree cover on 5 million ha and better forest quality on another 5 million ha.
  2. People and lifestyles: Mission LiFE (2022) seeks low-consumption lifestyles, and local care of forests, wetlands and coasts speeds their recovery (see Ch 4, Topic 3); e.g. over 6 crore people joined 34 lakh LiFE events by 2025 (PIB, 2025).

Counting ecosystem services in natural capital accounts and achieving the GBF restoration target will make healthy ecosystems the base of India's environmental security and of SDG 15.

Based on NCERT, Standard Books references, Keywords from Syllabus and Previous Year question Papers

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Environment and EcologyChapter 01 · Topic 2
Topic 2

Biodiversity: Meaning, Levels, Distribution and Significance

Ecosystems carry the variety of life, and in October 2024 India launched its updated National Biodiversity Strategy and Action Plan (2024–2030) with 23 national targets at CBD COP16 (PIB, 2024). Under Article 2 of the Convention on Biological Diversity (1992), biodiversity is the variability among living organisms from all sources, including diversity within species, between species and of ecosystems.

Levels and Measures of Biodiversity

  1. Genetic diversity: variation in genes within a species, the base for adaptation, crop breeding and resistance to pests and disease; e.g. Basmati, IR-8 and red rice are genetically different varieties of one species.
  2. Species diversity: the number of species in an area (richness) and how evenly individuals are spread among them (evenness); e.g. Western Ghats endemics such as the lion-tailed macaque and the purple frog.
  3. Ecosystem diversity: the variety of habitats, communities and ecological processes in a region, from deserts and forests to reefs; e.g. Ladakh cold desert, Sundarbans mangroves and Lakshadweep coral reefs.
  4. Alpha, beta and gamma diversity: alpha counts species within one community, beta measures species turnover between communities, and gamma is the total for a whole region (Whittaker); e.g. beta diversity rises from the Shivalik foothills to the alpine meadows of the Himalaya.
The three levels of biodiversity and how diversity is measured
Fig. 1.4 The three levels of biodiversity and how diversity is measured

Distribution: The Latitudinal Gradient and Megadiverse India

  1. Latitudinal gradient: species richness generally falls from the equator towards the poles, so tropical countries hold far more species than temperate ones; e.g. birds: Colombia about 1,400 species, New York 105, Greenland 56 (NCERT).
  2. More solar energy: the tropics receive more solar energy through the year, which raises productivity and indirectly supports more species; e.g. tropical rainforests have very high net primary productivity.
  3. Stable, predictable climate: tropical environments are less seasonal and more constant, which allows niche specialisation and so a greater number of species; e.g. year-round fruiting supports specialist fruit-eaters such as hornbills.
  4. Long evolutionary time: temperate regions were repeatedly glaciated, while the tropics stayed undisturbed for millions of years, giving more time for species to diversify; e.g. the tropical belt is also the largest land area, and richness rises with area (species–area relation, Humboldt).
  5. Megadiverse India: India holds about 8% of recorded species on 2.4% of the world's land: over 96,000 animal and about 47,000 plant species (PIB, 2026); e.g. one of the megadiverse countries, with high endemism in the Western Ghats and the North-East.
  6. Biodiversity hotspots: India has four of the 36 global hotspots, which by definition have lost at least 70% of native vegetation (criteria: see Ch 2, Topic 2); e.g. Western Ghats forest lost to tea, coffee and infrastructure (CEPF, 2026); map sites: Valley of Flowers (Himalaya), Keibul Lamjao (Indo-Burma), Silent Valley (Western Ghats and Sri Lanka), Great Nicobar (Sundaland).
  7. Biogeographic zones: India is divided into ten biogeographic zones, each with its own climate, landforms and signature species (Wildlife Institute of India); e.g. Thar: Great Indian Bustard; North-East: hoolock gibbon; islands: Nicobar megapode.
Table 1.2 Ten zones as classified by the Wildlife Institute of India (Rodgers and Panwar); biomes and natural vegetation: see GS-1 Geography.
Biogeographic zoneSignature species or feature
Trans-Himalayasnow leopard; cold desert of Ladakh
Himalayared panda, Himalayan brown bear
DesertGreat Indian Bustard, desert fox, khejri tree
Semi-aridAsiatic lion (Gir), blackbuck
Western Ghatslion-tailed macaque, purple frog
Deccan Peninsulatiger, sloth bear and gaur of central Indian forests
Gangetic Plainswamp deer, Gangetic dolphin (UP: Dudhwa, see GS-6)
North-Easthoolock gibbon, golden langur, Amur falcon passage
Coastsmangroves, olive ridley nesting beaches
IslandsNicobar megapode, dugong, coral reefs
Bird species fall from the equator towards the poles (latitudinal gradient)
Fig. 1.5 Bird species fall from the equator towards the poles (latitudinal gradient)
India's four biodiversity hotspots: one marker each, with example sites
Fig. 1.6 India's four biodiversity hotspots: one marker each, with example sites

Significance of Biodiversity

  1. Ecosystem stability: more diverse ecosystems resist and recover from shocks better; losing species weakens them like rivets popped from an aircraft (Ehrlich); e.g. mangroves buffer storm surges on the east coast (see Topic 4).
  2. Food security: crop wild relatives and traditional varieties supply genes for yield, drought tolerance and pest resistance as the climate changes; e.g. wild relatives of rice and wheat; millets and landraces of rainfed farms.
  3. Medicine: many drugs come from plants and microbes, and traditional systems such as Ayurveda depend on wild medicinal plants; e.g. vincristine from periwinkle for cancer; quinine from cinchona for malaria; bioprospecting, the search for useful compounds in nature, finds such leads (see Ch 2, Topic 4).
  4. Disease regulation: intact ecosystems keep pathogens in check, while habitat loss brings people, livestock and wildlife closer and raises zoonotic spillover (One Health); e.g. bat-borne Nipah virus outbreaks in Kerala since 2018.
  5. Economic and cultural value: bioresources support tourism, medicine and livelihoods, and access and benefit sharing (ABS) returns part of the gain to communities; e.g. ABS approvals released nearly ₹145 crore to about 11,000 Biodiversity Management Committees (PIB, 2026; see Ch 2, Topic 4).
  6. Climate regulation: forests, wetlands and mangroves hold carbon and moderate local climate, so conserving biodiversity also helps India's climate mitigation and adaptation; e.g. India's NDC 2031–35 (2026) targets a forest and tree carbon sink of 3.5–4.0 billion tonnes CO2e (see Ch 4, Topic 3).
Why biodiversity matters
Fig. 1.7 Why biodiversity matters

Gaps in Implementation

India's laws and its 23-target NBSAP are in place, yet knowledge, money and the safeguarding of genetic resources lag behind the scale of its biological wealth (threat detail: see Ch 2, Topic 1).

  1. Knowledge gaps: insects, fungi, microbes and deep-sea life remain poorly surveyed, so many species may vanish before they are even described; e.g. survey bodies BSI and ZSI under MoEFCC still record new species every year.
  2. Funding gap: the global framework needs USD 200 billion a year by 2030, and developing countries depend heavily on external finance to meet it; e.g. Kunming–Montreal GBF resource target (CBD, 2022); India's own spending: see Ch 2, Topic 1.
  3. Genetic erosion: high-yield varieties and hybrids replace local landraces and crop wild relatives, so the gene pool for future breeding and climate adaptation keeps narrowing; e.g. IR-8 (1966) and later high-yield rices spread in the Green Revolution while many local rice landraces shrank.

Biodiversity: Way Forward

  1. 30 by 30: conserve at least 30% of land, inland waters, coastal and marine areas by 2030 under GBF Target 3, with which India's NBSAP is aligned; e.g. NBSAP 2024–2030 with 23 national targets (PIB, 2024).
  2. Custodians of genetic wealth: keep landraces and crop wild relatives alive on farms and in seed banks and reward their custodians (benefit sharing: see Ch 2, Topic 4); e.g. ICAR-NBPGR, New Delhi, runs the National Gene Bank; the Protection of Plant Varieties and Farmers' Rights Act, 2001 protects farmers' varieties.
  3. Science-based monitoring: use DNA methods, remote sensing and citizen science to track species and habitats and to set conservation priorities; e.g. DNA-based elephant estimation 2021–25 counted 22,446 wild elephants (WII, 2025).

Achieving the NBSAP (2024–2030) targets under the Kunming–Montreal GBF will decide whether India's megadiversity survives rapid development.

Based on NCERT, Standard Books references, Keywords from Syllabus and Previous Year question Papers

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