Biogeography and Ecology

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Biogeography and Ecology — Key Facts for BPSC Examination

Biogeographical Realm:

Realm	Distribution
Palearctic	Europe, N Asia, N Africa
Nearctic	North America (N of Mexico)
Neotropical	South America, Central America
Ethiopian	Africa (S of Sahara), Arabia
Oriental	S Asia, SE Asia
Australian	Australia, NZ, Pacific islands

Wallace Line: Boundary between Oriental and Australian realms (passes between Bali and Lombok, Borneo and Sulawesi)

⚡ BPSC Tip: India’s position at the junction of Palearctic and Oriental realms gives it exceptional biodiversity — remember this when answering questions on India’s ecological diversity!

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🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Biogeography and Ecology — BPSC Study Guide

World Biomes

Major Biomes:

Biome	Climate	Vegetation	Location
Tropical rainforest	Hot, wet year-round	Evergreen, 4-5 canopy layers	Amazon, Congo, SE Asia
Savanna	Warm, seasonal rainfall	Tall grasses, scattered trees	Africa, India, S America
Desert	Hot/cold, arid	Xerophytic plants, sparse	Sahara, Gobi, Atacama
Temperate forest	Moderate temperature	Deciduous/coniferous mix	E USA, W Europe, E Asia
Taiga	Cold, short summers	Coniferous (boreal forest)	N America, Russia
Tundra	Cold, permafrost	Lichens, mosses, small plants	Arctic, alpine
Mediterranean	Hot dry summer, mild wet winter	sclerophyllous vegetation	CA, Mediterranean, SW Australia

Indian Biomes:

Biome	Region	Characteristic Species
Tropical wet evergreen	Western Ghats, NE India	Dipterocarpus, orchids, ferns
Tropical semi-evergreen	Eastern Himalayas	Mixed evergreen-deciduous
Moist deciduous	Central India, E Himalayas	Sal (Shorea robusta), teak
Dry deciduous	Peninsular India	Teak, dry thorn forests
Desert/thorn	W Rajasthan	Prosopis cineraria, Acacia
Alpine	Himalayas above 3500m	Juniper, rhododendrons

Ecological Concepts

Ecosystem Components:

Abiotic Factors ← → Biotic Factors
 (light, temp,          (producers, consumers,
  water, soil)           decomposers)

Trophic Levels and Energy Flow:

Level	Organisms	Energy (%)
1st	Producers (plants)	100
2nd	Primary consumers (herbivores)	10
3rd	Secondary consumers (carnivores)	1
4th	Tertiary consumers	0.1
Decomposers	Bacteria, fungi	Variable

10% Law: Only ~10% of energy transfers between trophic levels (Lindeman’s rule)

Ecological Pyramids:

Type	Shows	Usually
Numbers	Individual count per level	Variable
Biomass	Dry weight per unit area	Upright
Energy	Energy content per unit area/time	Always upright

Biodiversity and Conservation

Biodiversity Levels:

Level	Description	Example
Genetic	Variation within species	Different varieties of rice
Species	Variety of species	100+ bird species in Western Ghats
Ecosystem	Variety of habitats	Rainforest + grassland + wetland

Biodiversity Hotspots (Critical Ecoregions):

Hotspot	Key Species	Threat
Western Ghats & Sri Lanka	Tigers, elephants, endemic frogs	Deforestation
Himalayas	Snow leopards, red pandas	Climate change
Sundarbans	Bengal tigers, mangroves	Sea level rise
Indo-Burma	Asian elephants, vultures	Agriculture

Biodiversity Richness Factors:

1. Species-area relationship: Larger area = more species
2. Latitude: Higher diversity toward equator
3. Habitat heterogeneity: Varied terrain = more niches
4. Historical stability: Less glaciation = more species
5. Productivity: More energy = more species

Conservation Strategies:

Strategy	Description	Indian Example
In-situ	Protect species in natural habitat	National parks, wildlife sanctuaries
Ex-situ	Protect outside natural habitat	Zoos, seed banks, botanical gardens
Biosphere reserves	Multiple use conservation	18 in India (e.g., Sundarbans)
Tiger reserves	Species-specific protection	50+ reserves in India

⚡ BPSC PYQ: “Discuss the concept of biodiversity hotspots and their significance for conservation” Answer: Biodiversity hotspots are regions with high species endemism and significant habitat loss. India has two global hotspots: Western Ghats-Sri Lanka and Himalayas-Indo-Burma. Conservation is critical as these areas contain irreplaceable genetic resources and endemic species found nowhere else.

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🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Biogeography and Ecology — Comprehensive BPSC Notes

Island Biogeography (MacArthur-Wilson Theory)

Theory: Species richness on islands reaches equilibrium between colonization (immigration) and extinction rates.

Factors Affecting Island Species Richness:

Factor	Effect
Island size	Larger = more species (more habitats, lower extinction)
Distance from mainland	Closer = more colonization
Habitat diversity	More varied habitats = more species
Time	Equilibrium takes 10⁴-10⁶ years

Equilibrium Model: $$S = \frac{cA}{2\pi D + A}$$ S = species richness, A = area, D = distance, c = constant

Application to Conservation:

• Larger reserves better than fragmented small ones
• Corridids between reserves help species movement
• Edge effects reduce interior habitat quality

Ecological Adaptations

Plant Adaptations:

Environment	Adaptation	Example
Desert	Deep roots, water storage, spines	Cactus, Prosopis
Wetland	Aerenchyma (air tissue), buttress roots	Mangroves, papyrus
Alpine	Low growth form, antifreeze compounds	Saxifraga
Coastal salt	Halophytes, salt excretion	Salicornia, Avicennia

Animal Adaptations:

Environment	Adaptation	Example
Desert	Nocturnal, water conservation	Fennec fox, camel
Arctic	Insulation (fat, fur), hibernation	Polar bear, arctic fox
Marine	Streamlined body, blubber	Dolphins, seals
Forest canopy	Prehensile limbs, vocalizations	Primates, birds

Mimicry Types:

Type	Description	Example
Batesian	Harmless mimics harmful	Non-poisonous butterflies look like toxic
Müllerian	Two harmful species resemble each other	Bees and wasps
Cryptic	Blending with environment	Stick insects, leaf insects

Soil Geography

Soil-Forming Factors (Jenny’s Equation): $$S = f(cl, o, r, p, t)$$ S = soil, cl = climate, o = organisms, r = relief, p = parent material, t = time

Soil Profile Horizons:

Horizon	Description
O	Organic layer (litter)
A	Topsoil (organic-mineral, biological activity)
E	Eluviation (leaching zone)
B	Subsoil (illuviation, accumulation)
C	Parent material (weathered rock)
R	Bedrock

Indian Soil Types:

Soil	Formation	Distribution	Limitation
Alluvial	River deposition	Indo-Gangetic plain, Bihar	Low organic matter
Black (Vertisol)	Basalt weathering	Deccan plateau (MP, Maharashtra)	Poor drainage, cracking
Red	Granite/gneiss weathering	Eastern Ghats, Peninsular	Low fertility
Laterite	Heavy rainfall leaching	Western Ghats, NE highlands	Acidic, low fertility
Desert	Arid weathering	W Rajasthan	Sand dune, salt
Forest	Mountain weathering	Himalayas	Variable

Soil Degradation:

Process	Causes	Extent
Erosion	Water, wind, deforestation	150 million ha in India
Salinization	Improper irrigation	6-7 million ha
Waterlogging	Excessive irrigation	Significant
Nutrient depletion	Continuous cropping	Wide

Bihar’s Soil:

• Alluvial soils dominate (recent, fertile)
• Calcareous concretions (kankar) in some areas
• Flooding deposits fresh silt
• Phosphorus and nitrogen deficiencies common

Conservation in India

Protected Area Network (2023):

Category	Number	Area
National Parks	106	44,403 km²
Wildlife Sanctuaries	573	67,415 km²
Tiger Reserves	54	75,796 km²
Biosphere Reserves	18	1,02,415 km²
RAMSAR Sites	80	1.3 million ha

Important Species Conservation:

Species	Status	Conservation Program
Bengal Tiger	Endangered	Project Tiger (since 1973)
Asian Elephant	Endangered	Project Elephant (1991)
One-horned Rhino	Vulnerable	Kaziranga, Pobitora
Ganges River Dolphin	Endangered	Conservation in river systems
Sea Turtle	Various	Coastal protection
Great Indian Bustard	Critically Endangered	Desert National Park

Wildlife Protection Act 1972 (as amended 2022):

• Schedule I: Absolute protection (tiger, elephant, rhino)
• Schedule II: Protection with penalties
• Schedule III-IV: Game animals
• Schedule V: Vermin

Biodiversity Act 2002:

• Establishes Biodiversity Councils
• Regulates access to biological resources
• Benefit sharing with local communities
• Recognizes traditional knowledge

⚡ BPSC Strategy: Environmental geography integrates ecology, conservation, and human impact. Bihar-specific questions often focus on floodplain ecology, river dolphin conservation, and agricultural sustainability.

⚡ Common BPSC Questions:

1. “Explain the distribution of world biomes with reference to climate” (12 marks)
2. “Discuss India’s biodiversity hotspots and conservation measures” (15 marks)
3. “Describe the ecological adaptations of plants and animals in different environments” (10 marks)
4. “Explain soil-forming processes and the major soil types of India” (12 marks)

⚡ Bihar-specific Focus: Understand the ecological significance of Bihar’s wetlands (Kabar Lake), riverine ecosystems (Ganges dolphin), and the impact of floods on soil fertility and agricultural patterns.

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