Elaborate Notes
Introduction to Biogeography and India’s Classification
Biogeography is the scientific discipline that investigates the distribution of species, organisms, and ecosystems in geographic space and through geological time. It seeks to understand the factors—both historical (e.g., plate tectonics, evolution) and ecological (e.g., climate, habitat)—that determine the composition and distribution of life. The biogeographic classification of India is a framework developed to delineate distinct regions based on their unique flora, fauna, and ecosystem characteristics. The most widely accepted classification was proposed by W.A. Rodgers and H.S. Panwar in 1988 for the Wildlife Institute of India (WII), which divides the country into 10 biogeographic zones. This classification serves as a crucial tool for conservation planning and biodiversity management.
A) Trans-Himalayan Zone
- Geographical Extent and Topography: This zone represents an extension of the Tibetan Plateau and is located to the north of the Great Himalayan range. It encompasses the high-altitude, cold, and arid regions of Ladakh, parts of northern Kashmir, and the Lahaul and Spiti valleys of Himachal Pradesh, along with northern Sikkim. The topography is dominated by rugged, high-elevation mountain ranges like the Karakoram, Ladakh, and Zanskar. Due to its location in the rain-shadow of the Himalayas, it receives very low precipitation (less than 100 mm annually), qualifying it as a “cold desert.” Temperatures are extreme, with long, harsh winters. Cloudbursts, though rare, can occur, causing flash floods in the narrow valleys due to the steep and barren terrain being unable to absorb sudden, intense rainfall. Strong aeolian (wind-based) erosion in this dry landscape leads to the formation of sand dunes in some areas, such as the Nubra Valley.
- Vegetation: The vegetation is sparse and xerophytic, adapted to the extreme cold and arid conditions. Plant life is largely confined to riverbanks and sheltered valleys. It consists primarily of alpine and steppe vegetation, including dwarf junipers, Rhododendrons, and various herbaceous plants. The flora shows a high affinity with the Tibetan Plateau.
- Fauna: The fauna is also adapted to the harsh conditions and shows strong similarities to that of Central Asia.
- Double-humped Camel (Bactrian Camel): Found in the Nubra Valley, these are remnants of the ancient Silk Route trade caravans.
- Snow Leopard (Panthera uncia): This elusive apex predator is the flagship species of the region. Its conservation status is ‘Vulnerable’ on the IUCN Red List. India launched Project Snow Leopard in 2009 for its conservation.
- Yak (Bos grunniens): Both wild and domesticated varieties are found. They are integral to the local pastoral economy for milk, wool, and transport.
- Tibetan Antelope or Chiru (Pantholops hodgsonii): Hunted for its extremely fine wool, known as shahtoosh, which led to a drastic decline in its population. International trade in shahtoosh is banned under CITES.
- Changthangi Goat: A special breed of goat from which the famous Pashmina wool is sourced. It is reared by the nomadic Changpa tribe of the Changthang plateau in eastern Ladakh, who practice a unique form of transhumance pastoralism.
- Tibetan Wild Ass (Kiang): A large equid found in the high-altitude grasslands and steppe environments.
- Black-necked Crane: A ‘Near Threatened’ species, this is a migratory bird that breeds in the high-altitude wetlands of Ladakh.
- Protected Areas:
- Hemis National Park: Located in Ladakh, it is the largest national park in India. It is globally famous for its high density of snow leopards.
- Pin Valley National Park: Situated in the Lahaul and Spiti district of Himachal Pradesh, it is part of the Cold Desert Biosphere Reserve.
B) Himalayan Zone
- Topography and Climate: This zone includes the entire Himalayan mountain chain from Jammu and Kashmir in the west to Arunachal Pradesh in the east. It is characterized by a massive variation in elevation (from foothills at 1000 m to peaks over 8000 m), resulting in a wide range of climatic conditions and vegetation types. Unlike the Trans-Himalayan zone, the southern slopes receive high rainfall from the monsoon winds. The geology is young and unstable, making the region prone to tectonic activities like earthquakes and landslides.
- Vegetation: The vegetation is distinctly demarcated by elevation, a phenomenon known as altitudinal zonation.
- Tropical/Sub-tropical (Foothills): Moist deciduous forests with species like Sal.
- Temperate (1000-2500 m): Broad-leaved forests of Oak and coniferous forests of Chir Pine.
- Sub-alpine (2500-4000 m): Dominated by conifers like Fir, Spruce, and Deodar, with extensive growths of Rhododendron.
- Alpine (>4000 m): Above the treeline, this zone features alpine meadows, known as Bugyals in Uttarakhand and Margs in Kashmir. These meadows are used for summer grazing by pastoral communities like the Gujjars and Bakarwals, who practice transhumance.
- Fauna: The faunal diversity is rich and varies with altitude.
- Snow Leopard and Himalayan Brown Bear: Found in the upper reaches.
- Kashmir Stag (Hangul): A ‘Critically Endangered’ subspecies of the Red Deer, found exclusively in Dachigam National Park. Project Hangul is a dedicated conservation program.
- Himalayan Tahr: A wild goat adapted to rocky, mountainous terrain.
- Musk Deer: An endangered species poached for its musk pod, used in perfumes and traditional medicine.
- Red Panda: An ‘Endangered’, arboreal mammal found in the temperate bamboo forests of the Eastern Himalayas (Sikkim, Arunachal Pradesh).
- Asiatic Elephant: Found in the Shivalik foothills, particularly in areas like Rajaji National Park.
- Protected Areas:
- Dachigam National Park (J&K): The last remaining habitat of the Hangul.
- Nanda Devi Biosphere Reserve (Uttarakhand): A UNESCO World Heritage Site, comprising Nanda Devi and Valley of Flowers National Parks.
- Valley of Flowers National Park (Uttarakhand): Famous for its meadows of endemic alpine flowers.
- Namdapha National Park (Arunachal Pradesh): Unique for harbouring four species of large cats: Tiger, Leopard, Clouded Leopard, and Snow Leopard, due to its vast altitudinal variation.
- Dihang-Dibang Biosphere Reserve (Arunachal Pradesh): A major biodiversity hub in the Eastern Himalayas.
C) Gangetic Plains
- Area and Characteristics: This zone covers one of the most fertile regions of the world, formed by alluvial deposits from the Ganga and its tributaries. It extends across Uttar Pradesh, Bihar, parts of Jharkhand, and West Bengal. The plains are largely flat and have been extensively modified by agriculture for centuries, leading to severe habitat destruction. The climate is extreme (continental), with very hot summers and cold winters. Precipitation decreases from east (moist) to west (drier), influencing the forest types.
- Vegetation: The original vegetation was deciduous forest, which now exists in fragmented patches. Both moist deciduous (in the east) and dry deciduous (in the west) forests are found. Key tree species include Sal (Shorea robusta), Teak (Tectona grandis), and Sheesham (Dalbergia sissoo).
- Fauna: The fauna is adapted to riverine and plain ecosystems.
- Tiger: Found in the Terai region’s protected areas.
- One-horned Rhinoceros: While 90% of its population is in Assam, a small population exists in Dudhwa National Park (UP) and Valmiki Tiger Reserve (Bihar).
- Gangetic Dolphin (Platanista gangetica): India’s National Aquatic Animal, it is an indicator of river health and is listed as ‘Endangered’.
- Ungulates: Includes Nilgai, Chinkara, Blackbuck, and Swamp Deer (Barasingha).
- Reptiles: The Gharial (Critically Endangered) and Mugger crocodile are found in rivers like the Ganga and Chambal.
- Saras Crane: The world’s tallest flying bird, found in wetlands and agricultural fields. It is listed as ‘Vulnerable’.
- Protected Areas:
- Jim Corbett National Park (Uttarakhand): Established in 1936 as Hailey National Park, it is India’s first national park. It was also the launch site for Project Tiger in 1973.
- Dudhwa National Park (UP): A key habitat for the Swamp Deer and tigers.
- Valmiki National Park (Bihar): The only tiger reserve in the state.
- Vikramshila Gangetic Dolphin Sanctuary (Bihar): India’s first and only dolphin sanctuary, designated to protect the Gangetic Dolphin.
D) Semi-Arid Zone
- Regions and Characteristics: This is a transitional zone between the arid desert of the west and the moist Gangetic plains and Deccan plateau. It includes eastern Rajasthan, eastern Gujarat, and the Malwa plateau of Madhya Pradesh. The region is characterized by grasslands and discontinuous patches of tropical thorn forests.
- Vegetation: The dominant vegetation is tropical thorn forest, characterized by xerophytic species like Babul (Acacia sp.) and Khejri, interspersed with savannah grasslands.
- Fauna: This zone historically supported a wide range of large mammals.
- Big Cats: The region is noted for the presence of multiple large carnivores. The Asiatic Lion is found in Gujarat, leopards are widespread, and tigers are found in reserves like Sariska and Ranthambore. The extinct Asiatic Cheetah is being replaced by the African Cheetah, reintroduced in Kuno Palpur National Park.
- Great Indian Bustard (GIB): A ‘Critically Endangered’ bird, it is one of the heaviest flying birds in the world. Its grassland habitat is under severe threat.
- Ungulates: Blackbuck and Chinkara are commonly found.
- Protected Areas:
- Kuno Palpur National Park (MP): Selected as the site for India’s Cheetah Reintroduction Project.
- Sariska Tiger Reserve (Rajasthan): An important tiger habitat.
- Keoladeo National Park (Rajasthan): A UNESCO World Heritage Site, formerly known as Bharatpur Bird Sanctuary, it is a world-famous wetland for migratory birds.
E) Desert Zone
- Regions and Topography: This zone corresponds to the Thar Desert and covers western Rajasthan and parts of Gujarat, including the Rann of Kutch. The climate is extremely arid, with annual precipitation below 25 cm. The landscape features vast sand dunes in western Rajasthan, known as the Marusthal. Large saline depressions or salt pans are also characteristic, especially in the Rann of Kutch.
- Vegetation: The flora is xerophytic, adapted to survive in extreme heat and water scarcity, with species like cactus, Khejri, and thorny shrubs. Near the Kutch region, the Banni Grasslands represent one of Asia’s largest tropical grassland ecosystems, supporting a unique pastoralist culture.
- Fauna: The fauna is highly adapted to desert conditions.
- Asiatic Wild Ass: Its last remaining population is found exclusively in the Wild Ass Sanctuary in the Little Rann of Kutch.
- Great Indian Bustard: Desert National Park is one of its last strongholds.
- Blackbuck, Chinkara, and Desert Fox are other notable species.
- Kharai Camels: A unique breed found in the coastal areas of Kutch, they are known as “swimming camels” due to their ability to swim through seawater to graze on mangroves.
- Protected Areas:
- Desert National Park (Rajasthan): A vast park protecting the GIB and other desert fauna.
- Wild Ass Sanctuary (Gujarat): Located in the Little Rann of Kutch, dedicated to the conservation of the Asiatic Wild Ass.
F) Western Ghats
- Region and Characteristics: A mountain range running parallel to the western coast of India, starting south of the Tapti River in Gujarat and extending to Kanyakumari in Tamil Nadu. The Western Ghats are a UNESCO World Heritage Site and one of the world’s eight “hottest” biodiversity hotspots. They create a barrier for the southwest monsoon winds, causing immense orographic precipitation on their western slopes, while creating a rain-shadow effect on the Deccan plateau to their east. This climatic variation results in exceptional biodiversity. The high-altitude ecosystem, comprising unique tropical montane forests interspersed with natural grasslands, is known as the Shola-Grassland complex.
- Flora: The region boasts incredible plant diversity with high endemism.
- Evergreen and Semi-evergreen forests are dominant.
- Neelakurinji (Strobilanthes kunthiana): A shrub famous for its mass flowering once every 12 years, carpeting the hillsides of the Nilgiris in blue.
- Red Sandalwood (Pterocarpus santalinus): It is important to note that this species is endemic to and primarily found in the Seshachalam hills of the Eastern Ghats in Andhra Pradesh, not the Western Ghats.
- Fauna: The fauna is characterized by a very high degree of endemism.
- Lion-tailed Macaque: An ‘Endangered’ primate, endemic to the evergreen forests of the Western Ghats. Its presence indicates a healthy forest ecosystem.
- Nilgiri Tahr: The state animal of Tamil Nadu, this endangered mountain goat is endemic to the grassy cliffs of the Nilgiri Hills.
- Malabar Civet: A ‘Critically Endangered’ and possibly extinct mammal endemic to this region.
- Other Endemics: Malabar Giant Squirrel, Flying Lizard, and numerous species of amphibians and reptiles.
- Large Mammals: The region supports significant populations of the Asiatic Elephant, Tiger, Leopard, and Gaur.
- King Cobra: The world’s longest venomous snake, found in abundance in the dense forests.
- Mahseer: A large freshwater fish, often called the “tiger of the water,” is an important species in the rivers of the Western Ghats.
- Protected Areas: This zone has a network of contiguous protected areas forming large conservation landscapes.
- Nilgiri Biosphere Reserve: The first biosphere reserve in India, it includes protected areas like Nagarhole and Bandipur National Parks (Karnataka), Mudumalai Tiger Reserve (Tamil Nadu), and Wayanad Wildlife Sanctuary (Kerala). This landscape supports one of the highest densities of tigers and elephants in India.
- Silent Valley National Park (Kerala): Known for its pristine tropical evergreen rainforest and being a stronghold for the Lion-tailed Macaque.
- Periyar Tiger Reserve (Kerala): An important elephant and tiger reserve.
- Kudremukh National Park (Karnataka): Protects a large stretch of the Shola-Grassland ecosystem.
Prelims Pointers
- Biogeographic Zones in India: 10, based on the classification by Rodgers & Panwar (1988) for the Wildlife Institute of India (WII).
- Largest National Park: Hemis National Park, Ladakh.
- First National Park: Jim Corbett National Park (established 1936 as Hailey National Park).
- First Tiger Reserve: Jim Corbett National Park, where Project Tiger was launched in 1973.
- Cold Desert Biosphere Reserve: Includes Pin Valley National Park in Himachal Pradesh.
- UNESCO World Heritage Sites (Natural): Western Ghats, Nanda Devi and Valley of Flowers National Parks, Keoladeo National Park.
- National Aquatic Animal of India: Gangetic River Dolphin (Platanista gangetica).
- Cheetah Reintroduction Site: Kuno Palpur National Park, Madhya Pradesh.
- Exclusive home of Asiatic Wild Ass: Wild Ass Sanctuary, Little Rann of Kutch, Gujarat.
- Exclusive home of Kashmir Stag (Hangul): Dachigam National Park, J&K.
- Pashmina Wool Source: Changthangi goat, reared by Changpa nomads in Ladakh.
- Shahtoosh Wool Source: Tibetan Antelope (Chiru).
- Swimming Camels: Kharai Camels, found in Kutch, Gujarat.
- Mass flowering plant: Neelakurinji, flowers once every 12 years in the Western Ghats.
- Tallest flying bird: Saras Crane.
- Heaviest flying bird: Great Indian Bustard.
- State Animal of Tamil Nadu: Nilgiri Tahr.
- Critically Endangered Species Mentioned: Kashmir Stag (Hangul), Great Indian Bustard, Malabar Civet, Gharial.
- Endangered Species Mentioned: Tiger, Lion-tailed Macaque, Red Panda, Nilgiri Tahr, Gangetic Dolphin.
Mains Insights
1. Interplay of Physiography and Biodiversity (GS Paper I)
- Cause-Effect Relationship: The biogeographic zones of India are a direct manifestation of its diverse physiography and climate.
- Himalayan Orogeny: The Himalayas act as a massive climatic barrier, creating the arid, cold desert of the Trans-Himalayan zone in its rain-shadow and the high-rainfall, lush Himalayan zone on its windward side. This altitudinal variation creates distinct vertical ecosystems, from tropical forests to alpine meadows.
- Alluvial Plains: The fertile Gangetic plains, formed by river deposition, supported rich biodiversity. However, this same fertility led to intensive agriculture and high population density, making it one of the most altered biogeographic zones with fragmented habitats confined to protected areas.
- Orographic Rainfall: The Western Ghats intercept the monsoon winds, leading to high precipitation and dense evergreen forests on the western slopes, contrasting sharply with the semi-arid rain-shadow region of the Deccan plateau on the eastern side. This sharp climatic gradient has driven the evolution of a high number of endemic species.
2. Human-Environment Interaction and Livelihoods (GS Paper I & III)
- Adaptation and Co-existence: Different zones showcase unique patterns of human adaptation.
- Pastoralism: In the Trans-Himalayan and Himalayan zones, communities like the Changpas (rearing Pashmina goats) and Gujjars (practicing transhumance in Bugyals) have livelihoods deeply integrated with the fragile ecosystem. Their traditional practices are often sustainable.
- Conflict: In zones like the Gangetic plains and Western Ghats, high population density and resource extraction (agriculture, mining, infrastructure) have led to severe human-wildlife conflict, habitat fragmentation, and pollution (e.g., industrial effluents in the Ganga affecting dolphins).
- Historiographical Viewpoint: Early conservation models often viewed human presence as detrimental (“fortress conservation”). However, modern conservation biology increasingly recognizes the role of indigenous and local communities (e.g., the Bishnois of Rajasthan protecting Blackbucks) as crucial partners in biodiversity conservation, promoting models of co-management and sustainable livelihoods.
3. Conservation Strategies and Challenges (GS Paper III)
- Zone-Specific Challenges: A biogeographic approach helps tailor conservation policies.
- Trans-Himalaya: The primary threat is climate change, leading to glacial melt and changing water regimes. Human-wildlife conflict (Snow Leopard predation on livestock) and infrastructure development are other major concerns.
- Western Ghats: Faces threats from habitat fragmentation due to plantations (tea, coffee), mining, and linear infrastructure (roads, railways) that disrupt wildlife corridors essential for species like elephants and tigers.
- Desert & Semi-Arid: The major challenge is the degradation of grasslands due to overgrazing and conversion to agriculture, which directly threatens species like the Great Indian Bustard.
- Significance of the Classification:
- Ecosystem Approach: This classification shifts the focus from conserving single species to conserving entire ecosystems and landscapes.
- Prioritization: It helps identify regions with high endemism and biodiversity, like the Western Ghats and Himalayas (global biodiversity hotspots), allowing for the prioritization of conservation funds and efforts.
- Gap Analysis: It is used to analyze the protected area (PA) network to identify and bridge gaps, ensuring all unique ecosystems are adequately represented and conserved. This was the basis for creating new PAs and Biosphere Reserves.