5. New Environment Notes 08

Elaborate Notes

BIOGEOGRAPHIC REGIONS

The classification of India into biogeographic regions is a systematic framework to understand the distribution of flora and fauna. The most widely accepted classification was proposed by H.S. Panwar and W.A. Rodgers of the Wildlife Institute of India in 1988, dividing the country into 10 zones. The summary discusses three of these zones in detail.

• Deccan Plateau:

  • Geographical Extent and Significance: The Deccan Plateau is Biogeographic Zone 6 and is indeed the most extensive zone, covering approximately 43% of India’s total land area. It is a vast triangular plateau, bounded by the Satpura and Vindhya Ranges in the north, and the Eastern and Western Ghats on its respective flanks. It encompasses a major portion of peninsular India, including the states of Maharashtra, Karnataka, Andhra Pradesh, Telangana, and parts of Madhya Pradesh, Chhattisgarh, Tamil Nadu, Jharkhand, and Odisha.
  • Geology and Topography: The region is primarily composed of ancient, hard crystalline rocks of the Archaean and Dharwar systems. The northwestern part is characterized by Deccan Traps, which are vast formations of basaltic lava flows from the Cretaceous-Eocene period, resulting in a distinct rolling topography and black cotton soil (regur).
  • Climatic Conditions: The region experiences a tropical climate with distinct wet and dry seasons. The temperature remains high throughout the year, especially in the pre-monsoon summer. The annual precipitation, ranging from 500 mm to 2000 mm (50 cm - 200 cm), is largely received from the South-West Monsoon. The Western Ghats create a significant rain-shadow effect, making the central parts of the plateau relatively arid.
  • Vegetation: The vegetation is a direct reflection of the rainfall gradient.
    • Tropical Moist Deciduous Forests: Found in areas with higher rainfall (100-200 cm), characterized by trees that shed their leaves in the dry season. Dominant species include Teak (Tectona grandis) and Sal (Shorea robusta).
    • Tropical Dry Deciduous Forests: Found in areas with moderate rainfall (70-100 cm). Key species include Tendu (Diospyros melanoxylon), Palash (Butea monosperma), and Khair (Acacia catechu).
    • Tropical Thorn Forests and Scrublands: Prevalent in the arid rain-shadow areas (<70 cm rainfall). Vegetation is dominated by xerophytic species like Babul (Acacia nilotica) and various thorny shrubs.
    • Endemic Species: The region is home to unique species like Red Sanders (Pterocarpus santalinus), which is endemic to a specific tract of forest in the Eastern Ghats of Andhra Pradesh.
  • Wildlife and Conservation: The diverse habitats support a rich faunal diversity.
    • Key Species: It is a critical habitat for the Tiger (Panthera tigris), Asiatic Elephant (Elephas maximus), and the Indian Bison or Gaur (Bos gaurus). The semi-arid grasslands are home to the Blackbuck (Antilope cervicapra) and the Great Indian Bustard (Ardeotis nigriceps), a critically endangered bird. The Swamp Deer or Barasingha (Rucervus duvaucelii), particularly the hard-ground subspecies, is famously conserved in Kanha National Park.
    • Protected Areas: This zone has a dense network of Protected Areas (PAs). Nagarjunasagar-Srisailam Tiger Reserve in Andhra Pradesh and Telangana is the largest tiger reserve in India by core area. Kanha and Bandhavgarh National Parks in Madhya Pradesh are renowned for their high tiger densities. Melghat Tiger Reserve in Maharashtra is notable; the Lonar crater, a National Geo-heritage monument, is situated nearby, though not within the reserve itself. Pachmarhi and Achanakmar-Amarkantak are crucial Biosphere Reserves under the UNESCO Man and the Biosphere (MAB) Programme.

• North-East Biogeographic Region:

  • Geographical Context: This region, part of Biogeographic Zone 9, is a meeting point of the Indian, Indo-Malayan, and Indo-Chinese biogeographical realms. Its unique location and topography make it a global biodiversity hotspot (part of the Indo-Burma and Himalaya hotspots).
  • Topography and Climate: It is predominantly a hilly and mountainous region, with the exception of the Brahmaputra and Barak river valleys (Assam plains). The climate is humid subtropical, heavily influenced by the Bay of Bengal branch of the monsoon, leading to very high annual precipitation, often exceeding 2000 mm (200 cm).
  • Biodiversity and Endemism: The region’s isolation and varied habitats have resulted in high levels of biodiversity and endemism. It is considered a cradle of flowering plants.
  • Vegetation: The vegetation ranges from tropical to alpine.
    • Tropical Wet Evergreen Forests: Found in the lower reaches, characterized by a dense canopy and rich species diversity.
    • Semi-Evergreen and Moist Deciduous Forests: Occur at moderate elevations.
    • Specialized Flora: The region is known for its extensive Bamboo (Bambusa spp.) forests, which are crucial for the local economy and ecology. It is also home to several species of insectivorous plants like the Pitcher Plant (Nepenthes khasiana), which is endemic to the Khasi hills of Meghalaya.
  • Wildlife and Conservation:
    • Key Species: It is a stronghold for the Greater One-horned Rhinoceros (Rhinoceros unicornis), with over 90% of its global population in Assam, primarily in Kaziranga National Park. It is the only region in India to host all three types of Indian Bustards, including the Bengal Florican (Houbaropsis bengalensis). The Sangai or Dancing Deer (Rucervus eldii eldii), the state animal of Manipur, is found only on the floating biomass (Phumdis) of Loktak Lake. Other notable species include the Red Panda (Ailurus fulgens), Hoolock Gibbon (Hoolock hoolock - India’s only ape), and the Pygmy Hog (Porcula salvania - the world’s smallest wild pig).
    • Protected Areas: Kaziranga National Park is a UNESCO World Heritage Site, celebrated for its success in rhino conservation. Manas National Park is also a UNESCO World Heritage Site, a Tiger Reserve, and a Biosphere Reserve. Keibul Lamjao National Park is the world’s only floating national park, designated to protect the Sangai deer. Pobitora Wildlife Sanctuary is known for having one of the highest densities of the one-horned rhino.

• Coastal and Islands Biogeographic Regions:

  • Geographical Features: This includes two distinct zones: The Coasts (Zone 7) and The Islands (Zone 10). The coasts are characterized by low elevation plains, estuaries, deltas, and brackish water ecosystems like lagoons and mangroves. The islands include the Andaman & Nicobar archipelago in the Bay of Bengal and the Lakshadweep archipelago in the Arabian Sea.
  • Vegetation and Ecosystems:
    • Coastal Vegetation: The vegetation varies significantly. The high rainfall Western Coast supports Semi-Evergreen forests. The Coromandel Coast, which receives rainfall primarily from the retreating monsoon, has unique Dry Evergreen forests.
    • Mangroves: These are salt-tolerant forest ecosystems found in intertidal zones of river deltas and estuaries. The Sundarbans in the Ganges-Brahmaputra delta is the largest single block of mangrove forest in the world.
    • Coral Reefs: India has four major coral reef areas: the Gulf of Kutch, Gulf of Mannar, Lakshadweep Islands, and Andaman & Nicobar Islands. They are often called the “rainforests of the sea” for their immense biodiversity. Their absence along the eastern mainland coast is largely due to high freshwater influx and sediment discharge from large river deltas.
    • Island Vegetation: The Andaman Islands are characterized by Tropical Wet Evergreen and Semi-Evergreen forests, reflecting high rainfall.
  • Geological Features: The Andaman & Nicobar Islands are of volcanic origin, representing a submerged mountain range. Barren Island is India’s only confirmed active volcano, with its last eruption recorded in recent years. Narcondam Island is a dormant volcano.
  • Wildlife and Conservation:
    • Coastal Fauna: The Sundarbans is the only mangrove forest in the world inhabited by the Royal Bengal Tiger (Panthera tigris tigris). The coasts are critical nesting sites for sea turtles, especially the Olive Ridley Turtle (Lepidochelys olivacea) at sites like Gahirmatha in Odisha. The Fishing Cat (Prionailurus viverrinus) is a wetland specialist found in the mangroves. The Dugong or Sea Cow (Dugong dugon) is a vulnerable marine mammal found in the Gulf of Mannar and Andaman waters.
    • Island Fauna: The isolation of the islands has led to high endemism. Key species include the Saltwater Crocodile (Crocodylus porosus), the critically endangered Nicobar Megapode (Megapodius nicobariensis), and the Giant Leatherback Sea Turtle (Dermochelys coriacea).
    • Protected Areas: Sundarbans is a Tiger Reserve, Biosphere Reserve, National Park, and a UNESCO World Heritage Site. The Gulf of Mannar Biosphere Reserve is the first Marine Biosphere Reserve in South & South-East Asia. Bhitarkanika National Park is known for its large population of Saltwater Crocodiles and mangrove diversity.

BIODIVERSITY LOSS

Biodiversity loss refers to the decline in the number, genetic variability, and variety of species, and the biological communities in a given area. The “Evil Quartet” is a term coined by biologist Jared Diamond to describe the four main causes of biodiversity loss: Habitat Loss, Over-exploitation, Introduced Species, and Co-extinctions. The summary covers several of these critical factors.

• i) Habitat Loss:

  • This is considered the primary driver of biodiversity loss globally. It involves the complete destruction of a habitat (e.g., deforestation for agriculture) or its degradation and fragmentation, which reduces its capacity to support native species.
  • Forest Fires: These are a significant cause of habitat degradation.
    • Ecological Impact: While some ecosystems are fire-adapted, intense and frequent fires can destroy vegetation cover, expose topsoil to erosion, and kill wildlife directly or through habitat destruction.
    • Favorable Conditions: Dry seasons (winter and summer) in deciduous and thorn forests, where there is an accumulation of dry leaf litter, are highly susceptible. The presence of species like Chir Pine (Pinus roxburghii) in the Himalayas increases fire risk due to flammable resin and needle litter.
    • Types of Fires: Crown fires are the most destructive, burning through the top layer of foliage on a tree. Ground fires burn the organic matter in the soil beneath the surface litter. Bush fires are a general term, famously used in Australia, for fires in scrubland or forests.
    • Causes: Natural causes are less frequent than anthropogenic ones. Unintentional fires from discarded cigarettes or sparks from power lines are common. Intentional fires are often linked to shifting cultivation (Jhum), clearing land for encroachment, or by poachers to divert forest staff. According to the Forest Survey of India’s (FSI) State of Forest Report, a significant percentage of India’s forest cover is prone to fires.
    • Management: Management involves a three-pronged strategy: prevention (awareness, creating fire lines), detection (watchtowers, satellite monitoring), and suppression (controlled burning, modern firefighting equipment).

• ii) Overexploitation:

  • This occurs when a renewable resource is harvested at a rate faster than it can be regenerated. It stems from the “Tragedy of the Commons” principle described by ecologist Garrett Hardin (1968), where shared resources are depleted by individuals acting in their own self-interest.
  • Examples: Overfishing, particularly with destructive methods like bottom trawling, has led to the collapse of many marine fish stocks. The historical hunting of the Asiatic Cheetah led to its extinction in India in the 1950s. The illegal wildlife trade for products like ivory, rhino horn, and tiger parts continues to threaten many species. Overgrazing degrades grasslands, and excessive extraction of groundwater depletes aquifers, impacting entire ecosystems.

• iii) Pollution:

  • Pollutants can have direct lethal effects or sublethal effects that degrade habitat quality and affect the physiological functions of organisms.
  • Water Pollution: Eutrophication, caused by nutrient runoff (nitrates and phosphates) from agriculture and sewage, leads to algal blooms. When these algae die and decompose, they deplete dissolved oxygen, creating “dead zones” (hypoxia) that kill fish and other aquatic life. The Gangetic Dolphin (Platanista gangetica) is threatened by pollutants like organochlorides from industrial waste.
  • Air Pollution: Acid rain, formed from sulfur and nitrogen oxides, can acidify soils and water bodies, harming forests and aquatic life. Lichens are excellent bio-indicators as they are highly sensitive to sulfur dioxide and do not grow in polluted air.
  • Light and Radiation Pollution: Artificial light at night can disrupt the nocturnal behaviour, reproduction, and migration patterns of many species, such as sea turtles. Studies have suggested a correlation between electromagnetic radiation from mobile towers and the decline of House Sparrow (Passer domesticus) populations in urban areas.

• iv) Climate Change:

  • This acts as a global stressor, exacerbating the effects of other threats.
  • Global Warming: Rising sea surface temperatures are the primary cause of mass coral bleaching, where corals expel their symbiotic algae (zooxanthellae) and turn white, often leading to mortality.
  • Ocean Acidification: As the ocean absorbs excess atmospheric CO2, its pH decreases. This impairs the ability of marine organisms like corals, molluscs, and plankton to build their calcium carbonate shells and skeletons.
  • Range Shifts: Species are forced to shift their geographical ranges towards the poles or higher altitudes to track suitable climatic conditions. This can lead to local extinctions and disruptions in ecological communities. Polar ecosystems (affecting polar bears) and high-altitude Taiga forests are particularly vulnerable. As per reports by the Intergovernmental Panel on Climate Change (IPCC), climate change is projected to become a dominant driver of biodiversity loss in the coming decades.

Prelims Pointers

• Deccan Plateau is the largest biogeographic region of India.
• States covered by Deccan Plateau: Karnataka, Tamil Nadu, Andhra Pradesh, Madhya Pradesh, Telangana, Maharashtra, Chhattisgarh, Jharkhand, Odisha.
• Vegetation in Deccan Plateau: Tropical moist and dry deciduous, tropical thorn, grasslands.
• State Animal of Andhra Pradesh: Blackbuck.
• State Animal of Madhya Pradesh: Swamp Deer (Barasingha).
• Largest Tiger Reserve in India (by area): Nagarjunasagar-Srisailam Tiger Reserve.
• Melghat Tiger Reserve is located in Maharashtra.
• The North-East biogeographic region exhibits high endemism.
• Pitcher plant (a carnivorous plant) is found in the North-East.
• State Animal of Sikkim: Red Panda.
• Sangai Deer (Dancing Deer) is found on Phumdis (floating biomass) in Manipur’s Loktak Lake.
• Bengal Florican is a bustard bird found in India.
• Hoolock Gibbon is India’s only ape.
• FSSAI has recognized Mithun as a ‘food animal’.
• Pobitora Wildlife Sanctuary in Assam has a very high density of one-horned rhinoceros.
• India’s four major coral reef patches are: Andaman & Nicobar islands, Lakshadweep, Gulf of Mannar, and Gulf of Kutch.
• Coral reefs are largely absent on the eastern mainland coast of India.
• Narcondam (dormant) and Barren (active) are volcanic islands in the Andaman Sea.
• State animal of West Bengal: Fishing Cat.
• Dugong is also known as the ‘Sea Cow’.
• The Nicobar Megapode is a critically endangered bird.
• Forest fires are most common in the Western Ghats and Uttarakhand.
• Types of forest fire: Crown fire, Ground fire, and Bush fire.
• Lichens are sensitive to air pollution and act as bio-indicators.
• Radiation from cell phone towers has been linked to the decline in the number of house sparrows.
• Coral bleaching is caused by rising sea temperatures due to global warming.

Mains Insights

Biogeographic Classification and Conservation Strategy

• Significance of Classification: The biogeographic classification by Rodgers and Panwar (1988) provides a scientific basis for conservation planning. Its primary goal was to establish a representative network of protected areas (PAs) that covers all of India’s diverse ecosystems. This ensures that conservation efforts are not just focused on charismatic megafauna (like tigers) but also on protecting unique habitats and their entire biological communities.
• Conservation Gaps and Priorities: By mapping PAs against these zones, planners can identify “gaps” – ecosystems that are under-represented in the network. For instance, some grassland ecosystems in the Deccan Plateau or certain coastal habitats have historically received less attention than forests. This allows for targeted conservation interventions.
• Development vs. Conservation Conflict: Many biogeographic zones face intense pressure from developmental activities, leading to policy dilemmas.
  • Deccan Plateau: Rich in mineral resources, leading to conflicts over mining in forested areas, habitat fragmentation due to road and rail networks, and pressure on water resources from agriculture.
  • North-East: This region’s push for infrastructure development (e.g., dams, highways under the Act East Policy) poses a significant threat to its fragile ecology and high endemism. Balancing developmental aspirations with the need to conserve a global biodiversity hotspot is a major governance challenge.

Drivers of Biodiversity Loss: An Analytical Perspective

• The Anthropocene Challenge: The causes of biodiversity loss—habitat destruction, overexploitation, pollution, and climate change—are overwhelmingly anthropogenic. This underscores the central theme of the Anthropocene epoch, where human activity has become the dominant influence on the environment and climate. The issue is not merely ecological but deeply intertwined with economic models, consumption patterns, and social equity.
• Interconnectedness of Causes (Synergistic Effects): The drivers of biodiversity loss do not act in isolation; they often have synergistic effects. For example, a forest fragmented by deforestation (habitat loss) is more vulnerable to the impacts of climate change (like droughts or intense fires). Similarly, pollution can weaken ecosystems, making them less resilient to climate change. This interconnectedness necessitates an integrated and holistic policy approach rather than addressing each threat in a silo.
• Policy and Implementation Gaps:
  • Forest Fires: The issue is less about the absence of policy and more about its implementation. While there are protocols for fire management, a lack of funding, technology, manpower, and community involvement often hampers effective action. The role of local communities and indigenous knowledge (as recognized under the Forest Rights Act, 2006) in fire prevention and management is often underutilized.
  • Pollution: Despite strong environmental laws (like the Water Act, 1974, and Air Act, 1981), weak monitoring and enforcement by State Pollution Control Boards, coupled with industrial non-compliance, remain major hurdles.
• Ethical Dimension (GS Paper IV): The continuous loss of biodiversity raises profound ethical questions. Does humanity have the right to drive other species to extinction for its own development? This relates to the concept of stewardship, where humans have a moral responsibility to protect the planet’s natural heritage for future generations. It also involves the principle of intrinsic value, which argues that species and ecosystems have a right to exist, independent of their utility to humans. Addressing biodiversity loss is thus not just a scientific or economic imperative, but a moral one.