Life on Earth

The One Thing

Life on Earth depends on interconnected biomes, forests, wildlife and human communities. Effective conservation therefore requires habitat protection, scientific management, legal regulation, responsible ecotourism and the rights and participation of forest dwellers.

Chronology

Who and What

• Ecosystem: A functional unit in which living organisms interact with one another and with non-living elements such as air, water, soil and sunlight.
• Biome: A large natural region with a particular climate, vegetation and animal life, such as deserts, grasslands, tropical forests or tundra.
• Biosphere: The narrow zone of Earth where life exists, including parts of the land, water and atmosphere.
• Biodiversity: The variety of living organisms, including different species, genes and ecosystems, found in a region or on Earth.
• Natural vegetation: Plants that grow without direct human interference and are mainly influenced by climate, soil, relief and water.
• Wildlife: Undomesticated animals, birds, insects and other organisms living in their natural habitats.
• Biosphere reserve: A large protected area created to conserve biodiversity, support research and promote sustainable development.
• Core zone: The most strictly protected part of a biosphere reserve, where human disturbance is kept to a minimum.
• Buffer zone: The area surrounding the core zone, where research, education and limited tourism may be permitted.
• Transition zone: The outer part of a biosphere reserve, where people live and sustainable activities such as farming, forestry and responsible tourism may occur.
• National park: A protected area established mainly to conserve ecosystems, plants and animals, with restrictions on human activities.
• Wildlife sanctuary: A protected area created mainly to protect wild animals and their habitats, although some regulated human activities may be permitted.
• Forest conservation: The protection, careful management and restoration of forests so that ecological, economic and social needs can continue in the future.
• Afforestation: Planting trees on land that has not recently been covered by forests.
• Reforestation: Restoring forest cover by planting trees in areas where forests were destroyed or cleared.
• Deforestation: The large-scale removal of forests for farming, settlements, industries, roads, mining or other uses.
• Ecotourism: Responsible travel to natural areas that minimises environmental damage, supports conservation and benefits local communities.
• Forest dwellers: People and communities who live in or near forests and depend on forest resources for their livelihood, culture and daily needs.
• Sustainable development: Development that meets present needs without reducing the ability of future generations to meet their needs.
• Endangered species: A species whose population has fallen so greatly that it faces a high risk of extinction.
• Endemic species: A species naturally found only in a particular geographical area.
• Food chain: A sequence showing how energy and nutrients pass from producers to consumers and decomposers.
• Tropical evergreen forests: Forests found in areas with high temperature and heavy rainfall throughout the year. They are dense, multi-layered and rich in biodiversity.
• Tropical deciduous forests: Forests whose trees shed leaves during the dry season to reduce water loss. They are among the most widespread forests in India.
• Thorn forests and scrub: Vegetation found in regions with low rainfall. Plants commonly have thorns, small leaves or deep roots that conserve water.
• Mountain vegetation: Vegetation that changes with altitude because temperature decreases as height increases. It may pass from forests to grasslands and finally to alpine plants and snow.
• Mangrove forests: Forests growing in tidal coastal areas and river deltas. Their salt-tolerant plants protect coasts, reduce erosion and provide breeding grounds for aquatic life.
• Project Tiger: A programme launched in India in 1973 to protect tigers and their habitats.
• Wildlife Protection Act: Indian legislation enacted in 1972 to provide legal protection to wild animals, birds and plants.
• Forest Conservation Act: Indian legislation enacted in 1980 to control the diversion of forest land for non-forest purposes.
• National Forest Policy of 1988: A policy emphasising ecological stability, environmental protection, restoration of degraded forests and local-community involvement.
• Forest Rights Act, 2006: Legislation recognising certain individual and community rights of forest-dwelling Scheduled Tribes and other traditional forest dwellers, subject to its provisions.
• Nilgiri Biosphere Reserve: India’s first biosphere reserve, established in 1986. Other important Indian biosphere reserves include Nanda Devi, Gulf of Mannar, Sundarbans, Simlipal, Great Nicobar, Pachmarhi, Kanha, Agasthyamalai and Kachchh.

Causes and Consequences

• Climate and physical conditions shape biomes. Temperature, rainfall, soil, relief, water availability and sunlight determine the distribution of ecosystems and natural vegetation. Major terrestrial biomes include tropical forests, temperate forests, grasslands, deserts, Mediterranean vegetation and tundra; aquatic biomes include freshwater and marine ecosystems.

• Organisms are adapted to their environments. Tropical evergreen forests remain dense because rainfall is heavy throughout the year, whereas tropical deciduous forests shed leaves during the dry season to reduce water loss. Thorn forests and scrub conserve water through thorns, small leaves and deep roots. Mountain vegetation changes with altitude because temperature decreases as height increases, while mangroves tolerate salt and tidal conditions.

• Plants support the wider ecosystem. Plants are primary producers because they make food through photosynthesis:

carbon dioxide + water + sunlight and chlorophyll → glucose + oxygen

Energy and nutrients then pass through food chains, for example:

plants → herbivores → carnivores → decomposers

• Forests provide essential ecosystem services. They regulate temperature and rainfall, absorb carbon dioxide, release oxygen, prevent soil erosion, recharge groundwater, provide habitats and support livelihoods. Consequently, forest destruction can cause soil erosion, water scarcity, climate risks, biodiversity loss and the loss of livelihoods.

• Wildlife declines when habitats and ecological relationships are disrupted. Major causes include habitat destruction and fragmentation, hunting and poaching, pollution, forest fires, invasive species, climate change and illegal trade. Habitat conservation is generally more effective than protecting only individual animals because species depend on complete food webs and ecological relationships.

• Protected areas developed through legislation and conservation programmes. Hailey National Park, established in 1936 and now known as Jim Corbett National Park, was India’s first national park. The Wildlife Protection Act of 1972, Project Tiger in 1973 and the Forest Conservation Act of 1980 strengthened legal and institutional protection.

• Different protected areas permit different levels of human activity. National parks generally impose stricter protection than wildlife sanctuaries. Biosphere reserves cover larger areas and may include settlements and several types of protected areas. Their core, buffer and transition zones combine strict conservation with research, education and sustainable community-based activities.

• Biosphere reserves connect conservation with sustainable development. The Nilgiri Biosphere Reserve, established in 1986, was India’s first biosphere reserve. Other important examples are Nanda Devi, Gulf of Mannar, Sundarbans, Simlipal, Great Nicobar, Pachmarhi, Kanha, Agasthyamalai and Kachchh.

• Uncontrolled exploitation creates short-term economic gains but long-term environmental and social costs. Sustainable use of forest resources is preferable because it protects biodiversity while supporting present and future generations. Afforestation and reforestation can increase or restore forest cover, whereas deforestation removes forests for farming, settlements, industries, roads, mining and other uses.

• Forest dwellers depend on forests in multiple ways. They obtain shelter, food, medicine, cultural resources and livelihoods, including non-timber forest products such as fruits, honey, bamboo, medicinal plants, leaves, gums and resins. The Forest Rights Act, 2006 recognises certain individual and community rights of forest-dwelling Scheduled Tribes and other traditional forest dwellers, subject to its provisions.

• Ecotourism can support conservation only under strict conditions. Visitor numbers must be controlled, littering and pollution prevented, disturbance to animals avoided and resource use reduced. Benefits must reach conservation programmes and local residents. Without these safeguards, tourism may damage the ecosystems it claims to support.

• Conservation is most effective when it combines several approaches. Habitat protection, scientific management, strict action against illegal activities, environmental education and the participation of local communities must operate together. This approach also reflects the National Forest Policy of 1988, which emphasised ecological stability, restoration of degraded forests and local involvement.

What Gets Asked

• How do climate, soil, relief, water availability and sunlight shape the distribution of biomes and the adaptations of organisms within them?
• Compare tropical evergreen forests, tropical deciduous forests, thorn forests and scrub, mountain vegetation and mangrove forests.
• Explain how forests support ecological balance, including photosynthesis, food chains, oxygen production, carbon dioxide absorption, soil protection and groundwater recharge.
• Compare national parks, wildlife sanctuaries and biosphere reserves, including the functions of core, buffer and transition zones.
• Evaluate the causes of wildlife decline and explain why habitat conservation is generally more effective than protecting individual animals alone.
• Assess how ecotourism, sustainable development and the rights and participation of forest dwellers can be combined with biodiversity conservation.