Natural and Man-Made Ecosystems
Ecosystems are functional units where living organisms interact with the physical environment, enabling energy flow and nutrient cycling. They may develop naturally over long ecological timescales or be created and managed by humans for specific needs. Understanding both natural and man-made ecosystems helps assess ecological balance, sustainability, and human impacts on biodiversity.
Natural Ecosystems
Natural ecosystems arise through ecological succession without deliberate human intervention. They exhibit high biodiversity, complex food webs, and self-regulating mechanisms that maintain stability and resilience.
Forest Ecosystems
Forests like Western Ghats or Himalayan forests support rich biodiversity, multi-layered vegetation, climate regulation, and strong predator-prey balance.
Grassland Ecosystems
Grasslands such as Banni support herbivores like blackbuck and are shaped by grazing and fire, maintaining open landscapes.
Desert Ecosystems
Deserts like the Thar have low rainfall, sparse vegetation, and organisms with adaptations such as water conservation and nocturnal behavior.
Aquatic Ecosystems
Rivers, lakes, estuaries, and oceans like Ganga basin and Chilika support diverse aquatic species and regulate hydrological cycles.
Key Features of Natural Ecosystems
- High biodiversity and richness
- Complex food webs and interactions
- Self-regulation through ecological feedbacks
- High resilience to natural disturbances
- Minimal external energy input
Man-Made (Artificial) Ecosystems
Man-made ecosystems are designed, modified, or maintained by humans to obtain goods, services, or aesthetic benefits. They have controlled conditions, relatively lower biodiversity, and depend on continuous human management.
Agricultural Ecosystems
Farms and orchards focus on monoculture or mixed cropping, with high inputs like irrigation and fertilizers for productivity.
Urban Ecosystems
Cities with built-up areas, parks, and lakes support limited wildlife such as pigeons, bats, and ornamental plants.
Industrial and Mining Ecosystems
Industrial zones alter landforms drastically; reclamation attempts include grassing and plantation forestry.
Aquaculture and Reservoir Ecosystems
Fish farms, dams, and reservoirs support controlled aquatic life but disrupt natural flow and species migration.
Key Features of Man-Made Ecosystems
- Low biodiversity under human control
- High productivity for human needs
- High external energy inputs
- Low ecological stability without management
- Simplified food chains
Terrestrial Ecosystems: An Overview
Terrestrial ecosystems occur on land and are shaped by interactions among climate, soil, and topography. These factors influence species composition, productivity, and biodiversity. As dynamic systems, they regulate climate, support food webs, and sustain life across the planet.
Overview
Terrestrial ecosystems are land-based habitats that vary widely—from forests and grasslands to deserts and tundra. Their structure and functioning depend on climate, soil, topography, and nutrient cycling, which collectively shape global biodiversity patterns.
1. Extent and Global Distribution
Terrestrial ecosystems cover about 28–30% of Earth’s surface. Forests occupy nearly 31% of land area. Other major systems include grasslands, deserts, tundra, and savannas, each with distinct climate and vegetation patterns.
2. Key Environmental Determinants
Temperature influences metabolic rates; precipitation controls water availability; seasonality affects life cycles and vegetation turnover. These factors create biomes ranging from tropical forests to arctic tundra.
3. Productivity Patterns Across Ecosystems
Productivity is highest in tropical rainforests (~2200 g/m²/yr), lowest in deserts (~90 g/m²/yr), and moderate in temperate forests and grasslands, reflecting climate and soil conditions.
4. Biodiversity Variations
Tropical rainforests host over half of all terrestrial species. Deserts and tundra contain sparse but highly specialized species adapted to extreme conditions like aridity or freezing temperatures.
5. Ecological Roles and Services
Terrestrial ecosystems support food webs, regulate climate through carbon storage, maintain soil fertility, and provide habitats for diverse fauna, making them crucial for global stability.
Forest Types in India
India’s forests reflect exceptional ecological diversity shaped by climate, rainfall, altitude, and soil. These varied forest types support unique flora, fauna, ecosystem services, and cultural landscapes. The major forest types include tropical, temperate, alpine, and coastal categories—each vital for biodiversity conservation and climate regulation.
1. Tropical Evergreen Forests
Found in regions with over 200 cm rainfall—Western Ghats, NE India, Andaman–Nicobar. Evergreen, dense, multi-layered forests with species like ebony, rosewood, orchids; fauna includes lion-tailed macaque and Malabar civet.
2. Tropical Deciduous Forests
India’s largest forest category, found where rainfall is 100–200 cm. Trees shed leaves seasonally; species include sal, teak, bamboo. Wildlife includes tigers, sloth bears, elephants, and gaur.
3. Tropical Thorn Forests
Occur in arid areas (rainfall < 70 cm) of Rajasthan, Haryana, Gujarat. Vegetation includes acacia, euphorbia, babool. Wildlife includes blackbuck, chinkara, desert fox.
4. Montane Forests
Found in Himalayan and south Indian hills. Composition varies with altitude—from subtropical pine to temperate conifers. Hosts red panda, Himalayan black bear, pheasants.
5. Mangrove Forests
Found in tidal coasts—Sundarbans, Bhitarkanika, Gulf of Kachchh. Species like Rhizophora and Avicennia have stilt/pneumatophore roots. Support Bengal tiger, crocodiles, rich fisheries.
6. Littoral & Swamp Forests
Occur along coasts, deltas, estuaries, marshes. Include beach forests and freshwater swamp forests. Support wetland biodiversity, flood control, and nutrient cycling.
7. Montane Temperate Forests
Occur at 1800–3000 m in the Himalayas. Dominated by oaks, rhododendrons, conifers. Home to Himalayan tahr, monal, mosses, and lichens.
8. Sub-Alpine & Alpine Forests
Above 3000 m; sub-alpine forests give way to alpine meadows. Vegetation includes junipers, firs, dwarf shrubs. Supports snow leopard, blue sheep, marmots.
Grassland and Desert Ecosystems
Grassland and desert ecosystems represent major terrestrial biomes shaped by climate, rainfall, soil, and vegetation. Both support specialized flora and fauna adapted to resource scarcity and climatic extremes, contributing to ecological balance and biodiversity.
1. Definition and Distribution
Grasslands: Dominated by grasses, receiving 25–75 cm rainfall; found in Deccan Plateau, Terai, Rajasthan, MP.
Deserts: Very low rainfall (<25 cm), sparse vegetation; mainly Thar Desert in Rajasthan and Gujarat.
2. Climate Characteristics
Grasslands: Seasonal rainfall, dry summers, fires, hot summers & cool winters.
Deserts: Extreme heat (45°C+), cold nights, unpredictable short rainfall bursts.
3. Soil Features
Grasslands: Nutrient-rich, high organic matter, black/alluvial soils.
Deserts: Sandy, saline, low humus, porous soils with poor water retention.
4. Vegetation Structure
Grasslands: Grasses, herbs, scattered shrubs; fires prevent tree growth.
Deserts: Acacias, cacti, succulents, deep-rooted shrubs with spines & waxy leaves.
5. Faunal Diversity
Grasslands: Blackbuck, chital, nilgai, bustard, wolves, jackals, raptors.
Deserts: Chinkara, desert fox, camels, monitor lizards, spiny-tailed lizard; many nocturnal.
6. Ecological Roles
Grasslands: Support nutrient cycling, carbon storage, groundwater recharge, grazing fauna.
Deserts: Regulate heat balance, sustain xeric biodiversity, create mineral-rich niches.
7. Human–Ecosystem Interactions
Grasslands: Pastoralism, fodder, agriculture; many degraded by overgrazing & land conversion.
Deserts: Pastoralism, mining, salt extraction; canal irrigation transforms landscapes.
8. Threats
Grasslands: Encroachment, urbanization, afforestation with exotics, fragmentation.
Deserts: Desertification, mining, tourism pressure, invasive species, droughts.
9. Conservation Efforts
Grasslands: Banni (Gujarat), Rollapadu (AP), Velavadar NP protect blackbuck & bustards.
Deserts: Desert NP safeguards Thar biodiversity; sustainable water/land use promoted.
Major Global Biomes
Large ecological regions shaped by climate, vegetation, and faunaBiomes are large ecological regions distinguished by climate, vegetation, and animal life. They reflect global patterns of temperature, precipitation, and seasonality, shaping the world’s ecosystems. Understanding biomes provides insights into biodiversity distribution, ecological functioning, and climate-change impacts.
Tropical Rainforest Biome
Near the equator with warm year-round temperatures and rainfall >200 cm. Dense evergreen canopies host the highest biodiversity and major carbon sinks.
Tropical Deciduous (Seasonal) Forest Biome
Monsoon-influenced forests with distinct wet and dry seasons; trees shed leaves in dry months to conserve water.
Temperate Forest Biome
Regions with moderate rainfall and clear seasons — deciduous and temperate evergreen forests supporting diverse mammals and migratory birds.
Taiga (Boreal Forest) Biome
Vast coniferous belt across Canada, Russia, Scandinavia — long cold winters, short summers, dominated by spruce, fir, and pine.
Temperate Grassland Biome
Prairies and steppes with rainfall too low for forests; dominated by grasses and grazing mammals — soils are fertile and used heavily for agriculture.
Savanna (Tropical Grassland) Biome
Tropical grasslands with scattered trees shaped by wet/dry seasons and fires; support iconic large herbivores and predators.
Desert Biome
Arid regions with <25 cm rainfall, extreme temperatures, sparse vegetation (cacti, succulents), and specially adapted fauna.
Tundra Biome
Arctic and high-mountain regions with permafrost, low vegetation (mosses, lichens, dwarf shrubs), and short growing seasons.
Alpine Biome
High-altitude regions across major mountain ranges; vegetation is low-growing and adapted to cold, wind, and low oxygen.
Mediterranean Biome
Hot, dry summers and mild, wet winters with sclerophyllous shrubs (chaparral, maquis, fynbos) and high plant endemism.
Aquatic Ecosystems – Freshwater & Marine
Aquatic ecosystems cover nearly three-quarters of Earth’s surface and support immense biodiversity, climate regulation, nutrient cycling, and human livelihoods. They are broadly classified into freshwater ecosystems and marine ecosystems, shaped by salinity, depth, temperature, and nutrient availability.
1. Freshwater Ecosystems
Freshwater ecosystems contain low salinity (<0.5 ppt) and support high productivity. They are vital for drinking water, irrigation, fisheries, and nutrient transport across landscapes.
1.1 Rivers and Streams (Lotic Systems)
Flowing water, high oxygen, and dynamic nutrient movement. Biodiversity changes from headwaters to floodplains.
Example: Ganga River supports dolphins, gharials, and migratory fish.
1.2 Lakes and Ponds (Lentic Systems)
Standing water with stratified thermal layers and well-defined ecological zones.
Example: Dal Lake shows eutrophication, triggering restoration efforts.
1.3 Wetlands
Marshes, swamps, and peatlands act as natural purifiers, carbon sinks, and flood buffers.
Example: Chilika Lake hosts Irrawaddy dolphins.
1.4 Groundwater and Springs
Aquifers and subterranean streams maintain river baseflow and host cave fauna.
Example: Meghalaya caves support diverse troglobitic species.
1.5 Biodiversity in Freshwater
Supports amphibians, plants, insects, molluscs, and fish adapted to low salinity.
Threats: Eutrophication, invasives, sand mining, hydrological shifts.
2. Marine Ecosystems
High salinity (35 ppt) systems including oceans, reefs, estuaries, and coasts. They regulate global climate and carbon cycles.
2.1 Open Ocean (Pelagic Zone)
Supports plankton, fish, mammals; productivity depends on upwelling.
Example: Indian Ocean tuna fisheries.
2.2 Deep Sea (Abyssal Zone)
Cold, dark, high-pressure zones with chemosynthetic life.
Example: Andaman trench deep-sea organisms.
2.3 Coastal Waters
Bays, lagoons, seagrass meadows—nurseries for fish and invertebrates.
Example: Gulf of Mannar Biosphere Reserve.
2.4 Coral Reefs
Highly productive, species-rich, and climate-sensitive ecosystems.
Example: Lakshadweep bleaching events.
2.5 Estuaries and Mangroves
Blend freshwater and marine conditions; high productivity and storm protection.
Example: Sundarbans mangroves.
Mangroves, Estuaries & Coral Reefs – India’s Status
India’s coastal ecosystems—mangroves, estuaries, and coral reefs—are among the world’s most productive habitats. They protect coastlines, support fisheries, and host unique biodiversity, yet face increasing threats from pollution, climate change, and habitat loss.
Mangroves in India
Salt-tolerant intertidal forests stabilizing coasts, reducing cyclones, storing blue carbon.
Major Mangrove Regions
Sundarbans: Largest mangrove forest; Bengal tiger habitat.
Bhitarakanika: Dense Avicennia; saltwater crocodiles.
Gulf of Kachchh: Expanding due to restoration.
Godavari–Krishna Delta: Nursery grounds.
Andaman & Nicobar: High species diversity.
Threats
Pollution, wetland conversion, salinity changes, cyclones.
Conservation Measures
CRZ rules, afforestation, JFM, NCSCM coastal research.
Estuaries in India
Nutrient-rich river–sea transition zones supporting high productivity and fisheries.
Major Estuarine Systems
GBM Estuary: Influences Bay fisheries.
Mahanadi & Brahmani: Linked with Bhitarakanika.
Krishna–Godavari: High plankton.
Narmada & Tapi: Unique sediment pattern.
Mandovi–Zuari: Tourism & navigation.
Threats
Pollution, dredging, salinity intrusion, dams.
Conservation Efforts
Wetland restoration, ICZM projects, river cleanup missions.
Coral Reefs in India
Highly diverse marine ecosystems protecting islands and supporting fisheries.
Key Coral Regions
Gulf of Mannar: 117 species.
Lakshadweep: Atoll reefs.
Andaman & Nicobar: Largest reef cover.
Gulf of Kachchh: Restoration success.
Current Trends
Mass bleaching, diseases, invasive species, but active restoration.
Conservation Measures
MPAs, coral rehab, monitoring, ecotourism regulations.
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