Unit2 - Subjective Questions

Definition: An ecosystem is a self-sustaining structural and functional unit of the biosphere where living organisms (biotic factors) interact with each other and with their non-living physical environment (abiotic factors) to maintain a flow of energy and cycling of nutrients.

Structure of Ecosystem:

1. Abiotic Components (Non-living):

   • Physical factors: Temperature, light, rainfall, humidity, soil texture, and topography.
   • Chemical factors:
     • Inorganic substances: Carbon, nitrogen, oxygen, water, phosphorus, etc.
     • Organic substances: Proteins, carbohydrates, lipids, humic substances.

2. Biotic Components (Living):

   • Producers (Autotrophs): Organisms that synthesize their own food using sunlight (Photosynthesis) or chemicals (Chemosynthesis). Examples: Green plants, algae, phytoplankton.
   • Consumers (Heterotrophs): Organisms that depend on others for food.
     • Primary Consumers (Herbivores): Feed directly on producers (e.g., rabbits, insects).
     • Secondary Consumers (Carnivores): Feed on primary consumers (e.g., frogs, snakes).
     • Tertiary Consumers (Top Carnivores): Feed on secondary consumers (e.g., lions, eagles).
   • Decomposers (Saprotrophs): Microorganisms like bacteria and fungi that break down dead organic matter into simple inorganic substances, recycling them back into the soil.

The function of an ecosystem refers to the biological, geochemical, and physical processes that take place within it. The key functions include:

1. Energy Flow: The unidirectional flow of energy from the sun to producers and then to consumers. It follows the laws of thermodynamics.
2. Nutrient Cycling (Biogeochemical Cycles): The circulation of essential elements like Carbon, Nitrogen, Phosphorus, and Water between biotic and abiotic components.
3. Ecological Succession: The process by which the structure of a biological community evolves over time.
4. Homeostasis: The ability of an ecosystem to maintain a state of equilibrium or balance despite external stress.
5. Productivity: The rate of biomass production.
   • Primary Productivity: Gross and Net primary productivity by autotrophs.
   • Secondary Productivity: Rate of biomass assimilation by consumers.

Concept: An ecological pyramid is a graphical representation of the relationship between different organisms in an ecosystem at different trophic levels. The base represents producers, while the apex represents top consumers.

Types of Ecological Pyramids:

1. Pyramid of Number:

   • Represents the total number of individuals at each trophic level.
   • Upright: Grassland ecosystem (many grasses fewer herbivores few carnivores).
   • Inverted: Parasitic food chain (one tree many birds numerous parasites).

2. Pyramid of Biomass:

   • Represents the total dry weight (biomass) of organisms at each level.
   • Upright: Terrestrial ecosystems (Forests).
   • Inverted: Aquatic ecosystems (Biomass of phytoplankton is less than that of zooplankton and fishes).

3. Pyramid of Energy:

   • Represents the amount of energy transferred from one trophic level to the next.
   • Always Upright: Because energy is lost as heat at every step (accordance with the 2nd Law of Thermodynamics). Only about 10% of energy is passed to the next level.

Energy flow in an ecosystem is unidirectional (Sun Producers Consumers) and follows the 10% Law proposed by Raymond Lindeman (1942).

The 10% Law:

• During the transfer of energy from one trophic level to the next, only about 10% of the energy is stored as flesh/biomass and is available to the next trophic level.
• The remaining 90% is lost during respiration, movement, reproduction, and as heat.

Mathematical Representation:
If the sun provides $1,000,000$ Joules of sunlight:

1. Producers: Capture ~1% of sunlight $10,000$ J.
2. Primary Consumers: Receive 10% of producer energy $1,000$ J.
3. Secondary Consumers: Receive 10% of primary consumer energy $100$ J.
4. Tertiary Consumers: Receive 10% of secondary consumer energy $10$ J.

This loss of energy limits the number of trophic levels in a food chain (usually 4 to 5).

Definition: Ecological succession is the gradual and predictable change in the species composition of a given area over time, leading to the establishment of a stable climax community.

Differences:

Natural resources can be classified based on their availability and rate of regeneration:

1. Renewable Resources:

• Definition: Resources that can be replenished or regenerated naturally within a human lifespan or are inexhaustible.
• Characteristics: Sustainable if used wisely, usually eco-friendly.
• Examples:
  • Solar Energy: Inexhaustible source.
  • Wind Energy: Generated by air currents.
  • Forests & Biomass: Can regrow if not over-harvested.
  • Water: Replenished via the hydrological cycle.

2. Non-Renewable Resources:

• Definition: Resources that exist in fixed quantities and take millions of years to form. Once consumed, they cannot be replaced in a human timeframe.
• Characteristics: Exhaustible, usage often leads to pollution.
• Examples:
  • Fossil Fuels: Coal, Petroleum, Natural Gas.
  • Minerals: Iron, Copper, Aluminum.
  • Nuclear Fuels: Uranium, Thorium.

Problems with Forest Resources:

• Over-exploitation for timber and fuel.
• Conversion of forest land for agriculture and urbanization.
• Forest fires and mining activities.

Deforestation:

Causes:

1. Agriculture Expansion: Shifting cultivation (Jhum) and commercial farming.
2. Logging: Illegal and legal cutting for timber, paper, and plywood.
3. Mining: Removal of topsoil and vegetation for mineral extraction.
4. Infrastructure: Construction of dams (submerging forests), roads, and cities.

Effects:

1. Climate Change: Reduced carbon sequestration leads to higher levels and global warming.
2. Soil Erosion: Loss of tree roots loosens soil, leading to wash-off during rains.
3. Loss of Biodiversity: Habitat destruction forces extinction of flora and fauna.
4. Hydrological Cycle Disruption: Reduced transpiration leads to lower rainfall and drying of water sources.

Water resources face problems like scarcity, pollution, and conflict. Large dams, built for irrigation and hydropower, have significant environmental and social impacts.

Benefits of Dams:

• Generation of Hydroelectricity.
• Irrigation for agriculture.
• Flood control.

Problems/Impacts of Dams:

1. Displacement of People: Tribal and local communities are often forced to migrate due to the submergence of their land (e.g., Narmada Bachao Andolan).
2. Ecological Imbalance: Submergence of vast forests leads to loss of biodiversity.
3. Siltation: Accumulation of silt reduces the reservoir's capacity and lifespan.
4. Seismic Issues: The weight of massive reservoirs can induce seismicity (earthquakes).
5. Waterlogging and Salinity: Excessive irrigation in command areas leads to soil salinity, making land infertile.

Water Conflicts:
Water conflicts arise when demand exceeds supply, or when quality is compromised, leading to disputes between states, nations, or communities regarding the sharing and management of water resources.

Causes:

• Uneven distribution of rainfall.
• Construction of dams upstream reducing flow downstream.
• Pollution of shared water bodies.

Examples:

1. International:
   • Indus Water Treaty: Between India and Pakistan.
   • Nile River Dispute: Among Egypt, Ethiopia, and Sudan.
2. Inter-state (India):
   • Cauvery Water Dispute: Between Karnataka and Tamil Nadu.
   • Satluj-Yamuna Link Canal: Between Punjab and Haryana.
   • Krishna Water Dispute: Maharashtra, Karnataka, and Andhra Pradesh.

Land Degradation: The decline in land quality caused by human activities or natural processes, making it unfit for agriculture or habitation.

Types and Causes:

1. Soil Erosion:
   • Cause: Deforestation, overgrazing, wind, and running water remove the fertile topsoil.
2. Desertification:
   • Cause: Conversion of fertile land into desert due to prolonged drought, deforestation, and poor agricultural practices.
3. Salinization and Waterlogging:
   • Cause: Poor drainage and excessive irrigation accumulate salts on the surface (capillary action), rendering soil infertile.
4. Landslides:
   • Cause: Instability of slopes due to construction, mining, or deforestation in hilly areas.
5. Industrial Waste/Pollution:
   • Cause: Dumping of non-biodegradable toxic waste and mining debris affecting soil chemistry.

While governments make policies, conservation requires individual action. Small efforts by individuals can cumulatively lead to significant preservation of resources.

Practical Measures (The 3 R's: Reduce, Reuse, Recycle):

1. Energy Conservation:
   • Switch off lights/fans when not in use.
   • Use LED bulbs and energy-efficient appliances.
   • Use public transport or carpooling to save fuel.
2. Water Conservation:
   • Fix leaking taps immediately.
   • Practice rainwater harvesting.
   • Use buckets instead of hoses for washing cars.
3. Forest/Soil Conservation:
   • Go paperless where possible; print on both sides.
   • Plant trees (Kitchen gardening).
   • Avoid single-use plastics that degrade soil quality.
4. Food/Waste:
   • Don't waste food.
   • Compost organic kitchen waste instead of throwing it away.
   • Segregate dry and wet waste.

Renewable Energy (Solar, Wind, Hydro, Biomass):

• Advantages:
  • Environmentally friendly (low/zero carbon emissions).
  • Sustainable and inexhaustible.
  • Reduces dependence on imported fuels.
• Disadvantages:
  • High initial installation cost.
  • Intermittent availability (sun doesn't shine at night, wind varies).
  • Requires large land areas (solar farms).

Non-Renewable Energy (Coal, Oil, Natural Gas):

• Advantages:
  • High energy density (produces more power per unit).
  • Established infrastructure and technology.
  • Reliable and consistent power supply.
• Disadvantages:
  • Finite supply (will run out).
  • Releases Greenhouse Gases (, ) causing global warming.
  • Mining and extraction damage landscapes.

Growing Energy Needs:
Rapid industrialization, population explosion, urbanization, and technological advancements have caused an exponential surge in global energy demand. The current reliance on fossil fuels is unsustainable due to depletion and climate impact.

Importance of Alternate (Renewable) Energy Resources:

1. Sustainability: Sources like solar and wind are infinite.
2. Environmental Protection: Alternate energy drastically reduces pollution and Green House Gas emissions, mitigating climate change.
3. Energy Security: Diversifying energy sources prevents geopolitical crises related to oil prices/supply.
4. Rural Development: Decentralized power (e.g., solar lanterns, biogas) can reach remote villages without expensive grid infrastructure.
5. Economic Stability: Shifts investment from consuming resources to manufacturing technology (panels, turbines).

Xerosere is a succession that begins in dry conditions, typically on a bare rock. The stages are:

1. Crustose Lichen Stage: Pioneer species (e.g., Rhizocarpon) colonize the rock. They secrete acids that corrode rock, forming a thin layer of soil.
2. Foliose Lichen Stage: Leafy lichens (e.g., Parmelia) appear. They retain more moisture and accumulate more dust/soil.
3. Moss Stage: Mosses (e.g., Polytrichum) grow, forming mats that hold significant soil and moisture, shading out lichens.
4. Herb Stage: Shallow-rooted annual grasses and herbs replace mosses as soil depth increases.
5. Shrub Stage: Larger woody shrubs invade, shading herbs and adding humus to the soil.
6. Climax Community (Forest): Trees (mesophytes) establish. The community becomes stable and self-perpetuating, determined by the local climate.

Equitable Use:
Equitable use refers to the fair distribution of natural resources among all sections of society (rich and poor) and between developed and developing nations. Currently, developed nations (Global North) consume a disproportionately high share of resources compared to developing nations (Global South).

Relation to Sustainable Lifestyles:

• Gap Reduction: Sustainability cannot be achieved if a minority consumes the majority of resources. Equitable use ensures basic needs for all are met without over-exploitation.
• Future Generations: It implies leaving enough resources for future generations (Inter-generational equity).
• Lifestyle Change: It requires the wealthy to shift from consumerism to conservation, allowing the under-privileged to access resources for development. This balance is crucial for global environmental stability.

Ecosystems are broadly classified into Terrestrial (land-based) and Aquatic (water-based).

1. Terrestrial Ecosystems:

• Forest Ecosystem: Dominated by trees. High biodiversity. Types: Tropical Rainforests, Temperate Deciduous, Coniferous (Taiga).
• Grassland Ecosystem: Dominated by grasses rather than large shrubs/trees. Moderate rainfall. Examples: Savannas, Prairies.
• Desert Ecosystem: Scanty rainfall ( cm/year), extreme temperatures. Flora/fauna adapted to conserve water (e.g., Cactus, Camels).

2. Aquatic Ecosystems:

• Freshwater: Low salt content.
  • Lentic: Standing water (Ponds, Lakes).
  • Lotic: Running water (Rivers, Streams).
• Marine: High salt content. Includes Oceans, Coral Reefs, and Estuaries (where river meets sea). They cover roughly 71% of Earth's surface.

To combat land degradation and soil erosion, the following remedial measures are used:

1. Afforestation/Reforestation: Planting trees binds the soil with roots and acts as windbreaks.
2. Terrace Farming: Creating steps on hilly slopes reduces the speed of water runoff and soil wash-off.
3. Contour Plowing: Plowing along the contour lines of a slope rather than up and down creates natural barriers for water.
4. Crop Rotation: Alternating crops restores soil nutrients naturally, reducing the need for chemical fertilizers that degrade soil structure.
5. Mulching: Covering bare soil with organic matter (straw/leaves) retains moisture and prevents wind erosion.
6. Construction of Check Dams: Small barriers in streams reduce water velocity and trap silt.

A food web is a network of interconnected food chains. Its significance includes:

1. Stability: The complexity of a food web ensures ecosystem stability. If one species' population drops, predators have alternative food sources, preventing the collapse of the system.
2. Check on Overpopulation: It maintains a balance in the population of different species. For example, if deer increase, the predator population (tigers) will increase due to food availability, eventually controlling the deer population.
3. Energy Flow Channels: It provides multiple pathways for energy flow and nutrient cycling.
4. Resilience: Diverse food webs make ecosystems more resilient to disturbances (e.g., disease outbreaks affecting one species won't wipe out the whole system).

Mining is the extraction of valuable minerals or other geological materials from the earth. While economically important, it causes severe environmental damage:

1. Land Degradation: Open-cast mining leaves huge scars and pits, rendering land useless (overburden heaps).
2. Deforestation: Mining often requires clearing large tracts of forest cover.
3. Air Pollution: Dust and particulate matter from blasting and transport cause respiratory diseases (e.g., Silicosis) and coat nearby vegetation.
4. Water Pollution: Acid Mine Drainage (AMD) occurs when sulfide minerals are exposed to air and water, creating sulfuric acid that contaminates groundwater and rivers.
5. Loss of Biodiversity: Noise and habitat destruction drive away wildlife.
6. Subsidence: Underground mining can lead to the sudden collapse of land surface.