Unit 2: Natural resources and ecosystem - Subjective Questions

Natural resources are materials, organisms, and components obtained from nature that support life and satisfy human needs.

Examples include:

• Air, water, soil, and land
• Forests and wildlife
• Minerals and fossil fuels
• Solar, wind, and hydropower

Importance of natural resources:

• Life support: Air, water, soil, and sunlight sustain living organisms.
• Economic development: Agriculture, industry, transport, and energy production depend on natural resources.
• Ecological balance: Forests, wetlands, and oceans regulate climate and nutrient cycles.
• Livelihoods: Farming, fishing, forestry, and mining provide employment.
• Cultural value: Many communities have spiritual and cultural relationships with natural landscapes.

Because natural resources are limited or vulnerable to degradation, they must be used efficiently and conserved for future generations.

Renewable resources are replenished naturally within a relatively short period, whereas non-renewable resources are available in limited quantities and take geological periods to form.

Some renewable resources, such as forests and groundwater, can become depleted when their rate of consumption exceeds their rate of regeneration. Therefore, renewability does not mean unlimited availability.

Land is used for agriculture, forestry, settlements, industries, transport networks, mining, recreation, and wildlife habitats.

Causes of land degradation:

• Deforestation and removal of vegetation
• Overgrazing by livestock
• Excessive use of fertilizers and pesticides
• Mining and quarrying
• Urbanization and unplanned construction
• Improper irrigation leading to salinity and waterlogging
• Soil erosion by wind and water

Consequences:

• Decline in soil fertility and crop productivity
• Desertification and loss of vegetation
• Increased floods and sedimentation of rivers
• Destruction and fragmentation of habitats
• Loss of biodiversity
• Food insecurity and displacement of communities

Land degradation can be reduced through afforestation, contour farming, controlled grazing, reclamation of mined land, sustainable agriculture, and scientific land-use planning.

Major water-resource problems:

• Scarcity: Population growth, urbanization, and agriculture increase demand.
• Groundwater depletion: Excessive pumping lowers the water table.
• Pollution: Sewage, industrial effluents, fertilizers, pesticides, and plastics contaminate water.
• Unequal distribution: Water availability differs across regions and seasons.
• Floods and droughts: Climate variability and poor watershed management intensify extremes.
• Conflicts: Competing demands can create disputes between users and regions.

Remedial measures:

• Harvest and store rainwater.
• Restore wetlands, ponds, and watersheds.
• Adopt drip and sprinkler irrigation.
• Treat sewage and industrial wastewater before discharge.
• Reuse treated wastewater where appropriate.
• Regulate groundwater extraction and recharge aquifers.
• Protect riverbanks and catchment vegetation.
• Promote water-efficient appliances and responsible consumption.

Integrated water-resource management is necessary to balance ecological requirements with domestic, agricultural, and industrial needs.

Ecological importance of forests:

• Absorb carbon dioxide and help regulate climate.
• Release oxygen and improve air quality.
• Protect soil from erosion.
• Regulate the water cycle and reduce floods.
• Provide habitats for numerous species.
• Maintain nutrient cycles and ecological stability.

Economic and social importance:

• Supply timber, fuelwood, fodder, fibers, medicines, fruits, gums, and resins.
• Support forest-based industries and employment.
• Sustain the livelihoods and cultures of forest-dependent communities.
• Provide recreation and ecotourism opportunities.

Causes of deforestation:

• Expansion of agriculture and plantations
• Logging and fuelwood collection
• Mining, dams, roads, and industries
• Urban expansion and infrastructure development
• Overgrazing and forest fires
• Illegal encroachment

Sustainable forestry, afforestation, community participation, protected areas, and reduced dependence on fuelwood can help conserve forest resources.

Conventional energy resources are traditionally and widely used sources, such as coal, petroleum, natural gas, large hydropower, and fuelwood. Non-conventional energy resources include solar, wind, tidal, geothermal, biogas, and other emerging renewable sources.

A cleaner-energy transition is necessary to reduce greenhouse-gas emissions, air pollution, ecological damage from extraction, and dependence on finite fuels. The transition requires energy storage, efficient grids, responsible siting, improved technology, and energy conservation.

Sustainable management of natural resources means using and protecting resources in a way that meets present needs without reducing the ability of future generations to meet their needs.

Major principles:

• Intergenerational equity: Preserve adequate resources for future generations.
• Intragenerational equity: Ensure fair access among present communities.
• Carrying capacity: Keep resource use within the regenerative capacity of ecosystems.
• Precautionary principle: Prevent serious environmental damage even when scientific certainty is incomplete.
• Polluter-pays principle: Make those causing pollution bear the cost of control and restoration.
• Efficiency: Reduce waste and obtain greater benefit from fewer resources.
• Biodiversity conservation: Protect species, habitats, and ecological processes.
• Public participation: Include local communities in planning and decision-making.

Sustainable management integrates environmental protection, economic viability, and social justice.

Individuals contribute to conservation through everyday choices and participation in community action.

Land conservation:

• Segregate waste and compost biodegradable material.
• Avoid littering and unnecessary use of disposable products.
• Support soil conservation and tree-planting activities.

Water conservation:

• Repair leaking taps and pipes.
• Use water-efficient fixtures and avoid excessive consumption.
• Harvest rainwater and reuse suitable household water.
• Prevent oils, chemicals, and medicines from entering drains.

Forest conservation:

• Reduce paper and wood consumption.
• Reuse and recycle paper products.
• Choose responsibly sourced forest products.
• Participate in afforestation and habitat-protection programs.

Energy conservation:

• Switch off unused devices and use efficient appliances.
• Prefer walking, cycling, public transport, or shared travel.
• Use daylight, natural ventilation, and renewable energy where possible.

Individuals can also spread awareness, support environmental laws, and hold institutions accountable for resource use.

An ecosystem is a functional unit in which a community of organisms interacts with its physical environment through energy flow and nutrient cycling.

Abiotic components:

• Climatic factors: Light, temperature, rainfall, humidity, and wind
• Inorganic substances: Water, oxygen, carbon dioxide, nitrogen, and minerals
• Organic substances: Carbohydrates, proteins, lipids, and humus
• Physical factors: Soil, topography, salinity, and pH

Biotic components:

• Producers: Green plants and algae that manufacture food through photosynthesis
• Consumers: Herbivores, carnivores, and omnivores that obtain energy by feeding on other organisms
• Decomposers: Bacteria and fungi that break down dead matter and release nutrients
• Detritivores: Organisms such as earthworms that fragment dead organic material

The continuous interaction of these components maintains ecosystem structure and function.

The major functions of an ecosystem are:

• Productivity: Producers convert solar energy into chemical energy. Gross primary productivity is the total energy fixed, while net primary productivity is the energy remaining after plant respiration:
  
  where is net primary productivity, is gross primary productivity, and is respiratory loss.
• Energy flow: Energy moves from producers to consumers and decomposers through feeding relationships.
• Decomposition: Dead organic matter is broken down through fragmentation, leaching, catabolism, humification, and mineralization.
• Nutrient cycling: Elements such as carbon, nitrogen, phosphorus, and water circulate between organisms and the physical environment.
• Ecological regulation: Interactions among organisms help regulate populations and maintain dynamic balance.
• Habitat provision: Ecosystems provide food, shelter, breeding sites, and ecological niches.

Together, these processes maintain ecosystem stability and biological productivity.

A forest ecosystem is dominated by trees and contains diverse organisms arranged in distinct vertical layers.

Abiotic components:

• Sunlight, rainfall, temperature, air, soil, water, and minerals
• Organic matter and humus on the forest floor

Biotic structure:

• Producers: Trees, shrubs, herbs, grasses, mosses, and climbers
• Primary consumers: Insects, deer, rodents, and other herbivores
• Secondary consumers: Foxes, snakes, birds, and small carnivores
• Top consumers: Tigers, leopards, eagles, and other predators
• Decomposers: Fungi, bacteria, termites, and detritivores

Vertical stratification:

• Emergent layer
• Canopy
• Understory
• Shrub and herb layers
• Forest floor

Forest ecosystems generally show high biomass, complex food webs, efficient nutrient cycling, and significant biodiversity. They also regulate climate, conserve soil, and influence the water cycle.

Grasslands are maintained by seasonal drought, grazing, and fire. Deserts have sparse vegetation and organisms with strong water-saving adaptations. Aquatic ecosystems include freshwater and marine environments, whose organisms are influenced by salinity, temperature, light penetration, currents, and dissolved nutrients.

Energy enters most ecosystems as sunlight. Producers capture a small portion of solar energy through photosynthesis and store it as chemical energy. This energy then moves through trophic levels:

Sun producers herbivores carnivores decomposers

Energy flow is unidirectional because energy lost as heat during respiration cannot be recycled back to the Sun or the previous trophic level.

According to Lindeman's 10 percent law, approximately 10 percent of the energy at one trophic level is transferred to the next trophic level. If producers store , the approximate transfer is:

• Primary consumers:
• Secondary consumers:
• Tertiary consumers:

The remaining energy is used in metabolism, movement, growth, and reproduction or is lost as heat and waste. This low transfer efficiency limits the length of food chains and explains why organisms at higher trophic levels are fewer.

A food chain is a linear sequence showing how food, energy, and nutrients pass from one organism to another through feeding.

Grazing food chain:

• Begins with living green plants or phytoplankton.
• Energy passes from producers to herbivores and then to carnivores.
• Example: Grass grasshopper frog snake eagle
• It is common in grasslands and many aquatic ecosystems.

Detritus food chain:

• Begins with dead organic matter, called detritus.
• Detritivores and decomposers use the detritus and are then consumed by predators.
• Example: Dead leaves earthworm bird hawk
• It is especially important in forests, wetlands, and the deep ocean.

Both chains are interconnected. The grazing chain uses living plant biomass, while the detritus chain recycles dead matter and returns nutrients to the environment.

A food web is a network of interconnected food chains showing the multiple feeding relationships within an ecosystem. An organism may consume several species and may itself be eaten by several predators.

Importance of food webs:

• They provide alternative food sources when one species declines.
• They distribute energy through multiple ecological pathways.
• They help regulate populations through predator-prey interactions.
• They connect grazing and detritus pathways.
• They reveal the ecological importance of omnivores and species occupying more than one trophic level.

Food webs usually increase stability because consumers can shift to alternative prey when a particular food source becomes scarce. However, stability depends on the strength and diversity of connections. The loss of a keystone species or major producer can still produce a trophic cascade and affect the entire ecosystem.

Ecological pyramids graphically represent trophic levels in terms of number, biomass, or energy.

1. Pyramid of numbers:

• Shows the number of organisms at each trophic level.
• It is upright in grasslands because numerous plants support fewer herbivores and carnivores.
• It may be inverted in a tree ecosystem where one tree supports many insects and parasites.

2. Pyramid of biomass:

• Shows the dry mass of living matter at each trophic level at a given time.
• It is usually upright in terrestrial ecosystems.
• It may be inverted in aquatic ecosystems because phytoplankton have a small standing biomass but reproduce rapidly enough to support a larger consumer biomass.

3. Pyramid of energy:

• Shows energy flow per unit area per unit time.
• It is always upright because energy is lost as heat at every trophic transfer.

Thus, pyramids of numbers and biomass may be inverted, but the pyramid of energy cannot be inverted.

Ecological succession is the gradual and orderly change in the species composition and structure of a community over time.

Primary succession requires soil formation before larger plants can establish. Secondary succession proceeds faster because soil and some biological materials survive the disturbance. Both may eventually produce a relatively stable, mature community under prevailing environmental conditions.

The major stages of ecological succession are:

1. Nudation: A bare area is created by volcanic activity, erosion, glaciation, fire, or another disturbance.
2. Invasion: Species reach and establish in the area. It includes migration, establishment, and aggregation.
3. Competition and coaction: As populations increase, organisms compete for light, water, nutrients, food, and space.
4. Reaction: Organisms modify the environment. For example, lichens weather rock and add organic matter, making the habitat suitable for other species.
5. Seral replacement: Pioneer communities are gradually replaced by herbs, shrubs, and later communities as conditions change.
6. Stabilization: A comparatively stable community develops in balance with the prevailing climate, soil, and disturbance regime.

A typical lithosere may proceed as:

Bare rock lichens mosses herbs shrubs forest

Succession is dynamic, and recurring disturbances may prevent or redirect the development of a final community.

Environmental problems:

• Mining removes vegetation and destroys habitats.
• Open-cast mining causes soil erosion and landscape alteration.
• Mine drainage and processing chemicals contaminate water.
• Dust and toxic gases degrade air quality and affect health.
• Coal, petroleum, and natural gas combustion releases greenhouse gases and air pollutants.
• Oil spills damage marine and coastal ecosystems.
• Mining and large energy projects may displace local communities.
• Non-renewable reserves decline with continued extraction.

Remedial measures:

• Conduct environmental-impact assessments before projects begin.
• Use cleaner and more efficient extraction technologies.
• Restore mined land through backfilling, soil replacement, and revegetation.
• Treat mine wastewater and control dust and emissions.
• Recycle metals and design products for material recovery.
• Improve energy efficiency in buildings, industry, and transport.
• Replace fossil fuels progressively with low-carbon renewable energy.
• Ensure community participation, fair rehabilitation, and continuous environmental monitoring.

The most effective approach combines reduced consumption, circular use of materials, pollution control, and ecosystem restoration.

Natural-resource conservation and ecosystem processes are closely interconnected.

• Ecosystem structure consists of producers, consumers, decomposers, and abiotic components. Damage to land, water, or forests alters these components and their interactions.
• Energy flow depends on healthy producers. Deforestation, soil degradation, and water pollution reduce primary productivity and the energy available to higher trophic levels.
• Food chains and food webs transfer energy and help regulate populations. Overharvesting or habitat destruction can remove key species and destabilize these relationships.
• Nutrient cycling depends on decomposers and intact soil and water systems. Pollution can inhibit decomposition and disrupt nutrient availability.
• Ecological succession enables ecosystems to recover after disturbances. Severe or repeated exploitation may remove soil, seed banks, or source populations and delay recovery.
• Conservation measures, such as habitat protection, sustainable harvesting, pollution control, and ecological restoration, preserve ecosystem functions and improve resilience.

Therefore, conserving natural resources is not limited to protecting individual materials. It requires maintaining ecological relationships, natural regeneration, and the processes that support long-term productivity.