Chapter 12: How Nature Works in Harmony

Elephants and Human Settlements

• Habitat pressures: Changing rainfall and temperature affect vegetation; cutting trees for roads and buildings worsens forest loss.
• Food and water: When vegetation is scarce and waterholes dry up, elephants may seek bananas, sugarcane and other food in nearby farms or plantations.
• Conflict: Crop damage may result, and people or domestic animals may sometimes be harmed.
• Where reported: Such elephant visits occur in parts of Odisha, Jharkhand, West Bengal, Assam and Chhattisgarh.
• Adaptation: Elephants are adapted to forest life, so sudden habitat changes can make survival difficult.

• Corridors: Identified and marked routes that allow wildlife to travel safely between large forest areas.
• Purpose: They support animal movement and help reduce conflict with human settlements.

Habitats and Their Components

• Living conditions: Different habitats provide different conditions; each organism needs suitable conditions to survive.
• Adaptation: Organisms adapt to survive in the surrounding conditions of their habitat.
• Biotic components: The living organisms in a habitat, such as fish, plants and birds.
• Abiotic components: The non-living things in a habitat, such as water and soil.
• Variation: Habitats may contain different organisms and different non-living components.

• Pond resources: A pond provides fish with food, oxygen, shelter and space to grow.
• Fish’s needs: Fish obtain food from small plants and animals, and oxygen from the water.
• Interactions: Organisms interact with other living beings and with the non-living parts of their habitat.

Pond Community

• Animals: Frogs, freshwater turtles, snakes, dragonflies, mosquitoes, snails and ducks can live in ponds.
• Plants: Pond plants include algae, diatoms, duckweeds and lotus.

• Physical conditions: Air, sunlight, water, temperature and soil are important features of a habitat.
• Different resource use: Organisms in the same habitat may use its resources in different ways.
• Changing conditions: A forest can be warm during the day and cool at night.
• Coexistence: A snake active at night and a rodent active during the day can share a habitat while facing different conditions; organisms coexist in harmony.

• Counting populations records how many individuals of different organisms live in a particular place at a given time.
• Example: A \(1\,\text{m} \times 1\,\text{m}\) area may contain 20 plants of one kind and 5 of another.
• Shared needs: If only one kind of organism lived in a habitat, its members would compete for the same food, water and space; resources could become scarce.

• Biotic components: Plants, animals and microorganisms together form the living community of a habitat.
• Interactions: Organisms in a community interact with and depend on one another for survival.

Flower Parts and Pollination

• Flower parts: A flower has a stalk, green leaf-like sepals, coloured petals, and reproductive parts: stamens (male) and carpels (female).
• Pollen transfer: Stamens release pollen grains; wind, water, insects, bats or birds can carry them to carpels.
• Importance: Pollination is essential for the formation of fruits and seeds.

Pond Study

• Observations: Pond A had fish and many flowering plants nearby; Pond B had no fish and fewer flowering plants.
• Predator relationship: Fish eat dragonfly larvae, so ponds with fish had fewer dragonflies.
• Pollinators: Dragonflies eat flies, bees and butterflies. With fewer dragonflies, more of these insects may be available to pollinate nearby flowers.
• Outcome: More pollination can help nearby plants produce more seeds.

Interactions in the Habitat

• Biotic components: Fish, dragonflies, pollinators and plants affect one another through their interactions.
• Abiotic components: Non-living factors such as water, temperature and nutrients also interact with and affect organisms.
• Balance: Overfishing can change the fish population and disturb the balance between living and non-living parts of the habitat.

Types of interactions

• Biotic–abiotic: Organisms interact with non-living components; these interactions can influence nutrition, respiration and reproduction.
• Biotic–biotic: Organisms depend on or affect one another for nutrition, respiration and reproduction, and for access to resources.
• Abiotic–abiotic: Non-living components interact and can influence the physical characteristics of a habitat.

Ecosystem features and types

• Interactions: Organisms interact with abiotic components for food, shelter and protection.
• Size and overlap: Ecosystems may be large or small, and different ecosystems can overlap and interact.
• Aquatic ecosystems: Include ponds, rivers and lakes.
• Terrestrial ecosystems: Include forests, grasslands and farms; even a large tree such as a banyan, mango or pilkhan can support an ecosystem.
• Human-made ecosystem: Farmland is an example.

How ecosystem components depend on one another

• Plants depend on abiotic components: Sunlight, carbon dioxide and water are needed for photosynthesis; soil provides a growing medium and essential nutrients.
• Air and water: Air supplies oxygen for respiration in plants and animals; water is essential for all living organisms.
• Plants affect abiotic components: They release oxygen, hold soil with their roots, reduce erosion, retain soil moisture and help cool the atmosphere.
• Organisms depend on one another for nutrition, respiration and reproduction, as well as resources such as food.

• Order: Individual organism → population → community → ecosystem.

Food-chain pyramid

• Arrangement: Organisms in a food chain can be placed in levels to form a pyramid.
• Crop-field example: Millet is at the base, mice feed on it, and an eagle occupies a higher level.
• Number pattern: In the illustrated crop-field pyramid, the greatest number is placed at the base and the smallest at the top.

Waste in an organism’s life cycle

• Waste: During life, organisms produce waste, including dead matter and food waste.

Maintaining Ecosystem Balance

• Dynamic balance is not fixed; populations and resources can change while the ecosystem remains balanced.
• Disruption can result from natural changes or human actions, such as pollution, overharvesting and pesticide use.
• Interdependence means a change in one population can cause a chain of effects across the ecosystem.