Environmental Science (Demo)

Ecosystems and Biodiversity

1. What is an Ecosystem?

  • A system that includes all biotic (living) and abiotic (non-living) components interacting in an environment.
  • Can range in scale from large (rainforests) to small (ponds).

2. Biotic and Abiotic Factors

  • Biotic: Plants, animals, fungi, bacteria.
  • Abiotic: Temperature, sunlight, water, soil, pH, oxygen, salinity.

3. Energy Flow in Ecosystems

  • Producers (Autotrophs): Perform photosynthesis (e.g., plants, algae).
  • Consumers (Heterotrophs):
    • Primary: Herbivores.
    • Secondary: Carnivores that eat herbivores.
    • Tertiary: Carnivores that eat other carnivores.
  • Decomposers: Break down dead matter (e.g., fungi, bacteria).
  • 10% Rule: Only ~10% of energy transfers between trophic levels.

4. Food Chains and Food Webs

  • Food Chain: Linear sequence of organisms consuming each other.
  • Food Web: Complex network of interconnected food chains.

5. Biodiversity

  • Genetic Diversity: Differences in genes among individuals.
  • Species Diversity: Number of different species.
  • Ecosystem Diversity: Variety of habitats.
  • Benefits: Stability, ecosystem services, resilience, medicine, food security.

6. Ecological Succession

  • Primary Succession: Starts on bare rock (e.g., volcanic island).
  • Secondary Succession: Begins after a disturbance (e.g., forest fire).
  • Leads to a climax community if undisturbed.

7. Keystone and Indicator Species

  • Keystone Species: Have a large impact on ecosystem structure (e.g., wolves, sea otters).
  • Indicator Species: Signal ecosystem health (e.g., frogs, lichens).

8. Threats to Biodiversity

  • Habitat Loss and Fragmentation
  • Pollution: Chemical, plastic, noise, light.
  • Invasive Species
  • Climate Change
  • Overexploitation: Overfishing, poaching.

Climate Change and Human Impact

1. Greenhouse Effect

  • Caused by greenhouse gases (GHGs) trapping heat in the atmosphere.
  • Major GHGs: CO₂, CH₄, N₂O, water vapor, CFCs.
  • Natural effect is essential, but human activity intensifies it.

2. Carbon Cycle Disruption

  • Human activities like fossil fuel burning, deforestation, and agriculture alter the natural carbon cycle.

3. Effects of Climate Change

  • Rising global temperatures.
  • Melting glaciers and ice caps → sea level rise.
  • More extreme weather events.
  • Ocean acidification affecting marine ecosystems.
  • Disruption of species habitats and migration patterns.

4. Human Population Growth

  • Increases demand for energy, food, and water.
  • Leads to urban sprawl, habitat destruction, and pollution.

5. Environmental Pollution

  • Air: CO, NOx, ozone, particulates.
  • Water: Runoff, sewage, oil spills.
  • Soil: Pesticides, heavy metals.
  • Light and Noise: Disrupt wildlife behavior and health.

6. Renewable Energy Solutions

  • Solar, wind, hydro, geothermal, biomass.
  • Advantages: Reduce GHG emissions, sustainable.
  • Challenges: Storage, grid integration, cost.

7. Climate Change Mitigation

  • Carbon taxes and cap-and-trade systems.
  • Reforestation, renewable energy, energy efficiency.
  • Public transport, green buildings, sustainable agriculture.

8. Adaptation Strategies

  • Flood defenses, drought-resistant crops, early warning systems.
  • Water conservation, infrastructure resilience.

9. Global Agreements and Policies

  • Kyoto Protocol (1997): First global treaty to reduce GHGs.
  • Paris Agreement (2015): Aim to limit global warming below 2°C, ideally 1.5°C.
  • IPCC Reports: Provide scientific basis for climate policy.