Ecosystem and Biodiversity

Human Impact on the Ecosystem

Monoculture

• Monoculture: Growing a single crop species over a large area.

Advantages:

• Efficiency in farming: Easier to plant, harvest, and manage using machines.
• Higher yields: Farmers specialize in high-demand crops, increasing food production.
• Predictable growth patterns: Easier pest and fertilizer management due to uniformity.

Disadvantages:

• Soil degradation: Continuous farming of the same crop depletes nutrients, reducing soil fertility.
• Increased pest and disease vulnerability: Pests that specialize in the crop can spread rapidly; single infection can wipe out all crops.
• High chemical use: Requires more fertilizers, herbicides, and pesticides, leading to pollution.
• Loss of biodiversity: Disrupts food chains and webs, leading to habitat loss.

Deforestation

• Deforestation: Large-scale removal of trees, often for agriculture, urban development, or logging.

Reasons:

• Agricultural expansion: Land cleared for crops like soy, palm oil, and livestock grazing.
• Urbanization: Growing populations require land for housing and infrastructure.
• Timber extraction: Wood used for construction, paper, and fuel.

Effects:

• Loss of biodiversity: Many species lose habitat, leading to extinction.
• Soil erosion: Trees stabilize soil; without them, wind and rain wash away nutrients.
• Increased carbon dioxide (CO₂) levels: Trees absorb CO₂; cutting them contributes to the greenhouse effect.

Enhanced Greenhouse Effect

• Greenhouse effect: A natural process that traps heat in Earth’s atmosphere; human activities enhance this effect, leading to global warming.

Major Greenhouse Gases:

• Carbon dioxide (CO₂): Burning fossil fuels and deforestation.
  • CO_2
• Methane (CH₄): Released from cattle digestion (intensive farming), rice paddies, and landfills.
  • CH_4
• Nitrous oxide (N₂O): Emitted from fertilizers and industrial processes.
  • N_2O
• Water vapor (H₂O): Naturally occurring but influenced by temperature increases.
  • H_2O

Effects of the Enhanced Greenhouse Effect:

• Global warming: Increased temperatures cause climate changes.
• Rising sea levels: Melting polar ice leads to flooding.
• Extreme weather events: More frequent hurricanes, droughts, and heatwaves.
• Increased pest attacks

Intensive Livestock Farming

• Intensive livestock farming: Keeping large numbers of animals in confined spaces for maximum meat, egg, and dairy production.

Disadvantages:

• Animal Welfare Issues: Overcrowding leads to stress, injuries, and suffering.
• Disease Spread: High-density conditions promote the spread of infections like avian flu.
• Antibiotic Resistance: Overuse of antibiotics to prevent disease can lead to drug-resistant bacteria.
• High Greenhouse Gas Emissions: Methane from cattle contributes to climate change.
• Water and Land Pollution: Animal waste and fertilizers contaminate nearby water bodies.

Eutrophication

• Eutrophication: Excessive growth of algae in water bodies due to nutrient pollution, mainly from fertilizers and sewage.

Stages:

• Nutrient runoff: Fertilizers (containing nitrates & phosphates) wash into lakes and rivers.
• Algal bloom: Nutrients cause rapid growth of algae, blocking sunlight.
• Death of plants: Without sunlight, aquatic plants and algae die, reducing oxygen production.
• Decomposition: Bacteria decompose dead plants, using up oxygen through aerobic respiration.
• Oxygen depletion: Low oxygen levels cause fish and other aquatic life to suffocate.

Plastics

• Plastics: Non-biodegradable and persist in the environment for centuries.

Effects on the Environment:

• Harm to marine life: Turtles, fish, and seabirds ingest plastics, leading to suffocation, digestive blockage, or entanglement.
• Microplastics pollution: Small plastic particles enter the food chain, causing bioaccumulation.
• Soil and water contamination: Plastics leach toxic chemicals into the environment.

Invasive Species

• Invasive species: A non-native organism that spreads rapidly in a new environment, often harming local ecosystems.

Characteristics:

• Fast reproduction: Outcompetes native species for resources.
• Few natural predators: Unchecked population growth.
• Aggressive competition: Can lead to local species extinction.
• Example: Cane Toad (Australia). Introduced to control pests but became an invasive species by eating native species and poisoning predators.

Sustainable Resources

• Sustainable resource: One that is produced or replenished as quickly as it is consumed, ensuring that it does not run out.

Requirements:

• Rate of use = Rate of replenishment
• The resource is not permanently depleted.
• Future generations can continue to benefit from it.

Examples:

• Forests: Sustainable logging ensures new trees are planted as fast as they are cut.
• Fish stocks: Fishing regulations help maintain population sizes so fish can reproduce.

Why Conserve Natural Resources?

• Conservation programs: Essential for protecting species and preserving ecosystems.

Benefits:

• Maintaining/Increasing Biodiversity
  • Ensures ecosystem stability and survival of species.
  • Prevents loss of important genetic traits.
  • Supports ecosystems that provide oxygen, clean water, and fertile soil.
• Reducing Extinction
  • Many species face habitat destruction, hunting, and climate change.
  • Conservation efforts help restore populations and prevent extinction (e.g., pandas).
  • Protects species that play key roles in ecosystems, such as pollinators.
• Protecting Vulnerable Ecosystems
  • Certain ecosystems (e.g., rainforests, coral reefs) are highly sensitive to change.
  • Conservation programs prevent deforestation, pollution, and habitat destruction.
  • Protects keystone species that maintain the ecosystem's balance.
• Maintaining Ecosystem Functions
  • Ecosystems provide essential resources and support nutrient cycling.
    • Nutrient Cycling: Ensures continuous decomposition and recycling of carbon, nitrogen, and water; prevents depletion of essential nutrients in soil and water.
    • Resource Provision: Food (fish, fruits, crops), Drugs (medicinal plants like quinine, penicillin), Fuel (wood, biofuels, fossil fuels), Genes (wild species provide valuable genetic traits for crop improvement).

Sustainable Conservation of Forests and Fish Stocks

Forests:

• Sustainable forestry practices include selective logging and reforestation.
• Preventing illegal logging and enforcing protected areas.
• Encouraging eco-friendly products like recycled paper.
• Setting quotas and establishing heavy fines
• Spread education and awareness

Fish Stocks:

• Fishing quotas limit the number of fish caught.
• Size limits prevent catching young fish before they reproduce.
• Protected marine reserves allow fish populations to recover.
• Nets with larger mesh size to allow small fish to escape and breed.

Causes of Endangerment and Extinction

• Climate Change: Rising temperatures destroy habitats; extreme weather events disrupt food sources.
• Habitat Destruction: Deforestation removes homes for species; urbanization and agriculture reduce available land for wildlife.
• Hunting and Poaching: Illegal trade of animal parts; overhunting leads to population decline.
• Overharvesting: Overfishing reduces species populations; unsustainable agriculture depletes plant species.
• Pollution: Oil spills harm marine life; plastic waste is ingested by animals; pesticides kill essential pollinators.
• Introduced (Invasive) Species: Non-native species outcompete local species; lack of natural predators allows them to spread uncontrollably.

How to Conserve Endangered Species

• Monitoring and Protecting Species and Habitats
  • Wildlife reserves & national parks provide safe habitats.
  • Anti-poaching laws prevent illegal hunting.
  • Habitat restoration reverses deforestation and pollution effects.
• Education
  • Raises awareness on conservation issues; encourages sustainable living; supports eco-tourism.
• Captive Breeding Programs
  • Zoos and conservation centers breed endangered species; reintroduction into the wild helps repopulate areas; prevents inbreeding.
• Seed Banks
  • Stores seeds of rare plants to prevent extinction; can be grown later if natural populations decline. Example: Kew Millennium Seed Bank in the UK.

Issues with a Low Population

• Risks of Population Decline and Loss of Genetic Variation

Problems

• Inbreeding: Small populations breed with close relatives, leading to harmful mutations; causes weak immune systems, lower fertility, and genetic disorders.
• Reduced Adaptability: Less genetic variation means species cannot adapt to environmental changes; increases risk of extinction.
• Lower Survival Rates: Fewer individuals mean higher vulnerability to disasters; small populations struggle to recover quickly.

Importance of AI & IVF

Captive breeding programs help endangered species reproduce safely under human care.

• Artificial Insemination (AI): Sperm is collected from a male and artificially inserted into a female’s reproductive system; used when animals are difficult to breed naturally; allows genetic diversity.
• In Vitro Fertilization (IVF): Egg and sperm are combined outside the body in a lab; the fertilized egg is implanted into a female's uterus; allows reproduction in species that have fertility issues. Examples: AI and IVF have been used for pandas, rhinos, and cheetahs in zoos; helps species repopulate and prevent extinction.