Ecosystems and Sustainability Notes

Sustainability: Ability of a system to continue indefinitely.
Ecosystems: Potentially sustainable, e.g., Daintree Rainforest, which has existed for over 100 million years due to stable climate.
Maintaining Sustainability:
- Steady energy supply (usually sunlight).
- Replenishment of nutrient cycles.
Ecosystem Resilience: Limited; disturbance can lead to a tipping point.
Tipping Points: Beyond a certain level of disturbance, positive feedback mechanisms cause irreversible changes, e.g., deforestation in the Amazon rainforest leading to grassland.

Climatic Variables: Temperature and rainfall must remain within tolerance ranges.
Genetic Diversity: High diversity in keystone species is essential for adaptation to environmental changes.

Formula: $\frac{\text{final amount} - \text{initial amount}}{\text{initial amount}} \times 100\%$ .
Example: Calculation of percentage change in the area of Amazon rainforest.

Mesocosms: Small experimental enclosures used to model ecosystems.
Essential Components: Autotrophs and saprotrophs are crucial for sustainability.
Ethics: Large animals should not be subjected to suffering in mesocosms.

Definition: A species with a disproportionate impact on its community.
Loss: Can lead to decreased species diversity and ecosystem collapse.
Example: Pisaster ochraceus (sea star) predation maintains biodiversity on rocky shores.

Principle: Harvesting rate must be lower than the replacement rate.
Unsustainable Harvesting: Has led to species extinctions.
Brazil Nuts: Sustainable harvesting depends on leaving nuts to germinate.
Atlantic Cod: Overfishing led to population collapse; sustainability requires international cooperation and adhering to the maximum sustainable yield.
Maximum Sustainable Yield: Point M on a sigmoid growth curve, where population growth is at its maximum.

Intensive Methods: Can increase yields but reduce sustainability.
Tillage: Can degrade soil structure and cause erosion.
Nutrient Depletion: Requires repeated fertilizer applications, which consume energy and mineral resources.
Monoculture: Encourages pests and weeds, leading to pesticide use and pollution.
Carbon Footprint: Agriculture contributes significantly to climate change.

Definition: Nutrient enrichment of aquatic ecosystems due to leaching from agriculture.
Causes: Use of artificial fertilizers and improper storage/application of manure.
Consequences: Excessive algae growth, oxygen depletion, and death of aquatic organisms.

Accumulation: Oceans contain vast quantities of plastic due to slow degradation.
Macroplastics: Entanglement and ingestion by marine wildlife.
Microplastics: Ingested by filter-feeders, accumulate toxic compounds.
Nanoplastics: Can enter cells and accumulate in organs, with largely unknown harmful effects.

Bioaccumulation: Increase in toxin concentration in body tissues over an animal's life.
Biomagnification: Increase in toxin concentration at successive trophic levels.
Example: DDT caused population declines in birds of prey.

Principle: Minimal human intervention to restore natural ecosystems.
Steps:
- Reducing human activities like agriculture and logging.
- Reintroduction of keystone species.
- Control of invasive species.

Definition: Progressive changes that transform ecosystems over time.
Trigger: Abiotic or biotic factors that initiate change.
Primary Succession: Begins in environments devoid of or lacking organisms, such as bare rock.
Sand Dunes: Illustrate primary succession; species diversity, primary production, food webs, soil depth and nutrient cycling increase.

Deflected Succession: Human activities can prevent the development of a climax community.
Plagioclimax: An alternative stable community maintained by human influence.
Examples: Grazing leading to grassland, drainage of wetlands.