IB Biology D4.2 – Stability and Change Notes

Vocabulary flashcards covering key terms and concepts from IB Biology topic D4.2 on ecosystem stability, sustainability, pollution, and rewilding.

Ecosystem

A biological community of interacting organisms and their physical environment.

Biotic Factors

The living components of an ecosystem, including producers, consumers, and decomposers.

Producers / Autotrophs

Organisms that synthesize their own food from inorganic substances, typically via photosynthesis.

Consumers / Heterotrophs

Organisms that obtain energy by feeding on other organisms.

Decomposers

Organisms that break down dead organic matter, recycling nutrients back into the ecosystem.

Abiotic Factors

Non-living components of an ecosystem such as sunlight, water, and temperature.

Ecosystem Stability

The ability of an ecosystem to remain unchanged or recover after disturbance over long periods.

Kalahari Desert

A 60-million-year-old desert cited as evidence of long-term ecosystem stability.

Tropical Rainforest

A stable, biodiverse ecosystem characterized by high precipitation and warm temperatures.

Energy Supply

A continuous input of sunlight that supports photosynthesis and food webs in an ecosystem.

Nutrient Recycling

The continual movement of elements like nitrogen and phosphorus through biotic and abiotic components.

Genetic Diversity

The variety of genes within a population that enhances resilience to environmental change.

Climatic Tolerance Range

The set of environmental conditions that must stay within limits for ecosystem stability.

Tipping Point

A critical threshold that, once crossed, triggers large and often irreversible ecosystem change.

Amazon Rainforest Tipping Point

A hypothesized loss of forest area beyond which Amazonian climate regulation collapses.

Percentage Change Formula

(Final − Initial) ÷ Initial × 100, used to calculate deforestation rates.

Mesocosm

A controlled, enclosed experimental ecosystem used to study ecological processes.

Resource Harvesting Sustainability

Extraction of natural resources at a rate equal to or lower than their natural replacement.

Sustainable Fishing

Harvesting fish stocks at a rate that does not reduce long-term population sizes.

Maximum Sustainable Yield

The largest catch that can be taken over time without depleting a fish stock.

Pacific Cod Case Study

An example where tagging and echo-sounder data guide sustainable harvest quotas.

Silver Thatch (Tom) Palm

A plant harvested sustainably by removing regenerating leaves while monitoring populations.

Sustainable Agriculture

Food production methods that meet current needs while preserving soil, water, and biodiversity.

Soil Erosion

Loss of topsoil due to wind or water, reducing agricultural fertility.

Nutrient Leaching

Drainage of dissolved nutrients from soil into waterways, often causing eutrophication.

Fertilizer Inputs

Manufactured nutrients whose production and overuse can harm ecosystems.

Agrochemical Pollution

Long-term soil and water contamination from pesticides and herbicides.

Carbon Footprint (Agriculture)

Total greenhouse-gas emissions produced by farming activities.

Plastic

Synthetic organic material that is persistent in nature due to non-biodegradability.

Macroplastic

Plastic debris larger than 1 mm, easily visible in the environment.

Microplastic

Plastic fragments smaller than 1 mm formed by breakdown of larger pieces.

Laysan Albatross Impact

Bird mortality caused by ingestion of floating plastics mistaken for food.

Sea Turtle Impact

Injury or death from plastics lodged in the esophagus or entangling limbs.

Scientific Communication

Researchers sharing findings to influence public actions on environmental issues.

Media Influence

Coverage that shapes global perception and drives policy on problems like plastic pollution.

Rewilding

Restoring degraded ecosystems by reducing human impact and reintroducing native species.

Keystone Species

Species whose ecological role has a disproportionate effect on community structure.

Wildlife Corridor

Habitat link that connects separated populations, promoting migration and gene flow.

Hinewai Reserve

A New Zealand project (est. 1987) showcasing rewilding through native forest regeneration.