Key Terms

📖 Key Terms

ecosystem services — The benefits that humans obtain from ecosystems, including provisioning services (food, water, medicine), regulating services (climate regulation, flood control, water purification), cultural services (tourism, recreation, spiritual value), and supporting services (soil formation, nutrient cycling). Total estimated value: $125–145 trillion/year globally.

biodiversity — The variety of living organisms in an ecosystem, measured at three levels: genetic diversity (variation within a species), species diversity (number of different species), and ecosystem diversity (variety of different ecosystem types). High biodiversity generally means greater ecosystem resilience — if one species is lost, others can partially fill its ecological role.

sustainable management — Managing an ecosystem in a way that meets the needs of current users without compromising the ability of future generations to meet their own needs. In practice, it means balancing ecological protection with economic use, and ensuring local communities benefit from conservation.

coral bleaching — The whitening and death of coral caused by elevated ocean temperatures. When water temperature rises 1–2°C above the summer maximum, coral expels the photosynthetic algae (zooxanthellae) living in its tissue. Without the algae, the coral turns white, loses its food source, and dies if temperatures remain elevated. The 2016 mass bleaching event killed 50% of the Great Barrier Reef's shallow-water coral.

rewilding — A conservation approach that involves removing intensive human management from an area and allowing natural ecological processes to reassert themselves, typically including the reintroduction of keystone species (large herbivores or predators) to restore natural grazing and predator-prey dynamics. Knepp Estate in West Sussex is the UK's leading rewilding project.

REDD+ — Reducing Emissions from Deforestation and forest Degradation — an international mechanism through which rich countries pay developing countries to protect their forests rather than clear them, using carbon credits traded on international markets. Operates in the Congo Basin, Amazon, and Southeast Asian forests.

zoning — Dividing a protected area into zones with different permitted uses, typically ranging from strictly protected no-take zones (no human activity) to general use zones (fishing and tourism permitted). Used in the Great Barrier Reef Marine Park, where 33% of the park is now no-take zone.

invasive species — A species introduced (deliberately or accidentally) to an ecosystem where it did not previously exist, which outcompetes, predates, or transmits disease to native species. Examples: grey squirrels vs red squirrels (UK); Nile perch wiping out 200 cichlid species in Lake Victoria; Japanese knotweed.

dead zone — An area of ocean or freshwater with such low oxygen levels that most marine life cannot survive there, typically caused by agricultural run-off triggering algae blooms whose decomposition consumes dissolved oxygen. The Gulf of Mexico dead zone covers ~22,000 km².