Key Terms: Ecosystems (AQA GCSE Geography): Revision Note

Ecosystems - key terms glossary

Abiotic – The non-living parts of an ecosystem such as sunlight, water, temperature, and soil.

Ash dieback – A tree disease affecting UK woodlands, which leads to knock-on effects across the food web.

Biodiversity – The variety of plant and animal species in an ecosystem, affected by factors like climate, habitat availability, and food supply.

Biome – A large-scale ecosystem defined by its climate, vegetation, and wildlife (e.g. tropical rainforest, desert, tundra).

Biotic – The living components of an ecosystem, such as plants, animals, fungi, and bacteria.

Climate change – Long-term alterations in temperature and weather patterns, often human-induced, which affect ecosystems globally.

Consumer – An organism that gets its energy by eating other organisms; includes primary (herbivores), secondary (carnivores), and tertiary consumers (top predators).

Deciduous woodland – A UK ecosystem with trees that lose their leaves in winter; examples include oak, ash, and beech trees.

Decomposer – Microorganisms like fungi and bacteria that break down dead organic material, returning nutrients to the soil.

Deforestation – The clearing or thinning of forests by humans, often leading to habitat loss and ecosystem imbalance.

Ecosystem – A community of living organisms (biotic) interacting with the non-living environment (abiotic).

Food chain – A linear sequence showing how energy is transferred from one organism to another through feeding.

Food web – A complex network of interconnected food chains within an ecosystem showing how organisms feed on multiple sources.

Habitat – The natural environment where a plant or animal lives, providing food, water, and shelter.

Interdependence – The way biotic and abiotic components in an ecosystem rely on one another, meaning changes in one part can affect others.

Invasive species – Non-native organisms introduced into an ecosystem that outcompete native species (e.g. grey squirrels in the UK).

Latitude – The distance north or south of the equator, which influences climate and biome distribution.

Nutrient cycle – The continuous movement and exchange of organic and inorganic matter back into the production of living matter.

Ocean currents – Large-scale movements of seawater that influence coastal climate conditions and biome characteristics.

Producer – An organism, typically a plant or algae, that makes its own food using photosynthesis and forms the base of the food chain.

Stable ecosystem – An ecosystem where the biotic and abiotic components are balanced, leading to consistent population levels over time.

Trophic level – A step in the food chain occupied by organisms with a similar feeding role (e.g., producer, primary consumer).