IB Environmental systems and societies 2.2I Productivity and Ecological Efficiency Key Definitions

Ecological efficiency refers to the percentage of energy that is transferred from one trophic level to the next in an ecosystem.

Entropy refers to the measure of disorder or randomness within a system.

Gross Primary Productivity (GPP) refers to the total amount of energy captured by producers (typically plants and algae) through photosynthesis.

Maximum sustainable yield (MSY) is the largest amount of biomass that can be harvested from an ecosystem without depleting its resources, ensuring long-term sustainability.

Net Primary Productivity (NPP) refers to the amount of carbon that is captured by plants through photosynthesis and is available for growth and reproduction after subtracting the energy used by the plants for cellular respiration.

Primary productivity is the rate of production of biomass using an external energy source and inorganic sources of carbon and other elements.

Secondary productivity refers to the gain in biomass by consumers (such as herbivores, carnivores, and omnivores) through the assimilation of carbon compounds from the food they ingest.

The sustainable yield is the maximum amount of water that can be withdrawn from the system without reducing its capacity to regenerate.