Ecology: Biology of Interactions. III-16. (Supplement) Ecosystem Efficiency and Energy Subsidies
Ecosystems can be supported by energy expenditures from outside. To prevent weeds from outcompeting wheat in a wheat field, humans add external energy inputs.
III-16. (supplement) Ecosystem efficiency and energy subsidies
Ecosystems may receive external energy subsidies that alter their functioning and apparent productivity. Agroecosystems are a key example: maintaining crop dominance requires additional energy inputs (labor, machinery, fertilizers, irrigation, pest control, transport, and storage).
Such subsidies increase target output but also change trophic structure, nutrient cycling, disturbance frequency, and system dependence on external flows. Therefore, high short-term yield does not necessarily indicate high autonomous ecosystem efficiency.
Assessment of ecosystem efficiency must distinguish internal ecological productivity from externally financed throughput. Sustainability analysis should include full energy accounting, including hidden and delayed costs.