2.2.28 (HL)—Ecological efficiency

Ecological efficiency is the fraction of energy at one trophic level transferred into production at the next.

Use efficiency = output production ÷ input production × 100. The remainder covers respiration, waste, uneaten material and other losses.

A herbivore level produces 80 kJ from 1,000 kJ of plant production: efficiency = 8%.

15% (12 ÷ 80 × 100); use the immediately preceding level as input.

Do not divide by the original producer input when calculating a single transfer; that gives a multi-step yield instead.