pyramid of biomass A diagrammatic expression of biomass at different trophic levels in an ecosystem, usually plotted as dry matter or calorific value per unit area or volume. Typically, this gives a gradually sloping pyramid, except where the sizes of organisms vary dramatically from one trophic level to another. In this case, the higher metabolic rate of the smaller organisms may result in a greater biomass of consumers than of producers, giving an inverted pyramid. Aquatic communities in winter typically show inverted biomass pyramids. Compare PYRAMID OF ENERGY and PYRAMID OF NUMBERS; see also ECOLOGICAL PYRAMID.

pyramid of biomass A diagrammatic representation of the amount of organic material (see biomass), measured in grams of dry mass per square metre (g m^–2), found in a particular habitat at ascending trophic levels of a food chain. Biomass decreases at each ascending level of the food chain. A pyramid of biomass is a more accurate representation of the flow of energy through a food chain than a pyramid of numbers, but seasonal variations in the rate of turnover of the organisms at a particular level may result in higher or lower values for the amount of biomass sampled at a particular time than the average amount over the whole year. The best representation of energy flow in a food chain is a pyramid of energy.

pyramid of biomass A diagrammatic expression of biomass at different trophic levels in an ecosystem, usually plotted as dry matter or calorific value per unit area or volume. Typically this gives a gradually sloping pyramid, except where the sizes of organisms vary dramatically from one trophic level to another. In this case, the higher metabolic rate of the smaller organisms may result in a greater biomass of consumers than of producers, giving an inverted pyramid. Aquatic communities in winter typically show inverted biomass pyramids. Compare pyramid of energy and pyramid of numbers; see also ecological pyramid.

pyramid of biomass A diagrammatic expression of biomass at different trophic levels in an ecosystem, usually plotted as dry matter per unit area or volume. Typically this gives a gradually sloping pyramid, except where the sizes of organisms vary dramatically from one trophic level to another. In this case, the higher metabolic rate of the smaller organisms may result in a greater biomass of consumers than of producers, giving an inverted pyramid. Aquatic communities in winter typically show inverted biomass pyramids. Compare PYRAMID OF ENERGY; PYRAMID OF NUMBERS. See also ECOLOGICAL PYRAMID.