Biomass is the mass of living material. A pyramid of biomass shows the relative amount of biomass at each trophic level in a food chain. Trophic level 1, the producers, is always at the bottom of the pyramid.
To construct a pyramid of biomass, draw one horizontal bar for each trophic level, one above the other. Each bar is drawn to scale, so its length is proportional to the biomass at that level. Use the same scale for every bar. For example, if the producers have a biomass of 1000 kg and the primary consumers 500 kg, the bottom bar is twice as long as the bar above it.
Draw the bars centred on the same vertical line. Label each bar with the organism or trophic level, and give the scale. A pyramid of biomass is nearly always a pyramid shape, because there is less biomass at each level going up the food chain.
