Organisation of an ecosystem - EdexcelPyramids of biomass
The feeding relationships between organisms in an ecosystem can be seen in food chains. Sampling allows us to measure the abundance and distribution of these species.
biomassThe dry mass of an organism. is living or recently dead tissues. The mass of your body is biomass because you are alive. Wood is considered biomass because it was recently a plant. Fossil fuels are not considered biomass because they are the remains of organisms that died millions of years ago and have been chemically changed from the original living tissue.
Pyramids of biomass
The amount of biomass can be measured at different trophic levelThe position of an organism in a food chain, food web or pyramid. in a food chain. The total biomass of each trophic level is often represented as a modified bar chart called a pyramid of biomass. In a food chainA sequence (usually shown as a diagram) of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels. from a healthy ecosystemThe living organisms in a particular area, together with the non-living components of the environment. the biomass at each trophic level must reduce. An example of a food chain is:
clover → snail → thrush → sparrowhawk
So in an ecosystem the clover has more biomass than all the snails, which have more biomass than all the thrushes and so on. Pyramids of biomass are always perfectly shaped. If this is not the case, then the ecosystem is likely to be unhealthy and in danger.
Pyramids of biomass must be drawn with the:
bars equally spaced around the midpoint
bars touching
bar for the producerPlants that begin food chains by making energy from carbon dioxide and water. at the bottom
length of each bar is proportional to the amount of biomass available at each trophic level