In a food pyramid, there is typically less biomass at the top (i.e., there are very few individual tertiary consumers, whereas there are numerous individual producers). In three to five sentences, explain this phenomenon, citing evidence relating to energy flow and how plants support ecosystems. (4 points)
The phenomenon of less biomass at the top of a food pyramid can be explained by the concept of energy flow in ecosystems. Energy is transferred from one trophic level to the next, but with each transfer, only a fraction of the energy is retained. This is known as the 10% rule, where approximately 10% of the energy is transferred to the next trophic level.
Since plants are the primary producers at the base of the pyramid, they convert sunlight energy into organic matter through photosynthesis, making them highly efficient at capturing and storing energy. As energy moves up the trophic levels through consumption, only a small portion of this energy is obtained by herbivores. This trend continues at higher trophic levels, resulting in a smaller biomass of tertiary consumers.
Evidence of this can be seen in ecological studies where the number and biomass of organisms decrease as we move up the food pyramid. For example, a study done in a forest ecosystem might show a large number of plants, a smaller number of herbivores feeding on those plants, and an even smaller number of carnivores that prey on the herbivores. The lower biomass at higher trophic levels is a result of the energy loss that occurs with each transfer.