Ecological Succession

To evaluate which statement is incorrect about ecological pyramids, we should review what ecological pyramids represent and their fundamental characteristics.

1. Exclusion of Saprophytes: Ecological pyramids typically depict the flow of energy, numbers, or biomass through different trophic levels in an ecosystem. Saprophytes, or decomposers, are usually not shown because they function at all levels by breaking down dead organic matter.

2. Inverted Pyramid of Numbers: In some ecosystems like forests, a single large tree may support many herbivores such as insects. This situation creates an inverted pyramid of numbers where the base (plants) is smaller than the primary consumer level.

3. Inverted Pyramid of Biomass: In ocean ecosystems, the biomass of phytoplankton is less than that of the zooplankton that feed on them due to rapid reproduction rates and turn over of phytoplankton, resulting in an inverted pyramid of biomass.

4. Species Overlapping Trophic Levels: Ecological pyramids typically assume that each organism only occupies one trophic level. However, some species can operate at multiple levels, such as omnivores that eat both plants and animals, but this is not depicted in these pyramids.

Given these clarifications, the wrong statement about ecological pyramids is: They consider the same species belonging to two or more trophic levels. Ecological pyramids generally do not account for species interacting across multiple trophic levels, which is why this statement is inaccurate.