Question bank: Ecology: Ecological Pyramids

Ecological pyramids are graphical representations that show the trophic structure of an ecosystem, that is, the relationship between different trophic levels such as producers, primary consumers, secondary consumers, etc., and decomposers, and the amount of energy, biomass, or number of individuals at each level. The energy pyramid is the most representative for evaluating energy flow because it shows the amount of energy available at each trophic level and the efficiency in energy transfer between them. The main elements of an energy pyramid are: (1) Producers, which are the base and hold the most energy, (2) Primary consumers, (3) Secondary consumers, (4) Tertiary consumers, and so on, with energy decreasing at each trophic level due to thermal and metabolic losses. This pyramid is more relevant because energy is the basis of all biological activities and is the way in which ecosystem productivity is measured. Biomass and number of individuals pyramids are less representative because biomass can vary with seasonal changes and the physical structure of organisms, while the number of individuals does not reflect the amount of transferred energy, as smaller organisms can have a high metabolic rate and therefore a high energy consumption despite their small biomass.

In a tropical forest ecosystem, the energy pyramid has a typical shape, where energy decreases as it passes through the trophic levels. Suppose that, at the first trophic level, the total primary biomass produced annually by the producers is 1,000,000 kcal. At the second trophic level, the biomass of primary consumers is 300,000 kcal and, at the third level, the biomass of secondary consumers is 90,000 kcal. Based on these values and the understanding of how energy disperses in ecological pyramids, answer: (1) Explain what each trophic level represents in terms of organisms and energy transfer. (2) Discuss what the shape of the energy pyramid suggests about the ecosystem's energy efficiency and the implications for its ecological stability.

The degradation of ecosystems and the loss of biodiversity can compromise the functionality of ecological pyramids, as well as the balance of ecosystems. First, explain what ecological pyramids are and identify the three main types. Then, discuss how human actions can affect these ecological pyramids and, consequently, ecosystems. Finally, emphasize the importance of environmental policies for ensuring the sustainability of the planet.

In a tropical Amazon rainforest area, analyses were conducted to verify the amount of energy and biomass stored in the different trophic levels of the ecosystem. Based on the topic 'Ecological Pyramids', describe what ecological pyramids are, identify and explain the three main types of pyramids, and discuss the effects of human actions on these pyramids, considering the importance of biodiversity preservation and conservation and the influence of environmental policies to ensure the sustainability of the planet.