Title: key concepts
Course: What can WE do for biodiversity? The European Strategies for habitat conservation > Section: 1_A tale of succes: behind the Iberian lynx tracks

When one organism feeds on another, a flow of energy occurs between them.

The energy flow of an ecosystem follows the path of the existing feeding relationships. It is firs transferred from producers to primary consumers, then from primary to secondary consumers, etc., until it reaches decomposers through organic wastes.

All organisms extract the energy they need to survive from food. Once it has been used, energy is lost in the form of heat and cannot be reused.

Therefore, food is consumed as it moves through trophic levels, and the energy stored in this food is absorbed until it is all used up. That’s why energy also needs to be obtained from an external source: this is the only way producers can produce new food.

When the energy transferred from one trophic level to the next is represented in an orderly manner, you can see how the amount of energy available quickly decreases.

The model that represents the flow of energy between levels is a diagram called an energy pyramid. The pyramid structure is the same for all ecosystems, and shows how the energy available decreases from one level to the next one.

The decrease in available energy happens for these reasons:

·      Within each trophic level, organisms consume most of the food through cellular respiration to get the energy they need to survive.

·      Some of the food available is not consumed, and it moves directly to the decomposer level.

A pyramid of energy [1]

[1] By Swiggity.Swag.YOLO.Bro - Extracted from this Commons file, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=85276916