Definition of Trophic Cascade? Top down vs Bottom up Trophic Cascade

What is a Trophic Cascade? Top down vs Bottom up Trophic Cascade

Trophic cascade is an ecological phenomenon that has significant effect on the overall structure and stability of an ecosystem.The term trophic cascade was coined by the famous American ecologist Robert Paine.

Trophic cascade is an indirect effect by predators that changes biomass, abundance or productivity of a population, community at successively lower trophic levels or trophic level across more than one link in a food chain.

These are powerful indirect interactions that can control the entire ecosystem.

The most common type of trophic cascade is three level trophic cascade that involves three trophic levels or feeding levels.

Top down Trophic cascade

Here the predators influence the abundance or biomass of a population at lower trophic levels.

Take this example. In the above figure, the tiger population (predator) has direct effect on the abundance of prey population. By controlling the prey population the predator indirectly influences the abundance or productivity at the producer level. This type of indirect influence at lower trophic levels by predators is termed as Top down trophic cascade.

Bottom up Trophic cascade

Here the Space or nutrients influence the abundance or biomass of a population at higher trophic levels.

In the above figure, lack of space or nutrients may lead to poor productivity at the producer level (amount of grass, no of fruits etc). This limits the number of prey population that will influence the number of predators. This type of indirect influence on higher trophic levels by lack of space or nutrients is termed as bottom up trophic cascade.