Trophic Cascade

A trophic cascade is an ecological effect in which a change at one level of a food web, most often a change in the population of a top predator, triggers a chain reaction of population changes that ripple down through the lower levels of the same food web, ultimately altering the abundance of species, or even the physical structure of the habitat, at levels far removed from where the original change occurred. Ecologist Robert Paine's field experiments in the 1960s, in which he physically removed a starfish predator from a rocky intertidal shoreline and documented the resulting collapse in the diversity of species below it in the food web, provided some of the earliest clear experimental evidence for the concept, and the term trophic cascade itself was introduced into wider ecological use by researchers including Stephen Carpenter and James Kitchell in the 1980s. One of the most widely cited real-world examples is the documented ecological effect of reintroducing gray wolves to Yellowstone National Park in 1995, which was followed by a reduction in elk browsing pressure and a subsequent documented recovery of streamside vegetation, illustrating how a change at the top of a food web can propagate down through multiple trophic levels. Trophic cascades are now recognized as a significant and well-documented ecological phenomenon relevant to conservation and wildlife management, particularly for understanding the broader ecosystem consequences of removing or restoring a top predator.