Cascades, trophic or otherwise, are a condition of complex systems

Trophic cascades have a very specific meaning but they are an instance of a much broader phenomenon.  From Wikipedia: 

Trophic cascades are powerful indirect interactions that can control entire ecosystems, occurring when a trophic level in a food web is suppressed. For example, a top-down cascade will occur if predators are effective enough in predation to reduce the abundance, or alter the behavior of their prey, thereby releasing the next lower trophic level from predation (or herbivory if the intermediate trophic level is a herbivore).

The trophic cascade is an ecological concept which has stimulated new research in many areas of ecology. For example, it can be important for understanding the knock-on effects of removing top predators from food webs, as humans have done in many places through hunting and fishing.

A top-down cascade is a trophic cascade where the top consumer/predator controls the primary consumer population. In turn, the primary producer population thrives. The removal of the top predator can alter the food web dynamics. In this case, the primary consumers would overpopulate and exploit the primary producers. Eventually there would not be enough primary producers to sustain the consumer population. Top-down food web stability depends on competition and predation in the higher trophic levels. Invasive species can also alter this cascade by removing or becoming a top predator. This interaction may not always be negative. Studies have shown that certain invasive species have begun to shift cascades; and as a consequence, ecosystem degradation has been repaired.

This is specifically a phenomenon in ecology.  A wonderful, brief, documentary illustrates the concept.

Double click to enlarge.

But the broader concept is important.  Ecology is merely one instance of a complex, dynamic, multi-system, non-linear, multi-causal, chaotic systems with hidden feedback mechanisms and uncertain tipping points.  And our lives are dominated by such systems.  The economy, the stock market, health, public policies, politics, etc. - they are all systems with low predictability or capacity for modeling.  

Our political and policy inclinations are always towards simple process planning but the issues we are tackling are complex systems.  There is a mismatch between technique and reality.

There are plenty of times and places and circumstances where we can process plan - define objectives, plan solutions, implement those controlled solutions in a disciplined fashion, with easy capacity to distinguish the desirable from the undesired outcomes.  We do that and often do it well where the process is simpler, less dynamic and stable.

And ost of our problems are wicked problems not stable simple problems.

Wicked problems do not lend themselves to planned solutions.  You lear while you do.  But there is much uncertainty and at most you can experiment your way to desirable outcomes.  It takes time, and there are failures along the way but wicked problems in complex evolving systems don't lend themselves to simple solutions.

In the video above, there is little mention of the many-year debate about the reintroduction of wolves into Yellowstone.  There were well founded concerns about the impact within the Park.  There were concerns about spillover effects in terms of ranching in surrounding areas.  The list of unknowns and uncertainties were long and unprovable and unresolvable.  

Except by experimentation.  Which was what the reintroduction of wolves to Yellowstone was.  A brave experiment.

The video highlights the positive outcomes.  There have been some negatives as well.  I would guess that on balance most stakeholders might agree that the benefits are greater than had been expected and that the negative outcomes either did not manifest or manifested to a less degree than had been expected.

And within the different stakeholder groups some would have experienced very positive outcomes while some might have borne very significant costs.  

The point though, is that complex systems cannot be predicted or solved.  The best you can do plan, discuss, measure, monitor, acknowledge multiple stake holder interests and multiple measurable objectives and then role the die.