Welcome the Beavers…Trophic Cascade

It’s the middle of winter and I’m dreaming about summer, listening to a PlanetGeo podcast on Yellowstone.  The podcasters, if that is a real word, are talking about some biological situations existing within Yellowstone, starting with how the introduction of the invasive lake trout caused the decimation of the cut-throat trout and then transitioned to the re-introduction of the wolves in 1995.   They threw out that, with the introduction of wolves, beavers came back.  Huh?  What is the connection?  Can you see it? (HINT: pause, think about it)

I admit, the connection of how adding wolves causes growth in beaver population evaded me – I was missing the intermediate connections.  Once the Yellowstone wolves were hunted to extinction in the 1920s, their primary prey, the elk got fat and lazy.  They would lazily graze on willow shoots along the riverbanks.  New.nsf.com captures the situation this way:

The loss of wolves caused far-reaching changes in the Yellowstone ecosystem: more elk and fewer willows. With no willows to slow stream flow, creeks flowed faster and faster. Beavers prefer slow-moving waters, so they disappeared with the willows.

With the controversial wolf re-introduction , the elk were forced to adapt or be eaten, leaving and allowing the willows to grow.   Beavers, who thrive on willows, return and streams become beaver ponds, bogs, etc. and the complex ecosystem recovers.

PlanetGeo calls these examples trophic cascades, to which nature.com adds, powerful indirect interactions that can control entire ecosystems. Trophic cascades occur when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level.

Question for you – can you think of other trophic cascade examples, either in nature OR in your lives?

A friend of mine, we’ll call him Todd, would throw out the “buggy whip guy.”  One day, the “buggy whip guy” is living his best life as the market share leader of horse buggy whips, aware of but unconcerned about the motor cars puttering around him.  Motor cars that are unreliable and too expensive for the ordinary guy – too expensive until Ford introduces the assembly line, the forerunner of Lean Manufacturing.  Ouch!  Unique example – hardly

So – moral of the story?  Go to Yellowstone!  Beware becoming “fat and lazy,” rather “adapt or be eaten.”