VALUE: After Hours (S07 E13): Trophic Cascades and Tariff Lessons

During their recent episode, Taylor, Carlisle, and Barry Ritholz discussed Trophic Cascades and Tariff Lessons. Here’s an excerpt from the episode:

So, first, trophic is derived from the Greek word for nourishment or food. And so, the trophic level in biology is basically each step in the food chain or the food web. So, first, a little bit of history lesson. In the early 20th century, wolves were deliberately eradicated from Yellowstone National Park through very aggressive hunting and trapping and poisoning. They were seen as a threat to livestock, and game and human safety. And so, we all said, “You got to go, wolves.”

So, by 1926, these targeted efforts had eliminated the last known pack from Yellowstone. As always, the most important question you should almost always be asking is, and then what? And in this case, in the wolves’ absence, the elk population exploded, because there wasn’t a predator to keep them under wraps. And so, they were grazing heavily on all these young trees. And then, these unchecked herbivores then led to the decline of many plant species which then affected other species. Beavers had less wood to harvest for their dam building. Birds lost their nesting grounds. River banks actually eroded, because there was deep rooted vegetation to hold the riverbank in place. And so, the literal shape of the topography of Yellowstone changed from this trophic cascade.

So, let’s fast forward a little bit. In the mid-1990s, these gray wolves were reintroduced after being extinct for decades. And then, of course, what happens next? There’s fewer elk, and then the elk actually started avoiding open meadows, like they were afraid to go in open meadows again, which then allowed willow trees to grow back. The beavers returned. The rivers literally changed course again, because their banks were stable and the entire landscape reshaped itself from a single top-level intervention. So, the key insight here is that ecosystems are deeply interconnected. Small changes at the top can create wide reaching effects that cascade throughout the entire system.

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