I just signed the petition, “Washington state Fish and Wildlife Director Jim Unsworth: Stop the killing of an endangered wolf pack in Washington.”
I think this is important. Will you sign it too?
How Wolves Change Rivers
When wolves were reintroduced to Yellowstone National Park in the United States after being absent nearly 70 years, the most remarkable “trophic cascade” occurred. What is a trophic cascade and how exactly do wolves change rivers? George Monbiot explains.
TRANSCRIPT: One of the most exciting scientific findings of the past half-century has been the discovery of widespread trophic cascades. A trophic cascade is an ecological process that starts at the top of the food chain and tumbles all the way down to the bottom. And the classic example is what happened in the Yellowstone National Park in the United States when wolves were reintroduced in 1995. Now, we – we all know that wolves kill various species of animals, but perhaps we’re slightly less aware that they give life to many others. Before the wolves turned up – they’d been absent for 70 years – the numbers of deer (because there had been nothing to hunt them) had built up and built up in the Yellowstone Park and despite efforts by humans to control them they’d managed to reduce much the vegetation there to almost nothing. They had just grazed it away. But as soon as the wolves arrived, even though they were few in number they started to have the most remarkable effects. First, of course, they killed some of the deer but that wasn’t the major thing. Much more significantly, they radically changed the behavior of the deer. The deer started avoiding certain parts of the park – the places where they could be trapped most easily – particularly the valleys and the gorges and immediately those places started to regenerate. In some areas, the height of the trees quintupled in just six years. Bare valley sides quickly became forests of aspen and willow and cottonwood. And as soon as that happened, the birds started moving in. The number of songbirds and migratory birds started to increase greatly. The number of beavers started to increase because beavers like to eat the trees. And beavers, like wolves, are ecosystem engineers. They create niches for other species. And the dams they built in the rivers provided habitats for otters and muskrats and ducks and fish and reptiles and amphibians. The wolves killed coyotes and as a result of that, the number of rabbits and mice began to rise which meant more hawks more weasels more foxes more badgers. Ravens and bald eagles came down to feed on the carrion that the wolves had left. Bears fed on it, too. And their population began to rise as well partly also because there were more berries growing on the regenerating shrubs. And the bears reinforced the impact of the wolves by killing some of the calves of the deer. But here’s where it gets really interesting. The wolves changed the behavior of the rivers. They began to meander less. There was less erosion. The channels narrowed. More pools formed. More riffle sections. All of which were great for wildlife habitats. The rivers changed in response to the wolves. And the reason was that the regenerating forests stabilized the banks so that they collapsed less often. So the rivers became more fixed in their course. Similarly, by driving the deer out of some places, and the vegetation recovering on the valley side, there was less soil erosion because the vegetation stabilized that as well. So the wolves, small in number, transformed not just the ecosystem of the Yellowstone National Park – This huge area of land… but also, its physical geography.
How Whales Change Climate
TRANSCRIPT: One of the most exciting scientific findings of the past half-century has been the discovery of widespread trophic cascades. Atrophic cascade is an ecological process that starts at the top of the food chain and tumbles all the way down to the bottom. We all know that whales eat fish and krill and some people have argued that killing whales is good for human beings as it boosts the food available for us to eat – and so you would think. But as the great whales declined so did the numbers of fish and krill. It seems counterintuitive – surely their numbers would rise as their major predators disappeared – but it now turns out that whales not only eat these animals they also keep them alive. In fact, they help to sustain the entire living system of the ocean. Whales feed a depth in waters that are often pitch dark and then they return to the surface to the photic zone where there’s enough light for photosynthesis to happen. There they release what biologists call fecal plumes – vast outpourings of poo – poonamis. These plumes are rich in iron and nitrogen – nutrients that are often very scarce in the surface waters and these nutrients fertilize plant plankton that lives in the only place where plants can survive – the photic zone. Fertilizing the surface waters isn’t the only thing the whales do. By plunging up and down through the water column, they also keep kicking the plankton back up into the photic zone giving it more time to reproduce before it sinks into the abyss. Even today, the whale populations have been greatly reduced, the vertical mixing of water caused by movements of animals up and down through the column of the oceans is astonishingly roughly the same as the amount of mixing caused by all the world’s wind and waves and tides. More plant plankton means more animal plankton on which larger creatures then feed. In other words, more whales mean more fish and krill. But the story doesn’t end here because plant plankton not only feeds the animals of the sea, it also absorbs carbon dioxide from the atmosphere. When eventually it sinks to the ocean floor, it takes this carbon out of circulation down to a place where it remains for thousands of years. The more whales there are, the more plankton there is. The more plankton there is the more carbon is drawn out of the air. When whales were at their historic populations, before great numbers of them were killed, it seems that they might have been responsible for removing tens of millions of tons of carbon from the atmosphere every year. Whales change the climate. The return of the great whales if they’re allowed to recover could be seen as a benign form of geoengineering. It could undo some of the damage we’ve done both to the living systems of the sea and to the atmosphere.