Saturday, September 8, 2012

Lords of Nature

Lords of Nature is a great documentary I got to watch for a grad school class once.I really thought it was worth sharing, but it apparently isn't free, so all I can do is tell you about it.

Now, many of you may be aware of the idea that predators regulate the food chain. For example, if for some reason the rabbit population booms, rabbits become easy to catch, so the fox population booms, too, with a slight delay. The boom in foxes causes the rabbits to decline and crash, which means rabbits are harder to catch, so the foxes decline in turn. This is pretty well established ecological theory nowadays.

The Basics.
Another well-established facet of ecology, only slightly more advanced, is the Keystone Species idea. Keystone species are those that have a super strong influence not just on a single species, but on whole systems they occupy. Like an arch, if you remove the keystone, everything crumbles. This theory was born from the work of Robert Paine in 1966. What Paine did was remove sea stars from small patches of tidal habitat that were full of life. In these areas, sea stars were the top predator of all the different limpets, bivalves, barnacles, and other critters there. When the sea stars were removed, the diversity of species in those patches plummeted. The presence of the predator opportunistically picking off prey allowed many species to flourish, and its removal allowed certain species to out-compete others and basically take over.

Lords of Nature is about that dynamic, with wolves as the main case study. See, for decades, wolves had been gone from Yellowstone Park. They were hunted down and run almost entirely out of the country under the theory that wolves are bad, so we don't need 'em. They're "bad for agriculture," "bad for ranching," and keep populations of big game hunting species like elk and bison down. So, like mountain lions elsewhere, wolves got hunted down and killed en masse, with government bounties for carcasses. In the 1870's the wolf population of Yellowstone was around 300-400 wolves. In 1924, it became zero, and it stayed that way for decades.

In those decades, Yellowstone stopped . . . working. The elk population exploded, naturally, but the consequence of that was that they were eating, eating, eating. Riparian vegetation, usually not overgrazed because deer are cautious when going out into the open, pretty much vanished. This has major consequences for how rivers work, how banks are stabilized, how other species can use the river, and everything in the riparian systems began to degrade. Young trees got overgrazed, too, and couldn't grow to adulthood, so the famous Yellowstone forests just aged, and mature trees died without propagating.

Biologists were concerned about this and unable to understand why the forest was aging and why the riparian systems were degrading, until a couple of them, Bob Beschta and Bill Ripple of OSU (Go BEAVERS!) did a little thinking and figured out the connection: Yellowstone ecology started going sideways when the wolves were extirpated. They got in one of the coolest academic article titles I've ever seen. Wolves and the Ecology of Fear: Can Predation Risk Structure Ecosystems? Their 2004 paper suggests the answer to that question is yes. Wolves got reintroduced in 1995, and since then everything has begun to recover in very cool ways. There's a good writeup on the whole case study and relevant concepts here, for those who are curious.

Anyway, the reason all this with the documentary and the paper from 6 months ago and the comes to mind is a recent news article in the Oregonian. Apparently, the Eagle Cap Wilderness around the Minam River in eastern Oregon is now home to a new pack of wolves, and the latest count is that 23 pups were born in Oregon this year alone! I'm pleased to say I have a small amount of familiarity with that part of Oregon. The work I did monitoring salmon habitat earlier this year was in the adjacent watershed. Though I never visited the Minam specifically, I was all up and down the Upper Grande Ronde and Little Catherine Creek, just a hop, a skip, and a jump from this new wolf pack, and from what I've heard of that watershed, it's one of the most pristine areas in the state.

I hope I've impressed on you why this is such good news. On levels we're just beginning to understand, wolves make forests and rivers . . . work.

1 comment:

  1. I didn't know any of this, actually. I mean, it makes sense, to a degree (at least the parts about over grazing ans the like) but I'd never really thought about it before. Go OSU for figuring it out and re-introducing the wolves.