Update 10/20: Crosscut has a version of this post.

What happened to the Olympic Peninsula after its wolves were hunted to extinction in the 1920s? There’s a fascinating new study (pdf) out on this question—the first of its kind as far as I know. As it turns out, eliminating this one keystone species sent shockwaves through the whole ecosystem. Some of the effects were felt almost immediately after wolves were extirpated and some are only just now becoming clear.

It’s a shame that reading articles like means hacking through verbiage that can feel as dense as an Olympic rainforest—it’s all “flow-induced shear stresses,” “fluvial erosion,” and “ungulate exclusion”—because the study’s content is incredibly important for lay people to understand. (Good ordinary language articles are here and here.) The upshot is that researchers have determined that the Olympic wolves were river-keepers, in an indirect but very real sense.

Here’s how it worked. Once upon a time, healthy wolf populations kept the native elk herds lean. But when the wolves were killed off, the elk populations spiked (with a colossal and much-noticed-at-the-time boom in the 1930s). The booming elk herds spent much of their time in the lush river bottoms, cropping the living heck out of new tree growth and hammering the seedlings of cottonwood, bigleaf maple, and even some conifers. Those young trees had stabilized the banks along the region’s fast-flowing rivers. And without new saplings and their fortifying root-systems, the rivers began to erode their banks, eventually channelizing and “braiding” as they spread out along the newly-unstable valley floors.

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    • By comparing places where Olympic rivers are relatively free of elk (owing to hunting or other causes), the researchers were able to document substantial differences in the shapes and dynamics of the rivers. In fact, the researchers even hypothesize that the native salmon populations in Olympic National Park have been harmed by a river system that is less supportive of certain invertebrates.

    If you’ve hiked along the wilderness Olympic rivers, particularly on the rainforest side, you’ve no doubt marveled at the clean meadow-like glades where old alders and bigleaf maples reach for sky amid grassy meadows. There are few young or intermediate-age trees. They’re lovely places but also symptoms, perhaps, of something missing from the wilderness. Maybe you’ve even seen the big Roosevelt elk there, cropping away at the green growth. You’ve certainly never seen wolves there as travelers in the Olympics once did.

    Luckily, there’s a solution at hand. We should restore wolves to the Olympic Peninsula just as we have successfully done in the Rocky Mountains. If wolves were returned to their home in the Olympic forests, we might expect that the next several decades would mean a gradual restoration. Young maples and cottonwoods might thrive again in river bottoms, knitting stronger river banks, and improving the health of the salmon nurseries. I’ll bet a dozen (or a hundred) other things would happen too — wolf-connected effects that we’re not even aware of now.

    The good news is that wolves are already returning to the state. But while gray wolves have begun a natural reintroduction of eastern Washington and eastern Oregon, it is unlikely that they will bridge the relatively developed areas west of the Cascade Mountains to reach the Peninsula. In any case, the Olympic wolves were probably slightly different from their interior cousins: they were likely a coastal subspecies of gray wolf, very similar or identical to the wolves that still range in British Columbia’s coastal regions. These northern coastal wolves, by the way, would make an ideal transplant population.

    This study (pdf) of Olympic National Park comes from Oregon State University — the same folks who brought to light the fascinating ripple-effect of ecosystem restoration that occurred when wolves were reintroduced in Yellowstone National Park.