John Bishop was late getting to Mount St. Helens.
He was only 16 years old when it blew in 1980, and it would be another decade before he began crawling around the mountain as part of his doctoral studies.
“I was worried I missed all the action—‘Ten years, it’s all been studied,’” he recalls.
It turns out the dust, pumice, and other ejecta were only beginning to settle, and the mountain would continue to rumble, spit, and recover. In 1994, he found himself running from a mudflow, then watched as it moved fridge-sized boulders and shook the earth beneath his feet. Arriving at WSU Vancouver in 1998, he could make work on the mountain a weekly commute, a rare convenience for those eager to study the earth’s volcanic hotspots. In 2006, after a period of activity in which the mountain was closed to the public, he was one of the first to climb to the summit and watch whalebacks of solidified magma ooze out and break off 2,000 feet below.
(Photo Bill Wagner)
More important, Bishop, now an associate professor in WSU Vancouver’s School of Biological Sciences, bore witness as various life forms struggled to get a toehold among the rocks left virtually sterile by the blast 30 years ago. He’s seeing a biological Wild West where certain characters arrive on the scene and wreak havoc in the absence of established community forces or the usual ecological rules. The process is so tumultuous that Bishop and his colleagues are starting to rethink the process of succession in a heavily impacted biological system.
“It gets to how science occurs,” he says one crystal-blue summer day, with grasshoppers sounding like golf course sprinklers and the sun beating down on the white-gray rock of the Pumice Plain. “You work here for a decade or two and then you step back and say, ‘Wait, this is actually telling me something about the entire process of going from nothing, no biological organisms, to a forest that stood here before and will someday stand here again.’ We’re getting at really fundamental processes that determine how that happens.”
Biologists divide the blast zone around the mountain into various zones of disturbance. The outer edges were layered in ash and pumice. Areas closer in had singed but standing dead trees. Even closer to the volcano, forests were flattened.
“One-hundred-foot matchsticks,” says Bishop.
The Pumice Plain was Ground Zero for the blast’s debris avalanche and 800-degree pyroclastic flow. That life has returned at all is somewhat miraculous, but it’s also had a tough go of it.
The central player on the plain has been the lupine, a robust purple flower that in effect brings its own lunch by synthesizing nitrogen in the barren volcanic soil. Along with a few grasses, it’s the most obvious vegetation as we start walking on to the plain after a hair-raising drive from Windy Ridge on the mountain’s eastern flank.
“It’s a very two-dimensional plant community,” says Bishop, which is to say the plants are so low they offer little shade or protection for other plants and animals. “But you also see at the same time we have willows colonizing here. It’s easy to overlook them, but actually there are a lot of them. They’re everywhere, but at low density, and they’re quite small. And you have conifers colonizing. You have the beginnings of your next coniferous forest.”
In the two-dimensional world, the main animals are deer mice, killdeer, and horned lark. But the 3D world has voles, shrews, porcupine and weasels, yellow warbler and orange-crowned warbler, willow flycatchers, and sparrows. Elk come through pretty regularly.
“The willow,” says Bishop, “changes everything.”
Still, it’s a largely unsettled place. It lacks the diversity that can give an ecosystem both resilience—the ability to spring back from a disturbance—and stability—the ability to resist change in the face of a disturbance. As a result, the community is easily devastated by two insects—the willow stem-boring weevil and the poplar clear-winged moth.
Bishop points to a small willow with dead branches and a tell-tale dusting of what looks like sawdust. It’s frass—larvae dung—and evidence of the willow getting hammered. In an established ecosystem, the larvae might have predators to keep them in check. Not here. As Bishop and his students walk transects across the plain and document birds, mammals, and vegetation along the way, they’ve noticed that 85 percent of the willow stems over a certain size are being attacked.
“This plant is not that young,” says Bishop pointing to a battered willow. “It’s been here a while but its stems keep getting killed. It could easily be ten years old.”
Further down are willows that researchers sprayed to keep insects off. They sport tags—blue for male willows and pink for females—but they’re instantly recognizable without them.
“They’re the big ones,” says Bishop. Without the outsized impact of the insects, these willows flourished.
In the past, ecologists haven’t given much thought to the roles of insects in succession. Now Bishop is wondering if succession itself might be rethought to give greater weight to such high-impact species.
“What it’s made us realize more generally is that, as the species here sort out into a more stable community, you probably have a very unusual distribution of interactions among those species, where you have a lot of fairly extreme impacts of one species on another, more extreme than we see in more developed systems.”
He’s noticed something else as well. There are a lot of lupine and a lot of insects, in fact, millions of lupine and tens of thousands of herbivores that only eat lupine. Some are being described by scientists for the first time. Elsewhere on the mountain and surrounding Mount St. Helens National Monument are species like the western toad, which has its largest populations here. There’s the tailed frog, and large, diverse communities of huckleberry, mountain ash, salmonberry, often with animal-dispersed fruits. Bishop is seeing birds and mixed communities here that one doesn’t see elsewhere.
“I think that leads to a need to rethink the value of a place like this,” Bishop says, “that it may actually be extremely important for the long-term health of those species, that they can find a disturbed place and become very common.”
His thoughts on this are still forming, but they echo recent observations by WSU ecologist Mark Swanson and others in the journal Frontiers in Ecology and the Environment. It’s the kind of thinking that might alter how we, say, go into a burned forest and start replanting it, or how we take a clearcut and try to rush it back to an old-growth condition.
Indeed, if you want to make a case for natural disturbance, you might do well to start with this: Bishop, Swanson, and the platoon of researchers working here over the past few decades are coming to think that battered, burned, and blown-down Mount St. Helens now has the greatest biological diversity in the Cascades’ vast, forested terrain.
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Gallery: Mount St. Helens—a new land (Photographs by Bill Wagner)