40 years ago, Mount St. Helens blew its top. Here's how it got green again

Forty years ago this month, Mount St. Helens in Washington state erupted in spectacular fashion. On May 18, 1980, a violent volcanic explosion ripped the top 400 metres off of the nearly 3,000-metre-high mountain, leaving an enormous horseshoe shaped crater.  

Pulverized rock and ash were launched many kilometres into the sky, as an enormous plume formed.  

Superheated 300-degree winds full of toxic gas and hot rock dust cascaded down the mountains at 200 km/h, wreaking enormous havoc. Six hundred square kilometres of forest was obliterated. Homes and highways were destroyed and buried. Ash rained on much of the Pacific Northwest, and 57 people died. 

Charlie Crisafulli was a young undergraduate student who went there not long after the eruption as part of a summer research project looking at the impact of the volcano on ecosystems. 

Today he is a research scientist with the U.S. Forest Service at the Mount St. Helens National Volcanic Monument. That single summer evolved into a four-decade-long career, during which he witnessed the sometimes surprising ways ecosystems around Mount St. Helens came back to life.

Crisafulli joined Quirks & Quarks host Bob McDonald to talk about the Mount St. Helens eruption 40 years later.

This interview has been edited and condensed.

When you first got to Mount St. Helens after the eruption, what was it like?

Well it was quite astonishing. As far as the eye could see, the forest that had been there had been levelled or absolutely obliterated and no longer present whatsoever. And it was a steaming landscape with fetid waters and just eerie to say the least. And it appeared that there's no way any life could have possibly survived.

What kind of surprises did you have about what actually did survive the blast?

The big "aha" moment was that there was an archipelago, a series of islands with survivorship and in some cases they were tiny islands. Perhaps a single individual plant or a sapling of a tree. In other cases, lakes that had been afforded the protection of ice and snow because of the timing of the eruption. In this case, entire aquatic ecosystems survived in situ. 

What about animals? 

Again, timing turned out to be really important. Perhaps a dozen or more of the small mammals that were denizens of the Mount St. Helens pre-eruption landscape had already sought retreats of their daytime residences, under the ground or in logs. So they were spared the brunt of the erupting forces, whereas diurnal animals such as squirrels and chipmunks were in harm's way. 

All of the five large mammals — mountain goats, elk, deer, black bear, mountain lions — all instantly perished within 10 minutes of the onset of the eruption.

Do you remember the first time you saw a green plant poking through that devastated landscape?

Oh I sure do, and these are indelible memories because just imagine being a young ecologist half trained, being dropped off in a chopper into this place that was so foreign. There was nothing. It was monochromatic. Everything was grey, kind of white to blackish in colour. I absolutely recall one of my first trips into the blast area and I looked over and I thought I saw a little glimmer of green and sure enough it was this parsley fern, just a tiny fern growing up through the mantle of ash.

I was in there just yesterday out on the Pumice Plain and revisited that same individual plant. And so every year for 40 years now I go and greet that plant as I enter the blast area.

How is it possible for a plant to actually get nutrients out of what's basically just pulverized rock?

What's really noteworthy is that there's always heroes in these landscapes.

And what we learned early on, by 1983, is that a very unlikely plant species played an enormous role. And this was the tiny prairie lupine. This species survived high on the flanks of Mount St. Helens and somehow some seeds got down right in front of the crater within the first year after the eruption. And that moment was the beginning of what would become this vast spread of lupines across this 15-square-kilometre area. That was the location that initiated so much ecological change. And the reason that lupine was able to exploit this barren landscape, that was absent of nitrogen and carbon, was because of a special association it has on its roots with the bacteria.

This bacteria can produce nitrogen in the soil and it provides that nitrogen to the plant and in turn the plant fixes carbon through the process of photosynthesis. So it's this beautiful relationship — if you scratch my back I'll scratch yours. As a result, lupines could exploit the landscape and, in doing so, they increased the nitrogen and the carbon and the amount of organic material and facilitated the colonization of all these other plants and animals that were arriving. So lupines played this incredibly important role in many locations around the volcano where life was obliterated.

What other, as you say, biological heroes — both plants and animals — were around in the early part of the recovery at Mount St. Helens?

The pocket gopher was incredibly important. This is a small rodent and they live beneath the ground. As they're digging, they have more soil than they know what to do with. So they expel it to the ground surface in the form of a mound. When you're flying a couple hundred metres above the ground in a helicopter, you can see these dark brown mounds of the old forest soil that they had expelled to the surface.

These are nature's little rototillers. By churning the old, nutrient-rich soil complete with the biota of the soil microbes, fungal spores. So what we learned pretty quickly is these mounds increase the suitability of the site chemically, physically and biologically, and thereby promote plant growth. 

So when you visit Mount St. Helens now, how different does it look to you compared to when you first saw it right after the eruption?

It has transformed from a largely grey landscape to a largely green landscape.

It's really astonishing to look at this landscape and recognize just how vastly it's different from the surrounding areas. And when I say that, I mean the region going from northern California up to southern British Columbia, and it sticks out from space still 40 years later. If you pull up a satellite image it's like, "Wow, what's this big area that looks so different than everything else?" Well, it's the Mount St. Helens landscape.

The second great epiphany is that if you leave nature alone and don't tamper, don't try to fix it, don't try to restore it, leave it alone, these really remarkable, slowly regenerating, complex, early habitats develop well.

You've been at this now for 40 years. What's it been like for you to follow a project like this for so long?

Personally, a great deal of my identity is tied up in this place because it's not like I just go there to work. From my house, I see Mount St. Helens. It's the place I've taken my two daughters to pick huckleberries and to forage for fungi in the fall and to go fishing. It was the first place they ever fished and learned how to cross country ski and snowshoe.

Mount St. Helens is really intertwined in my very fibre, both from a personal and career perspective. I arrived at age 22, I thought it was gonna be a summer college position, but it turned into 40 years. It's quite remarkable to be able to spend so much time on that landscape and get to learn the cast of characters and see an event that's happened thousands of times over many thousands of years throughout Cascadia, and to actually be there to witness how these forests in their most initial stages begin the foundational work of creating what one day will be an old growth forest.

Written and produced by Mark Crawley