Wildflower is published quarterly by the Wildflower Center. Its content is national in scope with articles about the conservation and use of native plants as well as news from the Wildflower Center. A subscription is provided to Wildflower Center members as a benefit of membership.
The verdant scene viewed from atop Coldwater Ridge this summer made it hard to believe that just 25 years have passed since the eruption of Mt. St. Helens turned lush woodland into a barren moonscape. Today, a multi-colored wildflower carpet competes for space with abundant willow, alder, and western hemlock trees. In the distance, the volcano - with its gaping crater and smoldering lava dome - sends up occasional puffs of white steam against a turquoise sky. The teeming landscape hardly seems like it could be the same place described in accounts following the 1980 eruption as dark, desolate, and lifeless.
But indeed it is. Twenty-five years earlier, at 8:32 a.m. on the morning of May 18, 1980, the volcano exploded with the fury of 500 atomic bombs, launching ash 60,000 feet skyward while spewing pumice, rocks, and super-heated gases across 230 square miles of pristine Pacific Northwest forest. The unexpected lateral blast that day turned the whole north side of the mountain into the largest landslide in recorded history, burying nearby lands in hundreds of vertical feet of volcanic debris and, further afield in the so-called "blast zone," knocking down millions of trees like so many toothpicks in the wind. Even though they knew the blast was big, when the dust settled scientists were still amazed by the sheer amount of destruction wrought by the eruption, which had literally sterilized thousands of acres of land left in its wake. Realizing they had a unique opportunity to watch the region restore itself from scratch, scientists urged the government to set aside the affected lands as off-limits to resource extraction and development. Congress obliged, creating the 110,000-acre Mt. St. Helens National Volcanic Monument in 1982 in order to facilitate research and education on the nature of volcanic eruptions and their effects on the surrounding landscape - in the absence of human attempts at reforestation.
Nature Healing Itself
In the subsequent quarter-century of monitoring and analysis at Mt. St. Helens, researchers already have gleaned secrets heretofore unknown to science not only regarding volcanic eruptions, but about the way nature handles ecosystem restoration when left to its own devices. In fact, what nature did without human intervention aimed at helping in its restoration offers an important lesson for ecologists looking to control invasive species.
While each individual discovery has proven significant in its own right, the biggest surprise overall has been the rapid rate of recovery on the lands surrounding the volcano. Within two years of the eruption, for instance, researchers were amazed to see pretty little purple flowers sprouting up on the decimated pumice plain directly beneath the volcano's exposed crater. Scientists speculate that these hardy prairie lupine (Lupinus lepidus) plants, native to the Pacific Northwest, came from seed of a plant that after surviving the eruption was likely washed downhill or transported by wind. Regardless of how they got there, though, the lupines were playing an important ecological role by improving soil quality for subsequent colonizing life forms.
Lupine has an association with a bacteria that takes nitrogen from the air and converts it into a form that other plants and animals can use," says Virginia Dale, a plant ecologist with the Oak Ridge National Laboratory who has devoted a significant portion of her career to researching ecosystem responses to the Mt. St. Helens eruption. "Since the volcanic material on the ground following the eruption had very low nutrient composition, the nitrogen provided by the lupines gave a tremendous pulse to the conditions so that when other plants came in, they had this critical element available to them.
Indeed, within just a few more years it became apparent how well the lupines - both the prairie variety as well as the stouter broadleaf lupine (Lupinus latifolius) had done their job. By the mid-1980s, color was running up and down the recently devastated ridges surrounding Mt. St. Helens during summer flowering seasons. Fireweed (Chamerion angustifolium), common red paintbrush (Castilleja miniata), Cardwell's penstemon (Penstemon cardwellii) and other wildflowers - many of them more typical in higher-elevation alpine meadows on the flanks of neighboring cascade peaks like Mt. Rainier and Mt. Adams - dazzled researchers and day trippers alike.
For vigorous colonizing early successional species, Mt. St. Helens was quite an opportunity," says forest ecologist Peter Frenzen, who came to work for the U.S. Forest Service at Mt. St. Helens soon after the 1980 eruption. Today, Frenzen serves as monument scientist, which means he is responsible for coordinating on-going research, transferring scientific findings to visitor information programs, and monitoring the recovery of plant and animal life at Mt. St. Helens.
Frenzen defines the concept of ecological succession as the pattern of one community of plants and animals gradually replacing another in response to changing environmental conditions in a given region. Many wildflowers are considered "early successional" species by ecologists, meaning that they colonize disturbed or otherwise open lands, where they can get a lot of sunlight to produce many seeds while serving as an excellent food source for flying and crawling insects and other discriminating creatures. In contrast, old-growth Douglas fir trees - tens of thousands of which were blown down by hot gases during the 1980 eruption - fill in on terrain late in the successional cycle, and can live on as the dominant species in Pacific Northwest forests for thousands of years if they are not killed off by natural disasters.
The forest had been stripped off, and there were varying degrees of organics in the deposits," elaborates Frenzen. "So these [wildflowers] responded to a flush of available nutrients and also, most importantly, available sunlight.