Nature Notes

Vol. II June-July 1984 No. 4


A crowd gathered at Longmire at 5:30 A.M. on Wednesday, July 25 through gracious invitations from the Forest Service, and strategic organization and generous efforts by the staff left behind, a crew of Mount Rainier interpreters headed for Mt. St. Helens and a unique tour through the infamous Red Zone. After signing our lives away and loading up on cinnamon rolls and coffee, we arrived at Windy Ridge where we joined the staff from Mt. St. Helens National Volcanic Monument. We travelled into the restricted zone and were treated to two informative presentations.

One presentation was an introduction to the geology of the area. Tim Delano, Volcanic Monument staff interpreter, described the events leading up to the major blast. We listened intently while sitting next to a 15 foot high crumbling bank of volcanic debris. Tim explained the harmonic tremors of March 20 which helped raise the molten material and started building the bulge. While describing the May 18 blast, he pointed to the 1200 foot ridge over which the lahar or mud flow travelled. He also pointed out the line on the far side of Spirit Lake which the lake sloshed up to during the blast. He talked about the intense heat and gas as we watched steam rise from fumeroles and became stiffled by the odors of warm sulfur and iron compounds.

Probably the most powerful view of all was looking into the crater and seeing the new dome, which is forming at the rate of about 5 to 15 feet per day. Enough material to fill the Kingdome in Seattle is being added each month. The intensity of the eruption of Mt. St. Helens was brought into focus by these views in the restricted zone.

Equally as exciting and even more perplexing was the information provided by Jim McMann on the ecology of the area since the blast. Jim and others have been studying the area, quantifying data, and hypothesizing on every aspect of its recovery. One of the most interesting questions they are trying to answer is which plants and animals now in the area are residual having survived the devastation, and which are migrants and, even more importantly, why.

Very little wildlife was apparent as late as 1982. There were probably many plants, especially those with bulbs and corns which survived the eruption. But it wasn't until some geomorphic activity occurred that these same plants could be reactivated and reach the surface. The concrete-like, water repellent surface of the ash had to be blown or washed away or broken up by a force, foot prints, animal tracks and even helicopters. Some examples of vegetation we observed in the area were lupine, fireweed, ocean spray and sedges. Jim also has observed that every conifer species in the area except Douglas fir has sent out root sprouts since the blast.

The trees in the area that were not burned but covered in ash were expected to die due to an increase in temperature (of about 50°C) caused by solar radiation intensified by the ash. Unexpectedly, in the year following the eruption (1981), biologists observed that the trees did not die, but actually had 2-1/2 times the maximum growth ring width for the last 500 years'. The timing of the blast may actually have worked in favor of the trees. The old needles were destroyed, but the new growth was in bud at the time of the blast and was protected. When the buds opened, the new needles gleaned all the energy (new needles being more efficient producers than older needles) and there was maximum development -- exactly the opposite of what was expected.

Biologists are discovering many interesting relationships between insects and plants. Insect matter is adding more organic material to the newly forming soil than the plants. About 20 grams of dry insect organics are added per square mile per year. In addition, insects are increasing the spread of mycorrhizae, the root fungi which aid in fixing nitrogen and increase the plant's efficiency of water and phosphorus intake. Grasshoppers are especially adept at this as they concentrate the mycorrhiza which they eat, holding their feces until they eat again and drop the feces on a new plant. Because the environment was sterile after the eruption these kinds of relationships are more easily observed.

Jim seemed especially interested in some of the mammal species and their tenacity in the face of the devastation. He has found that some rodents are actually residual, somehow surviving the blast in an epicenter. Creeping voles, deer mice and pocket gophers have all persisted. Jim mentioned one of his earlier discoveries while they were observing the area by helicopter. He noticed some small green patches tucked here and there amidst the barren landscape. Upon closer examination it was discovered that each green spot had at least one active pocket gopher in it. The rilling activity of the gopher was actually speeding up the successional processes in the tephra. This contrasts with subalpine meadows where the rilling helps slow down the succession of the meadows by keeping them in an open state.

Unlike the terrestrial flora and fauna, the aquatic animals did not benefit from subsequent geomorphic activity. Immediately following the blast the organisms in the streams floated above the sinking volcanic material and most of the invertebrates, reptiles and amphibians survived. But by 1981, there were no vertebrates and very few invertebrates. The moving water, with all its debris, proved to be a very abrasive, scouring force that the organisms could not survive.

Aside from all the information being collected by first hand observation of the area, Jim and other biologists are also testing many ecological theories. They are taking full advantage of the unique sterile conditions that the Red Zone provides to study theories that under normal conditions could not be studied so exactly. Theories such as natural selection, island biogeography theory, and how the form of the vegetation or "architecture" of a community determines the inhabitants are examples. They are asking some fascinating questions and collecting an incredible amount of information of interest to scientists and curious naturalists alike.

Once left to our own devices, the interpreters of Mount Rainier lost no time in living up to their "fern feeler" reputation. Replacing ferns with fumeroles and mud, we wandered around the shore of Spirit Lake. More than one person found themselves "totally immersed" in the thick ooze of the area. Aside from the hazards of the muk, and quicksand, the place was a teeming bed of curiosities. Steam vents, brilliant hot water algae, large and lightweight pumice boulders, and tortured timber were everywhere. The trip was a rare and enlightening opportunity to probe into the most amazing geological and ecological event of our time. And the knowledge gained is valuable background from which to interpret volcanic processes to visitors at Mount Rainier.

Barbara Blackie

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