FT 4 - SOLD OUT - Mount St. Helens Westside Field Trip

Trip Overview
The 1980 eruption of Mount St. Helens was dramatic in terms of the variety of volcanic processes and the spatial extent of their effects on ecosystems. Complex geophysical forces created exceptional opportunities to study initial ecological responses and longer-term successional processes across lowland to subalpine forests, meadows, lakes, streams, and rivers and gave scientists opportunities to interpret geophysical and ecological processes. These conditions make Mount St. Helens a rich environment for learning about the ecology of volcanic areas and ecosystem response to many types of disturbance. Mount St. Helens is a unique living laboratory for addressing questions that require long-term observations and experiments that take advantage of its diverse conditions.

The tour will enter the Mount St. Helens National Volcanic Monument from the west side and drive into the devastation zone. As we drive in, field trip participants can see areas impacted by mudflows, the debris avalanche, the blast, and pyroclastic flows as well as ash deposits on top of all these disturbances. The tour will stop at Mount St. Helens Visitor Center in Castle Rock and the Forest Learning both of which are handicap accessible. We will have lunch at picnic tables near Coldwater Lake, which was created when the debris avalanche deposit dammed Coldwater Creek.
The tour will also visit the Sediment Retention Structure (SRS) on the North Fork of the Toutle River that was established in 1989 by the U.S. Army Corps of Engineers to retain some of the sediment in the Toutle River flowing down from the slopes of Mount St. Helens. Because the SRS blocks upstream passage of salmon and steelhead, the Corps also constructed a Fish Collection Facility (FCF) just downstream from the SRS. Fish are collected at the FCF and transported via tank truck and released at one of two sites on tributaries upstream from the SRS. The Washington Department of Fish and Wildlife now operates and maintains the FCF and release locations.

The group will take two hikes, which are not easily accessed in wheelchairs. The Hummocks Trail is 2.4 miles and relatively flat. Along this trail, participants can observe vegetation reestablishment on the debris avalanche deposit. The new ponds created by the eruption now support rich diversity – including beaver. Massive erosion is observable, for the deposit averaged 45 m deep and buried the North Fork of the Toutle River, which has since been reestablished. Short-lived alder trees are abundant, but some are dying – so successional processes are quite active. The hike from the Coldwater Science and Learning Center (CSLC) to Coldwater Lake is about 1 mile through the blast area. We will have lunch at the picnic area near Coldwater Lake.

Harry’s Ridge Trail departs from Johnston Ridge Observatory and provides spectacular views into the crater and areas devastated by the pyroclastic flow and blast. On clear days along the trail, hikers have panoramic views of Spirit Lake, Coldwater Peak, Mount Adams, and the pumice plains, as well as Mount St. Helens. The full hike is 8 miles, but we will walk out as far as time allows - closer to 1-2 miles (or 2 to 4 miles round trip). Wildflowers established since the 1980 eruption will be blooming.

The drive to and from the first stop will be 1 to 2 hours (depending on which bus you are on).

In the aftermath of the eruption, a highly heterogeneous environment resulted from numerous factors. The eruption involved a complex set of geophysical forces, varying in their intensity and acting upon an array of different pre-eruption biological communities, successional stages, and site conditions distributed across complex montane topography. These factors led to a landscape mosaic of broadly defined disturbance zones that were characterized by the amount, type, and distribution of residuals (biological legacies—organisms and organic materials that remain after a disturbance) from the pre-eruption ecosystems. Collectively, these zones can be viewed as a gradient of disturbance severity ranging from complete annihilation of all life immediately in front of the crater in the pyroclastic-flow zone and on the debris avalanche deposit, to areas of high survivorship of most taxa 30 km to the north in the tephra-fall zone.

Nearly all plant and animal species inhabiting the landscape before the eruption had at least some individuals that survived by many mechanisms in small and isolated safe havens throughout some parts of the landscape and waterways. Subsequent ecological change resulted from growth and spread of surviving populations, joined by numerous colonists that immigrated from distant source populations. Community and ecosystem development was influenced by physical changes to the environment such as weathering of substrates, nutrient enrichment, and secondary disturbance. These processes both retarded and accelerated plant establishment and growth and, hence, animal-community assembly, depending on local circumstances. What has been learned from research on ecological responses at Mount St. Helens is influencing the understanding of succession, animal-community assembly, disturbance ecology, ecosystem management, evolution and the origin of life, trophic interactions, and landscape ecology.

Equipment and Attire
Participants should be prepared for a cool morning and hot afternoon with bright sun and little shade. Rain is unlikely but possible. Hiking shoes, sunscreen, a hat, light jacket, and mosquito repellent are recommended.

Field Trip Fee is $100 per person.