Biological Research

Posted On: Filed Under: Biological Research

The effects of the eruptions of Mount St. Helens on glaciers, glacier caves, caves and mudflows, etc.

The objectives of this project are to study effects of eruptions on glaciers and glacier pseudokarst and to map glacier caves and glacier margin and other caves on Mount St. Helens. In meeting these objectives we will document and photograph (1) these features; (2) effects of ashfall and mudflows on newly exposed glacier bed and downslope detritus and erosion produced by melting glaciers; (3) effects on crater, dome and caves in crater.

 

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Posted On: Filed Under: Biological Research

Population ecology of the aphid Aphthargelia symphoricarpi on Mount St. Helens

I have examined the ecology of the aphid Aphthargelia symphoricarpi in terms of its interactions with its host plant Polygonum newberryi and its major predator, the ant Formica fusca. My approach involves a combination of field experimentation and observation with mathematical modelling.

 

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Posted On: Filed Under: Biological Research

Effects of pocket gopher (Thomomys talpoides) mounds on plant reestablishment processes.

This studydocuments that pocket gophers in the blast zone did survive the May 1980 eruption of Mount St. Helens, and they did have an effect on early plant re-establishment within the blast zone. One study site is approximately 20 km northeast of the volcano. This site received a layer of pumice and ash to an average depth of 12 cm in 1980. Vegetation on gopher mounds was compared to that on surrounding un-mounded soil surface. Findings show that species composition is different; there are more residual species on mounds, and seedlings on mounds are more likely to survive and contribute to future local population growth.

 

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Posted On: Filed Under: Biological Research

Ecology of the tadpoles of the tailed frog (Ascaphus truei)

Data on the microhabitat parameters, especially pertaining to flow rate and substrate characteristics, of the stream-inhabiting tadpoles of the tailed frog (Ascaphus truei) were collected at two tributaries of Clearwater Creek at Mount St. Helens, Washington and at Parker Creek on Mary’s Peak, Benton County, Oregon. This is the only tadpole in North America that is highly specialized for maintaining position and feeding from algae while attached to rocks via an enlarged oral disc with many rows of labial teeth. Positions of tadpoles in the streams were correlated with oral morphology and associated anatomy. Because of the length of the larval period of Ascaphus, there are usually 2 to 3 yearly cohorts in the streams at one time. We hypothesized that the interaction of the abilities of the tadpoles to adhere to rocky substrates and the size of the tadpole would result in microhabitat segregation. Whether small or large tadpoles occupied fast versus slow water would depend on the growth pattern of the tadpole (drag) versus the changes of the adhesive abilities with size.

 

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Recovery of mycorrhizal associations on Mount St. Helens.

This work has studied the recovery of mycorrhizal associations on Mount St. Helens since the eruption in 1980. Mycorrhizal associations are symbioses between plants and fungi localized on the roots of plants. The fungi provide much of the nutrients utilized by the plants and the plants provide carbohydrates to the fungi. The associations on Mount St. Helens range from those plants that form facultative mycorrhizal associations, many herbaceous species including Lupinus lepidus, L., latifolius, and Epilobium angustifolium, to the coniferous trees that are obligately dependent on mycorrhizae.

 

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Posted On: Filed Under: Biological Research

Ecosystem recovery on the debris avalanche

The object of this study is to monitor ecosystem recovery on the debris avalanche created by the May 1980 eruption of Mount St. Helens. Vegetation was significantly reduced in the blast area. Plant survival and diversity was apparently related to growth form. Plants with underground dormant buds survived best. Plant recovery has been correlated with moisture rather than physical structure of the substrate.

 

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Disturbance and recovery of soil, microbial, and plant processes.

Our work has focused on disturbance and recovery of soil, microbial, and plant processes following volcanic disturbance. Particular emphasis was placed on spatial relationships involving the carbon and nitrogen cycles. Comparative studies have been conducted at six sites that were disturbed to varying degrees by the May 1980 eruption of Mount St. Helens. These sites include Butte Camp, Upper Pine Creek, the Lahar on the Muddy River, the former Timberline parking Area, and Meta Lake.

 

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Mortality and revegetation of an old-growth forest buried by the Muddy River mudflow

Natural revegetation was studied in an old growth terrace forest buried by 25 to 150 cm of sand to boulder sized material from the Muddy River mudflow. Objectives were: 1) examine patterns of mortality, growth and revegetation along a gradient of mudflow deposition; 2) provide baseline data for future estimates of fragmentation and decay of mudflow killed trees and assess the influence of the dead trees on revegetation processes; 3) establish a 2.5 hectare grid of stem mapped forest to track ecosystem recovery and describe important processes through time.

 

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Natural revegetation of debris avalanche and lahar (mudflow) deposits

Natural revegetation was studied on debris avalanche and mudflow deposits primarily northwest and southeast of Mount St. Helens on Forest Service land. Objectives were: 1) examine patterns of revegetation in response to large and small scale surface changes as deposits are modified by geomorphic processes; 2) characterize revegetation on different types of sites in the devastated area (North Fork Toutle River debris avalanche and Muddy River mudflow) and 3) establish a system of documented permanent plots to track ecosystem recovery and describe important processes through time.

 

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Natural revegetation of upland portions of the blast zone

Natural revegetation was studied within the northeast sector of the blast zone on Forest Service land. Objectives were: 1) compare revegetation on major disturbance types (pyroclastic flow, debris avalanche, blown down and standing dead forest); 2) examine the effects of pre-eruption plant communities and the presence/absence of snowpack on current vegetation; 3) establish a system of permanent plots to track ecosystem recovery and describe important processes through time.

 

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